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Analytical and Bioanalytical Chemistry (v.396, #2)

The importance of asking, mentoring and building networks for academic career success - a personal and social science perspective by Julie A. Stenken; Anna M. Zajicek (pp. 541-546).

is a Professor of Chemistry and Biochemistry at the University of Arkansas and holds the 21st Century Chair in Proteomics. Prior to joining the University of Arkansas, she held her primary appointment in the Department of Chemical Biology and a joint appointment in Biomedical Engineering at Rensselaer Polytechnic Institute in Troy, NY (1996–2007). Her research interests include bioanalytical chemistry and in vivo chemical measurements focused towards applications in neuroscience and wound healing. Professor Stenken has mentored numerous undergraduate and graduate students on to very productive careers in the chemical sciences. is a Professor of Sociology at the University of Arkansas. She joined the University of Arkansas in 1994. In addition to holding an appointment in the Department of Sociology, she served as a Coordinator for the Gender Studies Program, Graduate Program Director, and a Faculty Research Associate in the Office of Institutional Diversity and Education. Her research interests include the intersectional nature of social inequalities and the integration of an intersectional perspective across different social science disciplines. Recently, she has been involved in interdisciplinary research focusing on successful strategies to institutionalize programs and policies aimed at the advancement of historically underrepresented groups in STEM disciplines.

The importance of asking, mentoring and building networks for academic career success - a personal and social science perspective by Julie A. Stenken; Anna M. Zajicek (pp. 541-546).

Damià Barceló, Peter-Diedrich Hansen (Eds.): Biosensors for the environmental monitoring of aquatic systems. Bioanalytical and chemical methods for endocrine disruptors by Boguslaw Buszewski (pp. 547-548).

James S. Fritz, Douglas T. Gjerde: Ion Chromatography, 4^th ed. by Paul Haddad (pp. 549-550).

Steven D. Brown, Romà Tauler, Beata Walczak (Eds.): Comprehensive chemometrics. Chemical and biochemical data analysis by Jürgen W. Einax (pp. 551-552).

Marine ecotoxicology by Christophe Minier; Philippe Garrigues (pp. 553-554).

is professor at the University of Le Havre and head of the Etiology of Environmental Stresses group within the Laboratory of Ecotoxicology (LEMA). He is the coordinator of research activities on endocrine disruption for the national consortium “EXECO” (a group of 6 French laboratories), and the leader of the European research program Risk Analysis Associated with Endocrine Disruption—RAED since 2002. Dr Minier’s research activities are in the area of endocrine disruption, environmental genotoxicity and studies on the multixenobiotic resistance (MXR) system. His particular focus is on the assessment of exposure (bioavailability and interactions with ABC transporters), and its effects at several levels of biological organization (from molecular components to the whole organism). The main organisms he studies are fish and mollusks living in both marine and freshwater environments. is a CNRS research director and is currently the head of the Institute of Molecular Sciences (ISM, UMR 5255 CNRS) at the University of Bordeaux. His research interests are the analytical aspects (chromatographies and spectroscopies) related to the detection of organic pollutants and their environmental fate and toxicological effects. He has been involved in the development of biochemical markers as early warning systems for the healh assessment of marine ecosystems through the coordination of large research projects (i.e., GICBEM, BIOMAR, BEEP) supported by the DG Research (European Commission, Brussels). Dr. Garrigues has authored about 180 publications. He was a member of the executive committee of SETAC Europe (97–99) and chairman of the division “Chemistry in the Environment” (DCE) of the European Association for Chemical and Molecular Sciences ( EuCheMS, 03–08). He has also organized various congresses, most of which have been related to international scientific societies (SETAC, ISPAC, EuCheMS).

Marine ecotoxicology by Christophe Minier; Philippe Garrigues (pp. 553-554).

Clam shell repair from the brown ring disease: a study of the organic matrix using Confocal Raman micro-spectrometry and WDS microprobe by Nowenn Trinkler; Maylis Labonne; Frédéric Marin; Aurélie Jolivet; Marcel Bohn; Céline Poulain; Jean-François Bardeau; Christine Paillard (pp. 555-567).

Since 1987, the Manila clam Ruditapes philippinarum has been regularly affected by the brown ring disease (BRD), an epizootic caused by the bacterium Vibrio tapetis. This disease is characterized by the development of a brown deposit on the inner face of valves. While most of the clams die from the BRD infection, some of them are able to recover by mineralizing a new repair shell layer, which covers the brown deposit by a process of encapsulation. The purpose of this work was to study the organic matrix of the shells of Manila clams in the inner shell layer before, during and after the brown deposit and during the shell repair process by confocal Raman micro-spectrometry and wavelength dispersive spectrometry (WDS) microprobe. In addition, the organic matrix of the repaired shell layer was extracted and quantified, by using standard biochemical shell matrix extractions protocols. The brown deposit exhibited high luminescence intensity in Raman spectra, and an increase of S, C, Sr (forming two peaks) and a decrease of Ca, Na concentrations (% w/w), using WDS microprobe mapping and cross-sectional transects. The signature of these trace elements was similar to that recorded on periostracal lamina (% w/w). The high S concentration likely corresponds to the presence of a high amount of sulfated organic compounds. Interestingly, on cross-sectional transects, before the brown deposit, a thin layer of the shell showed also a high luminescence, which may suggest that this layer is modified by bacteria. After the brown deposit, at the beginning of the shell repair process, the luminescence and the S concentration remain high, before declining the level found in non-BRD-affected shells. Quantification of the organic matrix shows that the shell repair layer zone is significantly different from non-BRD-affected shell layer, in particular with a much higher amount of insoluble matrix.

Keywords: Ruditapes philippinarum ; Brown ring disease; Organic matrix; Raman micro-spectrometry; WDS microprobe; Shell repair

Evaluation of an hPXR reporter gene assay for the detection of aquatic emerging pollutants: screening of chemicals and application to water samples by Nicolas Creusot; Saïd Kinani; Patrick Balaguer; Nathalie Tapie; Karyn LeMenach; Emmanuelle Maillot-Maréchal; Jean-Marc Porcher; Hélène Budzinski; Sélim Aït-Aïssa (pp. 569-583).

Many environmental endocrine-disrupting compounds act as ligands for nuclear receptors. Among these receptors, the human pregnane X receptor (hPXR) is well described as a xenobiotic sensor to various classes of chemicals, including pharmaceuticals, pesticides, and steroids. To assess the potential use of PXR as a sensor for aquatic emerging pollutants, we employed an in vitro reporter gene assay (HG5LN-hPXR cells) to screen a panel of environmental chemicals and to assess PXR-active chemicals in (waste) water samples. Of the 57 compounds tested, 37 were active in the bioassay and 10 were identified as new PXR agonists: triazin pesticides (promethryn, terbuthryn, terbutylazine), pharmaceuticals (fenofibrate, bezafibrate, clonazepam, medazepam) and non co-planar polychlorobiphenyls (PCBs; PCB101, 138, 180). Furthermore, we detected potent PXR activity in two types of water samples: passive polar organic compounds integrative sampler (POCIS) extracts from a river moderately impacted by agricultural and urban inputs and three effluents from sewage treatment works (STW). Fractionation of POCIS samples showed the highest PXR activity in the less polar fraction, while in the effluents, PXR activity was mainly associated with the dissolved water phase. Chemical analyses quantified several PXR-active substances (i.e., alkylphenols, hormones, pharmaceuticals, pesticides, PCBs, bisphenol A) in POCIS fractions and effluent extracts. However, mass-balance calculations showed that the analyzed compounds explained only 0.03% and 1.4% of biological activity measured in POCIS and STW samples, respectively. In effluents, bisphenol A and 4-tert-octylphenol were identified as main contributors of instrumentally derived PXR activities. Finally, the PXR bioassay provided complementary information as compared to estrogenic, androgenic, and dioxin-like activity measured in these samples. This study shows the usefulness of HG5LN-hPXR cells to detect PXR-active compounds in water samples, and further investigation will be necessary to identify the detected active compounds.

Keywords: Reporter bioassays; Endocrine disrupters; Passive sampling; Wastewater

Identification of a CYP3A form (CYP3A126) in fathead minnow (Pimephales promelas) and characterisation of putative CYP3A enzyme activity by Verena Christen; Daniel Caminada; Michael Arand; Karl Fent (pp. 585-595).

Cytochrome P450-dependent monooxygenases (CYPs) are involved in the metabolic defence against xenobiotics. Human CYP3A enzymes metabolise about 50% of all pharmaceuticals in use today. Induction of CYPs and associated xenobiotic metabolism occurs also in fish and may serve as a useful tool for biomonitoring of environmental contamination. In this study we report on the cloning of a CYP3A family gene from fathead minnows (Pimephales promelas), which has been designated as CYP3A126 by the P450 nomenclature committee (GenBank no. EU332792). The cDNA was isolated, identified and characterised by extended inverse polymerase chain reaction (PCR), an alternative to the commonly used method of rapid amplification of cDNA ends. In a fathead minnow cell line we identified a full-length cDNA sequence (1,863 base pairs (bp)) consisting of a 1,536 bp open reading frame encoding a 512 amino acid protein. Genomic analysis of the identified CYP3A isoenzyme revealed a DNA sequence consisting of 13 exons and 12 introns. CYP3A126 is also expressed in fathead minnow liver as demonstrated by reverse transcription PCR. Exposure of fathead minnow (FHM) cells with the CYP3A inducer rifampicin leads to dose-dependent increase in putative CYP3A enzyme activity. In contrast, inhibitory effects of diazepam treatment were observed on putative CYP3A enzyme activity and additionally on CYP3A126 mRNA expression. This indicates that CYP3A is active in FHM cells and that CYP3A126 is at least in part responsible for this CYP3A activity. Further investigations will show whether CYP3A126 is involved in the metabolism of environmental chemicals. Figure Induction of CYP3A activity by rifampicin and inhibition by diazepam in FHM cells

Keywords: Fathead minnow; Fish; Cytochrome P4503A; CYP3A; CYP3A126; Pharmaceuticals; Interaction of chemicals with CYP3A; Diazepam; Induction and inhibition of CYP3A

Time course of expression of the retinoid X receptor gene and induction of imposex in the rock shell, Thais clavigera, exposed to triphenyltin chloride by Toshihiro Horiguchi; Tomohiro Nishikawa; Yasuhiko Ohta; Hiroaki Shiraishi; Masatoshi Morita (pp. 597-607).

To examine the role of the retinoid X receptor (RXR) in the development of imposex in gastropods, we investigated the time course of expression of the RXR gene in various tissues (ctenidium, ovary or testis, digestive gland, penis-forming area or penis, and head ganglia) of female and male rock shells (Thais clavigera) exposed to triphenyltin (TPT) in a flow-through exposure system for 3 months. Accumulations of TPT in tissues were clearly observed in exposed individuals, whereas no accumulation of TPT was observed in the control groups. In females, 3-month exposure to TPT resulted in the development of imposex, and penis lengths in imposex-exhibiting females were significantly longer in small females (shell height <20 mm) than in large females (shell height ≥20 mm). RXR gene expression in the ovary, penis-forming area or penis, and head ganglia of females exposed for 3 months was significantly higher than expression in control females, and the highest RXR gene expression was found in the penis-forming area or penis. Moreover, RXR gene expression in the penis-forming area or penis of each female exposed to TPT seemed to be associated with an increase in penis length. In males, the ratio of penis length to shell height was significantly larger in the exposed groups than in the controls. Although RXR gene expression in males exposed for 3 months was not significantly higher than expression in control males in any tissues, the highest gene expression was observed in the penis of exposed males. These results suggest that RXR plays an important role in the development of male genitalia (i.e., penis and vas deferens) in gastropods, although RXR might also have other physiological functions. Figure Relationships between average penis length and RXR gene expression in penis-forming area/penis and ovary of female rock shells exposed to 500 ng/L of triphenyltin chloride (TPTCl) for 3 months in a flow-through system. TPT, triphenyltin. Bars in the upper and middle figures represent normalized RXR gene expression in ovary and penis-forming area/penis of females exposed to TPTCl, respectively. Dots or symbols in the bottom figure represent measured values of penis length of each female in the respective composite samples. RXR gene expression in the penis-forming area or penis of each female exposed to TPT seems to be associated with an increase in penis length, however, that in ovary does not.

Keywords: Imposex; Penis; Vas deferens; Organotin compounds; Rock shell; Retinoid X receptor (RXR)

Toxicities of nano zinc oxide to five marine organisms: influences of aggregate size and ion solubility by Stella W. Y. Wong; Priscilla T. Y. Leung; A. B. Djurišić; Kenneth M. Y. Leung (pp. 609-618).

Nano zinc oxide (nZnO) is increasingly used in sunscreen products, with high potential of being released directly into marine environments. This study primarily aimed to characterize the aggregate size and solubility of nZnO and bulk ZnO, and to assess their toxicities towards five selected marine organisms. Chemical characterization showed that nZnO formed larger aggregates in seawater than ZnO, while nZnO had a higher solubility in seawater (3.7 mg L⁻¹) than that of ZnO (1.6 mg L⁻¹). Acute tests were conducted using the marine diatoms Skeletonema costatum and Thalassiosia pseudonana, the crustaceans Tigriopus japonicus and Elasmopus rapax, and the medaka fish Oryzias melastigma. In general, nZnO was more toxic towards algae than ZnO, but relatively less toxic towards crustaceans and fish. The toxicity of nZnO could be mainly attributed to dissolved Zn²⁺ ions. Furthermore, molecular biomarkers including superoxide dismutase (SOD), metallothionein (MT) and heat shock protein 70 (HSP70) were employed to assess the sublethal toxicities of the test chemicals to O. melastigma. Although SOD and MT expressions were not significantly increased in nZnO-treated medaka compared to the controls, exposure to ZnO caused a significant up-regulation of SOD and MT. HSP70 was increased two to fourfold in all treatments indicating that there were probably other forms of stress in additional to oxidative stress such as cellular injury.

Keywords: Zinc oxide; Algae; Crustacean; Medaka; Biomarker

Genotoxic potential of TiO₂ on bottlenose dolphin leukocytes by Margherita Bernardeschi; Patrizia Guidi; Vittoria Scarcelli; Giada Frenzilli; Marco Nigro (pp. 619-623).

Titanium dioxide is extensively used in a variety of products, including industrial materials and cosmetics. Studies mainly performed on human cell lines and in vivo exposure on experimental animals have raised concern about the toxic effects of ultrafine titanium dioxide; however, scarce information is available about its impact on aquatic life. The aim of this article was to assess the genotoxic potential of TiO₂ (anatase and rutile) on bottlenose dolphin leukocytes. Blood samples were obtained from four male and one female specimens reared at the Adriatic SeaWorld “Oltremare” (Riccione, Italy). Leukocytes were isolated by the lyses procedure and in vitro exposed to TiO₂ in RPMI. Experimental solutions were sonicated immediately before dosing the cells. Three exposure times (4, 24 and 48 h) and three doses (20, 50 and 100 µg/ml) were tested. Genotoxicity was detected by the single-cell gel electrophoresis (or comet assay) at pH ≥ 13, assessing single/double-strand breaks and alkali-labile sites. Cytotoxicity was also detected by the Trypan blue exclusion method. Results showed that both the crystalline forms of TiO₂ were genotoxic for bottlenose dolphin leukocytes, with a statistically significant increase of DNA fragmentation after exposure to 50 and 100 µg/ml for 24 and 48 h. Although preliminary, these are the first data regarding the genetic susceptibility of toothed cetaceans toward an “emerging” pollutant, such as TiO₂ particles.

Keywords: Titanium dioxide; Tursiops truncatus ; Bottlenose dolphin; Genotoxicity; Comet assay

Genotoxic potential of TiO₂ on bottlenose dolphin leukocytes by Margherita Bernardeschi; Patrizia Guidi; Vittoria Scarcelli; Giada Frenzilli; Marco Nigro (pp. 619-623).

Keywords: Titanium dioxide; Tursiops truncatus ; Bottlenose dolphin; Genotoxicity; Comet assay

Differential expression of vitellogenin and oestrogen receptor genes in the liver of zebrafish, Danio Rerio by Xiang Meng; Chris Bartholomew; John A. Craft (pp. 625-630).

Environmental oestrogens are responsible for adverse effects in fish that affect reproduction. Availability of model fish to study the differential effects of endogenous and exogenous oestrogens and to test for oestrogenic activity of chemicals would be advantageous. Zebrafish could provide such a model, but the organisation and expression of vitellogenins (VTGs) and oestrogen receptors (ERs) are not completely understood. VTGs are synthesised in the liver and provide a sensitive biomarker of oestrogenic activity since they are thought to be under the regulation of the ER. There are multiple genes for VTGs and an in silico analysis of their distribution in the Zebrafish genome has identified six genes: VTG-1, VTG-2, VTG-4, VTG-5, VTG-7 located on chromosome 22 and VTG-3 on chromosome 11. VTG-specific, quantitative, real-time, reverse-transcriptase polymerase chain reaction assays were developed and used to measure differential expression in the livers of mature male and female zebrafish. Following normalisation in female fish, relative expression of VTG-5 mRNA is highest and is 1.3×, 1.6× and 2× higher than VTG-4, VTG-2 and VTG-1, respectively, while expression of VTG-3 and VTG-7 is very low. Expression of VTGs in male fish was either undetectable or very low (VTG-4 and VTG-5). ERα and ERβ2 were expressed at higher levels than ERβ1 in females, but only ERβ2 was expressed in appreciable quantity in males. Expression of ERα in males was significant but only at the limit of detection (<0.1% of female fish), while ERβ1 could not be detected. The very low level of expression of ERα in males raises questions about the accepted mechanism of oestrogenic induction of VTG in male fish.

Keywords: Environmental oestrogens; Zebrafish; Vitellogenins; Oestrogen receptors; Real-time PCR; PCR; Bioanalytical methods; Biological samples; Forensics/toxicology; Nucleic acids (DNA | RNA); Pesticides/endocrine disruptors

Differential expression of vitellogenin and oestrogen receptor genes in the liver of zebrafish, Danio Rerio by Xiang Meng; Chris Bartholomew; John A. Craft (pp. 625-630).

Effects of 17β-trenbolone in male eelpout Zoarces viviparus exposed to ethinylestradiol by Yohana M. Velasco-Santamaría; Steffen S. Madsen; Poul Bjerregaard; Bodil Korsgaard (pp. 631-640).

To evaluate the interaction between 17β-trenbolone (TB) and 17α-ethinylestradiol (EE2), male eelpout, Zoarces viviparus, was exposed for 21 days (April to May 2008) to 5 ng l⁻¹ EE2 and 5 or 20 ng l⁻¹ TB, separately or in combination in a flow-through SW system. The effects on hepatosomatic (HSI) and gonadosomatic index (GSI), plasma vitellogenin (Vtg) concentration, gonadal histology, hepatic and testicular Vtg mRNA and estrogen receptor (ERα) mRNA expression were investigated. No effects on HSI were observed. A significant decrease was observed in the GSI of all males exposed to EE2 (<0.7%) when compared to controls (1.4%). Histological alterations and immature stages were observed in the testis of all exposed males; however, males exposed to EE2 were the most affected. Increased tubule number and proportionally decreased tubule diameter were observed in the testis of all EE2 groups. No effects in Vtg mRNA expression were observed in the testis; however, a significant decrease in testis ERα mRNA was observed in males exposed to 20 ng l⁻¹ TB. The groups exposed to EE2 showed a significant increase in plasma Vtg (>300-fold), hepatic Vtg mRNA (>450-fold), and ERα mRNA (>100-fold) when compared to controls. This study shows that lower concentrations of 17β-trenbolone are unable to counteract the EE2 estrogenic effects when the exposure is simultaneous. Figure Microphotograph of testis eelpout (Zoarces viviparus) after 21 days exposure to solvent control (left side) and 5 ng l^-1 EE² (right side). The squares correspond to an area of 500 μm² and the drawing lines show the longer diameter of the tubules. Sections were 5 μm thickness and stained with H&E.

Keywords: Eelpout; Histology; RT–PCR; Vitellogenin; Trenbolone; Ethinylestradiol

Effects of 17β-trenbolone in male eelpout Zoarces viviparus exposed to ethinylestradiol by Yohana M. Velasco-Santamaría; Steffen S. Madsen; Poul Bjerregaard; Bodil Korsgaard (pp. 631-640).

Keywords: Eelpout; Histology; RT–PCR; Vitellogenin; Trenbolone; Ethinylestradiol

Developmental toxicity of benzotriazole in the protochordate Ciona intestinalis (Chordata, Ascidiae) by Eniko Kadar; Sarah Dashfield; Thomas H. Hutchinson (pp. 641-647).

Benzotriazoles (BT) are applied as anticorrosive and de-icing agents and have been detected in a variety of aquatic ecosystems and municipal wastewater effluents. We have assessed the developmental effects of benzotriazole (CAS number 95-14-7) to the marine invertebrate Ciona intestinalis (Chordata, Ascidiae). At 15 ± 1 °C, the 24 h No-Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) values based on embryo morphological development were 100 and >100 mg L⁻¹, respectively (nominal concentration under static conditions). After 48 h, the NOEC and LOEC values were 10 and 32 mg L⁻¹, respectively. Light and electron microscopy studies on benzotriazole-exposed larva indicated that the primary target cells were the extra-embryonic test cells, which are known to play a significant apoptotic role during ascidian metamorphosis. The visible decline of test cells in benzotriazole-exposed larvae raises the possibility that the compound interferes with the regulation of embryo development in protochordates such as C. intestinalis. Further research is warranted to assess the potential longer term sublethal impacts of benzotriazole in aquatic organisms.

Keywords: Embryo assay; Emerging contaminants; In vitro fertilisation; Test cells

Developmental toxicity of benzotriazole in the protochordate Ciona intestinalis (Chordata, Ascidiae) by Eniko Kadar; Sarah Dashfield; Thomas H. Hutchinson (pp. 641-647).

Keywords: Embryo assay; Emerging contaminants; In vitro fertilisation; Test cells

Effects on feeding rate and biomarker responses of marine mussels experimentally exposed to propranolol and acetaminophen by Montserrat Solé; Jennifer P. Shaw; Patricia E. Frickers; James W. Readman; Thomas H. Hutchinson (pp. 649-656).

Environmental risk assessments of human pharmaceuticals and other ‘emerging contaminants’ should integrate both population-relevant endpoints and biomarkers of potential modes of action in a range of species. Adult Mytilus galloprovincialis were exposed to the beta-adrenergic receptor blocker propranolol or to the anti-inflammatory drug acetaminophen (paracetamol), both commonly used therapeutic drugs present in aquatic ecosystems. Mussels were exposed under semi-static conditions for 10 days to either acetaminophen (CAS number 103-90-2; mean measured concentrations 23 and 403 µg/L) or propranolol hydrochloride (CAS number 318-98-9; mean measured propranolol concentrations 11 and 147 µg/L) at 15 ± 1 °C sea water. Feeding rate was assessed as an indicator of general toxicity. For propranolol, the 10-day no-observed effect concentration (^{feeding rate}NOEC) and lowest observed effect concentration (^{feeding rate}LOEC) were 11 and 147 µg/L, respectively. For acetaminophen, feeding rate was increased at both 23 and 403 µg/L, suggesting a 10-day ^{feeding rate}NOEC of 403 µg/L. Primarily, phase I carboxylesterase (CbE), phase II glutathione S-transferase (GST) and the anti-oxidant catalase activities were evaluated in digestive gland. Gill GST and acetylcholinesterase (AChE) activities were also measured. Lipid peroxidation (LPO) levels were measured in both tissues to assess oxidative stress. Some enzymatic activities in liver were also reduced after propranolol exposure whilst acetaminophen enhanced them (CbE p < 0.05). Acetaminophen exposure significantly increased hepatic LPO levels and inhibited AChE activity in gill (10-day NOEC and LOEC of 23 and 403 µg/L, respectively), whereas propranolol (11 µg/L) enhanced gill GST.

Keywords: Mytilus galloprovincialis ; Propranolol; Acetaminophen; Feeding rate; Biochemical responses

Uptake and biological responses to nano-Fe versus soluble FeCl₃ in excised mussel gills by Enikö Kádár; David M. Lowe; Montserrat Solé; Andrew S. Fisher; Awadhesh N. Jha; James W. Readman; Thomas H. Hutchinson (pp. 657-666).

Nano-Fe particle uptake was experimentally examined in vitro using excised gills and blood cells of the edible blue mussel Mytilus sp. Whole gills were exposed to both Fe₂O₃ nanoparticles and a solution of the hydrated FeCl₃ salt, for up to 12 h, and blood cells for 30 min. Equimolar Fe⁺³ in the nano- and the soluble form was estimated under the assumption of dense spherical particles accommodating the same number of Fe⁺³ as in the dissolved salt solution, namely: 1,000 μg L⁻¹ Fe₂O₃ equivalent to 100 μg L⁻¹ FeCl₃·6H₂O. Putative toxic impact of nano-Fe in gill epithelia and blood cells was assessed by an array of techniques including light- and electron microscopy, biomarkers for oxidative stress (lipid peroxidation levels), neurotoxic effects (acetylcholinesterase activity) and cytotoxicity (neutral red retention). Total and filtered fractions (20 and 200 nm, respectively) of Fe were analysed by ICP-OES. Our results provide evidence for the following: (1) much of both the soluble (95%) and the nano-Fe (90%) were removed from the water column within 12 h; (2) dissolved- and nano-Fe seemed to follow different routes of uptake within the gill epithelium; (3) both nano-Fe and soluble FeCl₃ caused similar impairment of lysosomal stability in circulating blood cells; (4) lipid peroxidation in gills exposed to the two distinct forms of Fe was increased, while acetylcholinesterase activity was unaffected. In these short-term in vitro studies, there appears to be little difference in toxic response between exposure to the Fe salt and the nano-Fe indicating that, in this case, the nanoparticles do not invoke special properties affecting biological function in gills. However, with the use of nano-Fe as a food additive, clearly longer-term in vivo studies are warranted.

Keywords: Engineered nanoparticles (ENPs); Bivalve; Haemocyte; Oxidative stress; Neurotoxicity; Cytotoxicity

Immuno-interferometric sensor for the detection of influenza A nucleoprotein by Leslie R. Farris; Nan Wu; Wenhui Wang; Lisa-Jo A. Clarizia; Xingwei Wang; Melisenda J. McDonald (pp. 667-674).

Influenza A virus, both seasonal and pandemic, has the potential to cause rampant devastating disease around the world. The most relied upon methods of viral detection require days, skilled workers, and laboratory settings to complete properly. Here, we report two methods for the detection of the nucleoprotein from inactivated influenza A (IFA-NP), a patented polymer–protein antibody orientation immuno-method, termed ALYNGSA, and a newly fabricated optical label-free Fabry–Perot interferometric immunosensor. The ALYGNSA assay for IFA-NP had a level of detection below 5 μg/mL of inactivated virus sample. The label-free detection through Fabry–Perot interferometry with the ALYGNSA orientation yielded an improved sensitivity to 1 μg/mL over the fluorescence sandwich assay alone. Characterization of the detection surface by fluorescence microscopy and non-contact AFM corroborated interferometry results. The resulting label-free detection method has the prospective for adaptation into a portable multi-chip sensor capable of real-time in situ detection of influenza A virus.

Keywords: Influenza A nucleoprotein; Biosensor; Immunoassay; Interferometry; Laser scanning confocal microscopy; Atomic force microscopy; Optical sensors; Immunoassays/ELISA; Influenza A

Immuno-interferometric sensor for the detection of influenza A nucleoprotein by Leslie R. Farris; Nan Wu; Wenhui Wang; Lisa-Jo A. Clarizia; Xingwei Wang; Melisenda J. McDonald (pp. 667-674).

Keywords: Influenza A nucleoprotein; Biosensor; Immunoassay; Interferometry; Laser scanning confocal microscopy; Atomic force microscopy; Optical sensors; Immunoassays/ELISA; Influenza A

Immunoassay detection in a perfluorocarbon emulsion oxygen therapeutic by Rebecca E. Barlag; H. Brian Halsall; William R. Heineman (pp. 675-680).

The effect of a perfluorocarbon emulsion oxygen therapeutic (PEOT) on detecting theophylline was explored using a commercial EMIT® (enzyme multiplied immunoassay technique) immunoassay. The EMIT technique is based on a colorimetric reaction, the product of which can be measured spectrophotometrically. The intent was to determine whether the presence of PEOT interferes with this detection. We found that the immunoassay yields excellent quantitative data in the therapeutic range (10–20 ppm theophylline) in 2–10% PEOT, but as the amount of PEOT in the sample increases, the accuracy of the detection method decreases.

Keywords: Immunoassay; Perfluorocarbon; Spectrophotometry; Theophylline

Immunoassay detection in a perfluorocarbon emulsion oxygen therapeutic by Rebecca E. Barlag; H. Brian Halsall; William R. Heineman (pp. 675-680).

Keywords: Immunoassay; Perfluorocarbon; Spectrophotometry; Theophylline

Polymer–protein-enhanced fluoroimmunoassay for prostate-specific antigen by Brian C. Mackness; Sinang Chourb; Leslie R. Farris; Melisenda J. McDonald (pp. 681-686).

Prostate-specific antigen (PSA) is a serum glycoprotein overproduced in prostate cancer, the total of which is comprised of two major forms, free and complexed. The common method for measuring of PSA is an Enzyme-linked immunosorbent assay (ELISA). Limits of detection using commercial PSA ELISA kits for free and total PSA were determined in our laboratory to be 1 and 10 ng/mL, respectively. A value of 0.10 was obtained for the free to total PSA ratio, a ratio of 0.25 being indicative of prostate cancer. A possible improvement in the sensitivity and detection limits of free and total PSA may be achieved by the ALYGNSA system (Clarizia et al., Anal Bioanal Chem 393:1531–1538, 2009). This fluorescent assay system employed a selective polymer biolinker system proven to enhance primary antibody orientation. Using this system, free and total PSA detection limits of 0.13 and 0.63 ng/mL, respectively, were realized. This amounted to an 8- and 15-fold improvement in detection limits for free and total PSA, respectively. A free to total PSA ratio of 0.20 was maintained in this study and may be useful for definitive diagnosis of prostate, as well as, other cancers.

Keywords: Prostate-specific antigen (PSA); Free to total PSA ratio; Cancer biomarker; ELISA; ALYGNSA; Immunoassay

Polymer–protein-enhanced fluoroimmunoassay for prostate-specific antigen by Brian C. Mackness; Sinang Chourb; Leslie R. Farris; Melisenda J. McDonald (pp. 681-686).

Keywords: Prostate-specific antigen (PSA); Free to total PSA ratio; Cancer biomarker; ELISA; ALYGNSA; Immunoassay

Development of a chemiluminescent ELISA and a colloidal gold-based LFIA for TNT detection by S. Girotti; S. Eremin; A. Montoya; M. J. Moreno; P. Caputo; M. D’Elia; L. Ripani; F. S. Romolo; E. Maiolini (pp. 687-695).

To identify the explosive used in a terrorist attack, or to obtain an early sign of environmental pollution it is important to use simple and rapid assays able to detect analytes at low levels, possibly on-site. This is particularly true for TNT (2,4,6-trinitrotoluene), one of the most employed explosives in the 20th century and at the same time, because of its toxicity, a well known pollutant. In this work we describe the development of an indirect competitive ELISA with chemiluminescent detection (CL-ELISA) and of a lateral-flow immunoassay (LFIA) based on colloidal gold nanoparticle labels. A commercially available monoclonal antibody was used and 13 specially synthesized conjugates were tested. We optimized the assay by determining the optimal concentration of monoclonal antibody and conjugates and the influence of various non-specific factors such as: tolerance to organic solvents at different concentrations, the washing and competitive step time, and the cross-reactivity with related compounds. The sensitivity and reproducibility of the CL-ELISA were good (LOD and IC₅₀ values in the ng mL⁻¹ range, and CV value about 7%). It has been applied to real samples of various materials involved in a controlled explosion of an “improvised explosive device”. Three extraction procedures were tested on these samples, all employing methanol as the solvent. The lateral flow immunoassay (LFIA), developed by using the same immunoreagents, reached a detection limit of 1 μg mL⁻¹ when tested on the same samples analysed by CL-ELISA. Figure LFIA of TNT standard at different concentrations: 1) No TNT; 2) 100 g mL⁻¹ TNT; 3) 1 g mL⁻¹ TNT;4) 0.1 g mL⁻¹ TNT.

Keywords: 2,4,6-Trinitrotoluene (TNT); Chemiluminescence; ELISA; LFIA; Immunoassay

Electrochemical deposition of silicate–cetyltrimethylammonium bromide nanocomposite film on glassy carbon electrode for sensing of methyl parathion by Shengcheng Xia; Junfeng Zhang; Chunya Li (pp. 697-705).

A novel electrochemical sensor for methyl parathion based on silicate– cetyltrimethylammonium bromide nanocomposite film has been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry. Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased. Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship between the peak current and methyl parathion concentration was obtained in the range from 1.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol L⁻¹ with a detection limit of 1.04 × 10 ⁻⁸ mol L⁻¹ (S/N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in real samples. Figure Scheme for the fabrication of the silicate-CTAB film modified glassy carbon electrode and its application in electrochemical sensing of methyl parathion.

Keywords: Silicate; Cetyltrimethylammonium bromide; Methyl parathion; Electrochemical deposition; Voltammetry

Magnetic-based purification system with simultaneous sample washing and concentration by Qasem Ramadan; Ting Ting Lau; Shihan Bryan Ho (pp. 707-714).

Simultaneous washing and concentration of magnetic microparticles was demonstrated using a rotational magnetic system under a continuous-flow condition. The rotation of periodically arranged permanent magnets close to a fluidic channel carrying a suspension of magnetic particles allows the trapping and releasing of particles along the fluidic channel in a periodic manner. Each trapping and releasing event resembles one washing cycle in conventional biological assays. Concentration efficiencies of 99.75 ± 0.083% at a flow rate of 200 µl/min and 88.10 ± 3.17% at a flow rate of 1,000 µl/min and a purification efficiency of 99.10 ± 4.3% at a flow rate of 900 µl/min were achieved.

Keywords: Continuous flow; Washing; Separation; Magnetic particles

Magnetic-based purification system with simultaneous sample washing and concentration by Qasem Ramadan; Ting Ting Lau; Shihan Bryan Ho (pp. 707-714).

Keywords: Continuous flow; Washing; Separation; Magnetic particles

A microfluidic device with integrated fluorimetric detection for flow injection analysis by Alexandre Fonseca; Ivo M. Raimundo Jr.; Jarbas J. R. Rohwedder; Renato S. Lima; Mário C. Ugulino Araújo (pp. 715-723).

This work describes the development of flow analysis microsystems with integrated fluorimetric detection cells. Channels (width of 300–540 µm and depth of 200–590 µm) were manufactured by deep-UV lithography in urethane–acrylate (UA) resin. Plastic optical fibers (diameter of 250 µm) were coupled to a 2.0-mm-long detection channel in order to guide the excitation radiation from an LED (470 nm) and collect the emitted radiation at a right angle towards a photomultiplier. A single-line miniaturized system, with a total internal volume of 10.4 μL, was evaluated by means of standard fluorescein solutions (0.53–2.66 µmol L⁻¹, pH 8.5). The analytical signals presented a linear relationship in the concentration range studied, with a relative standard deviation of 1.9% (n = 5), providing a detection limit of 0.37 µmol L⁻¹ and an analytical frequency of 60 samples/h, using a flow rate of 60 µL min⁻¹. Optical microscopy images and videos acquired in real time for the hydrodynamic injection of 130 and 320 nL of sample solutions indicated the good performance of the proposed sampling strategy. Another microsystem with a total internal volume of 38 µL was developed, incorporating a confluence point for two solutions. This device was applied to the determination of the total concentration of Ca²⁺ and Mg²⁺ in commercial mineral waters using the calcein method. Microscopy images and videos demonstrated the mixing efficiency of the solutions in the microchannels. A linear relationship was observed for the analytical signal in the Ca²⁺ concentration range from 25 to 125 µmol L⁻¹, with relative standard deviations of 3.5%. The analysis of mineral waters with the proposed system provided results that did not differ significantly from those obtained by the EDTA titration method at a confidence level of 95%. These results demonstrate the viability of developing micro flow injection systems with an integrated fluorimetric detection cell. Figure Microfluidic device for flow injection analysis

Keywords: µ-TAS; Microfluidics; Flow analysis; UV lithography; Fluorimetry

Determination of accessible amino groups on surfaces by chemical derivatization with 3,5-bis(trifluoromethyl)phenyl isothiocyanate and XPS/NEXAFS analysis by Nora Graf; Andreas Lippitz; Thomas Gross; Falko Pippig; Andreas Holländer; Wolfgang E. S. Unger (pp. 725-738).

The determination of amino groups on surfaces capable of binding biomolecules is important for the understanding and optimization of technologically relevant coupling processes. In this study, three different types of amino-functionalized model surfaces, amino thiolate on Au, amino siloxane on Si, and polyethylene (PE) foils and films reacted with 1,2-diaminoethane (DAE) were derivatized with 3,5-bis(trifluoromethyl)phenyl isothiocyanate. Subsequently, these samples were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The determination of amino groups by this analytical approach allows gaining insight into the availability of groups on surfaces that can actually serve as attachment sites for biomolecules in technical applications. In the case of the amino thiolate on Au, almost 90% of the expected amino groups were detected by CD-XPS. Investigation of the amino siloxane films revealed lower yields for the derivatization reaction in the order of 30%. The lowered reaction yields are thought to be due to interactions between the amino siloxane’s amino and silanol groups or the underlying substrate, making them inaccessible to the derivatization agent. The aminated PE samples are characterized by a complex surface chemistry and structure, and reaction yields of the derivatization reaction cannot be unequivocally derived. However, 1–3% of the total carbon atoms in the surface layer were found to be bound to amino groups accessible to the derivatization agent. It can be concluded that, depending on the detailed character of the investigated amino-terminated surface, the amount of amino groups accessible to CD-XPS can be substantially lower than the total amount of amino groups present at the surface.

Keywords: XPS/ESCA; NEXAFS/XANES; CD-XPS; Amino-functionalized surfaces; SAM

Human breath analysis: methods for sample collection and reduction of localized background effects by Audrey N. Martin; George R. Farquar; A. Daniel Jones; Matthias Frank (pp. 739-750).

Solid-phase microextraction (SPME) was applied, in conjunction with gas chromatography–mass spectrometry, to the analysis of volatile organic compounds (VOCs) in human breath samples without requiring exhaled breath condensate collection. A new procedure, exhaled breath vapor (EBV) collection, involving the active sampling and preconcentration of a breath sample with a SPME fiber fitted inside a modified commercial breath-collection device, the RTube™, is described. Immediately after sample collection, compounds are desorbed from the SPME fiber at 250 °C in the GC-MS injector. Experiments were performed using EBV collected at −80 °C and at room temperature, and the results compared to the traditional method of collecting exhaled breath condensate at −80 °C followed by passive SPME sampling of the collected condensate. Methods are compared in terms of portability, ease-of-use, speed of analysis, and detection limits. The need for a clean air supply for the study subjects is demonstrated using several localized sources of VOC contaminants including nail polish, lemonade, and gasoline. Various simple methods to supply clean inhaled air to a subject are presented. Chemical exposures are used to demonstrate the importance of providing cleaned air (organic vapor respirator) or an external air source (tubing stretched to a separate room). These techniques allow for facile data interpretation by minimizing background contaminants. It is demonstrated herein that this active SPME breath-sampling device provides advantages in the forms of faster sample collection and data analysis, apparatus portability and avoidance of power or cooling requirements, and performance for sample collection in a contaminated environment. Figure Extracted ion chromatograms (XIC m/z 93) of breath samples from a single subject (EBV-RT). One sample was collected over 125 mL of lemonade with no modification to the inhaled air (red trace, top) and another sample was collected over 125 mL of lemonade using a respirator (blue trace, bottom). Peaks labeled are identified as monoterpenes and monoterpene alcohols, flavor ingredients present in lemonade.

Keywords: Bioanalytical methods; Breath analysis; GC-MS; VOC; Breath condensate

Human breath analysis: methods for sample collection and reduction of localized background effects by Audrey N. Martin; George R. Farquar; A. Daniel Jones; Matthias Frank (pp. 739-750).

Keywords: Bioanalytical methods; Breath analysis; GC-MS; VOC; Breath condensate

LC-ESI MS/MS quantification of atropine and six other antimuscarinic tropane alkaloids in plasma by Harald John; Tobias Binder; Hans Höchstetter; Horst Thiermann (pp. 751-763).

We have developed and validated a quantitative liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI MS/MS) procedure for the simultaneous determination of seven natural and semisynthetic tropane alkaloids in plasma: atropine (d-hyoscyamine/l-hyoscyamine), cocaine, homatropine, ipratropium, littorine, N-butylscopolamine, and scopolamine. Plasma and serum samples were precipitated for deproteinization (recovery 88–94%), followed by reversed-phase-based liquid chromatography prior to positive electrospray ionization for detection by multiple reaction monitoring using a linear ion trap quadrupole mass spectrometer. All analytes were quantified using cocaine-d3 as an internal standard suitable and reliable for robust, precise (coefficient of variation 2–13%), and accurate (87–122%) measurement within a linear range of 3 orders of magnitude (0.05–50 ng/ml plasma). The method was exemplarily applied to stability studies in phosphate-buffered saline, human serum, and rabbit serum. Each alkaloid was incubated separately and samples were taken at distinct incubation time points. Supernatants of diverse alkaloids at corresponding time points were pooled and subjected to simultaneous LC-ESI MS/MS quantification. This combinatorial analysis design allowed us to analyze the stability of samples with a drastically reduced number of chromatographic runs. In the presence of rabbit serum, all tropane alkaloids tested were degraded significantly within minutes to hours, with the exception of the stable semisynthetic compounds ipratropium and N-butylscopolamine. In contrast, in the presence of equal concentrations of human serum, no degradation was observed for any of the compounds, with the exception of cocaine. Relevant enzymes involved in enzymatic degradation are discussed.

Keywords: Antimuscarinic agents; Atropinesterase; Hyoscyamine; Rabbit serum; Tropane alkaloids

LC-ESI MS/MS quantification of atropine and six other antimuscarinic tropane alkaloids in plasma by Harald John; Tobias Binder; Hans Höchstetter; Horst Thiermann (pp. 751-763).

Keywords: Antimuscarinic agents; Atropinesterase; Hyoscyamine; Rabbit serum; Tropane alkaloids

A probabilistic approach to heroin signatures by D. Brynn Hibbert; Danielle Blackmore; Jianfeng Li; Diako Ebrahimi; Michael Collins; Sasha Vujic; Paul Gavoyannis (pp. 765-773).

The probability density functions of amount ratios of compounds (total codeine/total morphine, 6-monoacetylemorphine/total morphine, papaverine/total morphine, and noscapine/total morphine) from the analysis of seized heroin, originating from known world regions (South East Asia, South West Asia, South America, Mexico) allows calculation of likelihood ratios for ‘unknown’ samples. Application of Bayes Theorem with a suitable prior probability, for example the frequency of a particular region in the database, leads to the probability that a particular profile comes from a given target region. Data from 2549 seizures of heroin at Australia’s border illustrates the method, and results are compared with simple HS1 ratio approaches for assigning geographical origin. The method can be implemented in a spreadsheet and gives more refined intelligence of the origins of seized drugs than simple ranges. Figure Histograms of frequencies of values of the codeine to morphine amount ratio by region determined by the UN HS1 in the NMI database.

Keywords: Heroin signature program; Heroin analysis; Illicit drug analysis; Drug identification; Bayesian classification; Bayes’ theorem; Heroin; Morphine; Diacetyl morphine; Monoacetyl morphine; Codeine; Likelihood; Probability density function

A probabilistic approach to heroin signatures by D. Brynn Hibbert; Danielle Blackmore; Jianfeng Li; Diako Ebrahimi; Michael Collins; Sasha Vujic; Paul Gavoyannis (pp. 765-773).

Separation of peptides by HPLC using a surface-confined ionic liquid stationary phase by K. R. Chitta; D. S. Van Meter; A. M. Stalcup (pp. 775-781).

A butylimidazolium bromide surface-confined ionic liquid stationary phase was synthesized in-house. The synthesized phase was investigated for the separation of five peptides (Gly-Tyr, Val-Tyr-Val, leucine enkephalin, methionine enkephalin, and angiotensin-II). The peptides were successfully separated in less than 5 min. The effect of trifluoroacetic acid (TFA) on the separation of peptides was evaluated with results confirming that TFA was not acting as ion-pairing agent in separation of peptides on this phase.

Keywords: Peptides; Retention mechanisms; Surface-confined ionic liquids; HPLC; Separations/theory

Separation of peptides by HPLC using a surface-confined ionic liquid stationary phase by K. R. Chitta; D. S. Van Meter; A. M. Stalcup (pp. 775-781).

Keywords: Peptides; Retention mechanisms; Surface-confined ionic liquids; HPLC; Separations/theory

Improved liquid chromatography–tandem mass spectrometry method in clinical utility for the diagnosis of Cushing’s syndrome by Bonnie Mei-Wah Fong; Sidney Tam; Kelvin Sze-Yin Leung (pp. 783-790).

Determination of urinary free cortisol is one of the first lines in screening for the diagnosis of Cushing’s syndrome where its measurement is mostly done by immunoassay. Although easy to perform, immunoassays suffer from the problem of assay interferences and are unable to measure cortisone levels. To enhance such techniques for clinical diagnosis, an improved liquid chromatography–tandem mass spectrometric (LC–MS/MS) method was developed for the simultaneous determination of urinary free cortisol and cortisone. The leftover urine samples from immunoassay were collected and subjected to facile solid-phase extraction cleanup. In the analysis of 130 urine samples from patients, 65 (50%) were found to have elevated urinary free cortisol (UFC) by immunoassay; but only 13 (10.8%) were found to have elevated UFC by this improved LC–MS/MS method. Nine out of the 13 patients, which showed elevated UFC by LC–MS/MS, were surgically confirmed to have Cushing’s syndrome/disease. By setting a two times upper limit as a cut-off, the immunoassay gave a positive predictive value of 43.5%, whilst by using the improved method, a positive predictive value of 90% was obtained. Although several tests have been used extensively in first line screening for the diagnosis of Cushing’s syndrome, none has ever shown with full capability of distinguishing all cases of Cushing’s syndrome from normal and/or obese individuals. This method has shown superior analytical advantages over existing immunoassay type in terms of sensitivity, specificity and capability to diagnose Cushing’s syndrome. Comparison between existing spectrometric methods, the reported developed method shown here, provides a simpler sample preparation procedure and meets with the high throughput demand of clinical laboratories.

Keywords: Cushing’s syndrome; Liquid chromatography–tandem mass spectrometry; Immunoassay

Development and validation of a simultaneous extraction procedure for HPLC-MS quantification of daptomycin, amikacin, gentamicin, and rifampicin in human plasma by Lorena Baietto; Antonio D’Avolio; Francesco Giuseppe De Rosa; Silvia Garazzino; Marianna Michelazzo; Giusi Ventimiglia; Marco Siccardi; Marco Simiele; Mauro Sciandra; Giovanni Di Perri (pp. 791-798).

A simultaneous extraction method to measure daptomycin, amikacin, gentamicin, and rifampicin in human plasma, by high-performance liquid chromatography, was developed and validated. The method involved a rapid sample preparation by protein precipitation with acetonitrile followed by direct injection into a high-performance liquid chromatography system coupled with mass detection. Drug retention times were 10.00 ± 0.25, 2.00 ± 0.25, 3.50 ± 0.25, 11.50 ± 0.25, and 12.50 ± 0.25 min for daptomycin, amikacin, gentamicin, rifampicin, and quinoxaline, respectively. Good linearity (mean r ² = 0.998) was obtained for all drugs quantified over the range of clinically relevant concentrations in human plasma and the use of the internal standard quinoxaline improves accuracy (RSD% <14.9%) and intra-day (RSD% <11.56) and inter-day (RSD% <12.10) precision for the analytical procedure. The limits of quantification for daptomycin, amikacin, gentamicin, and rifampicin were 1.56, 2.34, 0.63, 0.63 μg/ml, respectively. Moreover, the addition of ion pair trifluoroacetic acid in the sample allowed the majority of gentamicin and amikacin separation. A rapid, specific, sensitive, accurate, and reproducible HPLC method was developed and validated to measure daptomycin, amikacin, gentamicin, and rifampicin in human plasma. This method is suitable for clinical pharmacokinetic studies.

Keywords: Daptomycin; Amikacin; Gentamicin; Rifampicin; HPLC-MS; Therapeutic drug monitoring

Investigation of urinary steroid metabolites in calf urine after oral and intramuscular administration of DHEA by Ilse Becue; Christof Van Poucke; Jeroen C. W. Rijk; Toine F. H. Bovee; Michel Nielen; Carlos Van Peteghem (pp. 799-808).

DHEA (3β-hydroxy-androst-5-en-17-one) is a natural steroid prohormone. Despite a lack of information on the effect, DHEA and other prohormones are frequently used as a food supplement by body-builders. DHEA is suspected for growth promoting abuse in cattle as well. Considering the latter, urine samples from a previous exposure study in which calves were exposed to 1 g DHEA per day for 7 days, were used. The calves were divided in three groups: one orally treated, one intramuscularly injected, and a control group. The effect of this treatment on the urinary profile of several precursors and metabolites of DHEA was investigated. Urine samples were collected several days before and during the 7 days of administration and were submitted to a clean-up procedure consisting of a separation of the different conjugates (free, glucuronidated, and sulfated forms) of each compound on a SAX column (Varian). An LC-MS/MS method was developed for the detection and quantification of several metabolites of the pathway of DHEA including 17α- and 17β-testosterone, 4-androstenedione, 5-androstenediol, pregnenolone, and hydroxypregnenolone. Elevated levels of DHEA, 5-androstenediol, and 17α-testosterone were observed in the free and sulfated fraction of the urine of the treated calves, thus indicating that the administered DHEA is metabolized mainly by the ∆⁵-pathway with 5-androstenediol as the intermediate. Sulfoconjugates of DHEA and its metabolites were found to constitute the largest proportion of the urinary metabolites. The free form was also present, but in a lesser extent than the sulfated form, while glucuronides were negligible.

Keywords: LC-MS/MS; DHEA; Metabolites; 5-androstenediol; Urine; Prohormones

Fumonisins determination in urine by LC-MS-MS by Liliana J. G. Silva; Angelina Pena; Celeste M. Lino; Mónica F. Fernández; Jordi Mañes (pp. 809-816).

The present work shows the optimization and validation results of an analytical methodology based on imunoaffinity clean-up (IAC) followed by liquid chromatography with tandem mass detection (LC-MS-MS) for the analysis of the mycotoxins fumonisin B₁ (FB₁) and B₂ (FB₂) in human urine samples, in order to evaluate fumonisins exposure in two Portuguese populations. As far as we know, imunoaffinity clean-up procedure was used, for the first time, in the analysis of fumonisins (FBs) in urine. Using this analytical methodology, the limit of quantification achieved was 10 ng mL⁻¹ for FB₁ and for FB₂. Recoveries were higher than 73.4% for fortification levels between 10 and 100 ng mL⁻¹ and intra-day and inter-day repeatibility were lower than 8.6%. The natural occurrence of FB₁ and FB₂ in 68 human urine samples obtained from the central zone of Portugal was studied. None of the studied samples presented detectable levels of FB₁ and FB₂.

Keywords: Fumonisin B₁ ; Fumonisin B₂ ; Biomarkers; Human urine; Liquid chromatography; Tandem mass detection

Fumonisins determination in urine by LC-MS-MS by Liliana J. G. Silva; Angelina Pena; Celeste M. Lino; Mónica F. Fernández; Jordi Mañes (pp. 809-816).

Keywords: Fumonisin B₁ ; Fumonisin B₂ ; Biomarkers; Human urine; Liquid chromatography; Tandem mass detection

Chiral HPLC analysis of venlafaxine metabolites in rat liver microsomal preparations after LPME extraction and application to an in vitro biotransformation study by Patrícia da Fonseca; Pierina Sueli Bonato (pp. 817-824).

A three-phase LPME (liquid-phase microextraction) method for the enantioselective analysis of venlafaxine (VF) metabolites (O-desmethylvenlafaxine (ODV) and N-desmethylvenlafaxine (NDV) in microsomal preparations is described for the first time. The assay involves the chiral HPLC separation of drug and metabolites using a Chiralpak AD column under normal-phase mode of elution and detection at 230 nm. The LPME procedure was optimized using multifactorial experiments and the following optimal condition was established: sample agitation at 1,750 rpm, 20 min of extraction, acetic acid 0.1 mol/L as acceptor phase, 1-octanol as organic phase and donor phase pH adjustment to 10.0. Under these conditions, the mean recoveries were 41% and 42% for (−)-(R)-ODV and (+)-(S)-ODV, respectively, and 47% and 48% for (−)-(R)-NDV and (+)-(S)-NDV, respectively. The method presented quantification limits of 200 ng/mL and it was linear over the concentration range of 200–5,000 ng/mL for all analytes. The validated method was employed to study the in vitro biotransformation of VF using rat liver microsomal fraction. The results demonstrated the enantioselective biotransformation of VF. Online Abstract Figure Chromatogram showing the chiral metabolites N-desmethylvenlafaxine (peaks 3 and 4) and O-desmethylvenlafaxine (peaks 5 and 6) formed from the biotransformation of venlafaxine (peaks 1 and 2) in rat liver microsomes

Keywords: Venlafaxine; O-desmethylvenlafaxine; N-desmethylvenlafaxine enantiomers; Liquid-phase microextraction; Biotransformation study; Microsomes

Trace analysis of antidepressants in environmental waters by molecularly imprinted polymer-based solid-phase extraction followed by ultra-performance liquid chromatography coupled to triple quadrupole mass spectrometry by Kristof Demeestere; Mira Petrović; Meritxell Gros; Jo Dewulf; Herman Van Langenhove; Damià Barceló (pp. 825-837).

This paper presents the development, optimization, and validation of an innovative method to analyze trace concentrations of seven selected psychoactive pharmaceuticals in environmental waters. Hereby, the solid-phase extraction (SPE) potential of molecularly imprinted polymers (MIPs) in terms of extraction recovery, breakthrough, precision, and selectivity is studied for the first time. Instrumental analysis by ultra-performance liquid chromatography coupled to triple quadrupole mass spectrometry allowed a rapid (run time = 7.5 min) and sensitive (instrumental detection limit ≤7 pg injected) quantification of the target analytes. A systematic optimization study revealed that, among the seven compounds of interest, mainly the selective serotonin reuptake inhibitors paroxetine, fluoxetine, and citalopram are selectively retained on the MIPs. Experiments performed in spiked river water, sewage treatment plant (STP) effluent and influent showed for these compounds extraction recoveries higher than 70%, breakthrough volumes up to 200 mL, method detection limits (MDL) as low as 0.5 ng/L, and good precision (exemplified by relative standard deviations better than 15%, n ≥ 3). Compared to the widely used hydrophilic–lipophilic balanced (HLB) polymers, the newly developed MIPs indicated to be more resistant toward matrix effects induced ion signal suppression particularly when dealing with relative dirty samples like STP influents. As a result of the better selectivity, the MDL obtained with the MIP-based SPE method was up to a factor of 7 lower compared to those obtained with a recently reported multi-residue HLB method. However, optimizing a HLB method in terms of selectivity, e.g., by introducing a stronger washing protocol, can significantly reduce its MDL up to values approximating those obtained with MIPs.

Keywords: Molecularly imprinted polymers (MIP); Selective serotonin reuptake inhibitors (SSRIs); Benzodiazepines; Extraction; Environmental water analysis

Dynamic non-equilibrium SPME combined with GC, PICI, and ion trap MS for determination of organophosphate esters in air by Johanna Tollbäck; Sindra Isetun; Anders Colmsjö; Ulrika Nilsson (pp. 839-844).

Methodology for time-weighted average (TWA) air measurements of semivolatile organophosphate triesters, widely used flame-retardants and plasticizers, and common indoor pollutants is presented. Dynamic non-equilibrium solid-phase microextraction (SPME) for air sampling, in combination with GC/PICI and ion trap tandem MS, yields a fast, almost solvent-free method with low detection limits. Methanol was used as reagent gas for PICI, yielding stable protonated molecules and few fragments. A field sampler, in which a pumped airflow over three polydimethylsiloxane (PDMS) 100-μm fibers in series was applied, was constructed, evaluated, and used for the measurements. The method LODs were in the range 2–26 ng m⁻³ for a sampling period of 2 h. The uptake on the SPME fibers was shown to be about five times faster for triphenyl phosphate compared to the other investigated organophosphate esters, most likely due to more lipophilic properties of the aromatic compound. The boundary layer for triphenyl phosphate when using a 100-µm PDMS sorbent was determined to 0.08 mm at a linear air velocity of 34 cm s⁻¹. Five different organophosphate triesters were detected in air from a laboratory and a lecture hall, at concentrations ranging from 7 ng m⁻³ up to 2.8 μg m⁻³.

Keywords: Organophosphate triesters; SPME; Non-equilibrium; Dynamic air sampling; PICI; GC/MS/MS

The challenge of analyzing beta-blocker drugs in sludge and wastewater by Marco Scheurer; Maria Ramil; Chris D. Metcalfe; Stefanie Groh; Thomas A. Ternes (pp. 845-856).

In this study, different approaches were used to assess and overcome the severe effects of interference from the sample matrix from different types of sludges and wastewater on the analysis of nine beta-blockers and the beta sympathomimetic clenbuterol. The partitioning of the target compounds into sludge was investigated in wastewater treatment plants (WWTPs) in both Canada and Germany to evaluate whether this is an important mechanism for removal from sewage. Due to ion suppression in the electro spray interface, absolute recoveries were for certain compounds even lower than 20%. By using surrogate standards, acceptable relative recoveries of >75% were achieved for WWTP influents and effluents and for sludges. These matrix effects underline the need to use appropriate surrogate standards to aid in analyte quantitation. Using the developed methods, beta-blockers were detected at concentrations up to 2 μg/L in WWTP effluents, with metoprolol, sotalol, and atenolol present as the dominant compounds. Removal rates within WWTPs were highly inconsistent and ranged from 1-69%. Propranolol showed the greatest degree of partitioning into sludge with solid/water partition coefficients of one order of magnitude higher than those for all other compounds. However, even for propranolol, sorption did not contribute significantly to the overall elimination in WWTPs. It is likely that the removal of beta-blockers during waste water treatment can be attributed primarily to microbial biodegradation.

Keywords: Waste/sludge; Pharmaceuticals; HPLC; Organic compounds/trace organic compounds

The challenge of analyzing beta-blocker drugs in sludge and wastewater by Marco Scheurer; Maria Ramil; Chris D. Metcalfe; Stefanie Groh; Thomas A. Ternes (pp. 845-856).

Keywords: Waste/sludge; Pharmaceuticals; HPLC; Organic compounds/trace organic compounds

A new ozone denuder for aerosol sampling based on an ionic liquid coating by Alexandre Albinet; Nicolas Papaiconomou; Julien Estager; Joël Suptil; Jean-Luc Besombes (pp. 857-864).

A new ionic liquid 1-octyl-3,5-dimethylpyridinium iodide ([O35LUT]⁺[I]⁻) was synthesized and utilized as coating for an ozone denuder device based on a high-volume aerosol sampler (30 m³ h⁻¹). Particle transmission of the denuder was studied, and over 99% of particles ranging from 10 to 2,500 nm were transmitted. The device, containing 4.66 g of ionic liquid, was used outdoors, under dry and damp atmospheric conditions. In order to expose the device to an average concentration of 120 ppbv (240 µg m⁻³) of ozone in air, an additional production of ozone was directly injected into the denuder. Under these conditions, over 97% of ozone was removed for approximately 120 h (5 days). Therefore, iodide-based ionic liquids can be used as a new alternative to conventional denuder coatings in order to reduce artifacts occurring during sampling of particulate matter. Future applications are not limited to ozone removal for specific aerosol sampling methods. Figure Monitoring of HFOD-IL (High Flow Ozone Denuder coated Ionic Liquid) ozone removal efficiency over a long period with different meteorological conditions. Inlet ozone concentration is assumed to be constant between checkpoints.

Keywords: Particle measurement; Sampling artifacts; Ionic liquid; Air pollution

A new ozone denuder for aerosol sampling based on an ionic liquid coating by Alexandre Albinet; Nicolas Papaiconomou; Julien Estager; Joël Suptil; Jean-Luc Besombes (pp. 857-864).

Keywords: Particle measurement; Sampling artifacts; Ionic liquid; Air pollution

A new ozone denuder for aerosol sampling based on an ionic liquid coating by Alexandre Albinet; Nicolas Papaiconomou; Julien Estager; Joël Suptil; Jean-Luc Besombes (pp. 857-864).

Keywords: Particle measurement; Sampling artifacts; Ionic liquid; Air pollution

Development of analytical procedures for trace-level determination of polybrominated diphenyl ethers and tetrabromobisphenol A in river water and sediment by Pierre Labadie; Khawla Tlili; Fabrice Alliot; Catherine Bourges; Annie Desportes; Marc Chevreuil (pp. 865-875).

The aim of this work was to develop procedures for the simultaneous determination of selected brominated flame retardants (BFRs) in river water and in river bed sediment. The target analytes were polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA). To determine dissolved BFRs, a novel mixed-mode solid-phase extraction procedure was developed by combining a hydrophobic sorbent (C₁₈) with a silica-based anion exchange sorbent, so as to overcome the negative artefact induced by dissolved organic carbon. Extraction recoveries exceeded 73% for most analytes, except for BDE-183 and BDE-209 (57%). As regards suspended sediment and river bed sediment, extraction was carried out by means of ultrasonication (recoveries: 73–94%). These procedures, combined to gas chromatography coupled to negative chemical ionisation mass spectrometry (GC-NCI-MS), enabled the determination of BFRs at trace level: 3-160 pg L⁻¹ in river water, 5–145 pg g⁻¹ in bed sediment. These methods were applied to the determination of PBDEs and TBBPA in a suburban river (near Paris, France). PBDEs were systematically detected in the water column (ΣBDEs, 2,300–4,300 pg L⁻¹); they partitioned between the dissolved and particulate phases and BDE-209 was the dominant congener, followed by BDE-99 and BDE-47. TBBPA was detected in the dissolved phase only (<35–68 pg L⁻¹). All selected BFRs were ubiquitous in bed sediments and levels ranged from 3,100 to 15,100 pg g⁻¹ and from 70 to 280 pg g⁻¹ (dry weight), for ΣBDEs and TBBPA, respectively.

Keywords: Polybrominated diphenyl ethers; Tetrabromobisphenol A; Solid-phase extraction; River water; Sediment

GC–MS analysis of low-molecular-weight dicarboxylic acids in atmospheric aerosol: comparison between silylation and esterification derivatization procedures by Maria Chiara Pietrogrande; Dimitri Bacco; Mattia Mercuriali (pp. 877-885).

This paper describes methods for the determination of low-molecular-weight (LMW) dicarboxylic acids in atmospheric aerosols as important chemical tracers for source apportionment of aerosol organics and for studying atmospheric processes leading to secondary organic aerosol formation. The two derivatization procedures most widely used in GC analysis of dicarboxylic acids were compared: esterification using BF₃/alcohol reagent and silylation using N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA). The advantages and drawbacks of the two methods are investigated and compared in terms of (1) precision and accuracy of the results and (2) sensitivity and detection limit of the procedure. The comparative investigation was performed on standard solutions containing target C₃–C₉ dicarboxylic acids and on experimental particulate matter (PM) samples. Attention was focused on low-volume sampling devices that collect small amounts of sample for organic speciation. The results show that, overall, both the techniques appear suitable for the analysis of LMW dicarboxylic acids in atmospheric aerosols since they provide low detection limits (≤4 ng m⁻³) and satisfactory reproducibility (RSD% ≤ 15%). Between them, BSTFA should be the reagent of choice under the most limiting conditions of PM filters collected by low-volume air samplers: It provides determination of all the target C₃–C₉ dicarboxylic acids with lower detection limits (≤2 ng m⁻³) and higher reproducibility (RSD% ≤ 10%) Figure Silylation and esterification derivatization procedures for GC– MS analysis of LMW dicarboxylic acids in atmospheric aerosol.

Keywords: Low-molecular-weight dicarboxylic acids; Derivatization procedures; GC–MS analysis; Atmospheric aerosol; Chemical marker

Phenolic characterization of Northeast Portuguese propolis: usual and unusual compounds by Soraia I. Falcão; Miguel Vilas-Boas; Letícia M. Estevinho; Cristina Barros; Maria R. M. Domingues; Susana M. Cardoso (pp. 887-897).

In this study, an ethanolic extract from Portuguese propolis was prepared, fractionated by high-performance liquid chromatography, and the identification of the phenolic compounds was done by electrospray mass spectrometry in the negative mode. This technical approach allowed the identification of 37 phenolic compounds, which included not only the typical phenolic acids and flavonoids found in propolis from temperate zones but also several compounds in which its occurrence have never been referred to in the literature. Four of the novel phenolic compounds were methylated and/or esterified or hydroxylated derivatives of common poplar flavonoids, although six peculiar derivatives of pinocembrin/pinobanksin, containing a phenylpropanoic acid derivative moiety in their structure, were also identified. Furthermore, the Portuguese propolis sample was shown to contain a p-coumaric ester derivative dimer.

Keywords: Phenolic compounds; Flavonoids; Phenolic acids; Mass spectrometry; Electrospray ionization

Performance evaluation of mapping and linear imaging FTIR microspectroscopy for the characterisation of paint cross sections by Edith Joseph; Silvia Prati; Giorgia Sciutto; Marcella Ioele; Paola Santopadre; Rocco Mazzeo (pp. 899-910).

Different Fourier transform infrared microspectroscopic techniques, using attenuated total reflection (ATR) mode and single-element mercury–cadmium–telluride (MCT) detector (mapping) or multielement MCT detector (raster scanning), are compared with each other for the characterisation of inorganic compounds and organic substances in paint cross sections. All measurements have been performed on paint cross sections embedded in potassium bromide, a transparent salt in the mid-infrared region, in order to better identify the organic materials without the interference of the usual embedding resin. The limitations and advantages of the different techniques are presented in terms of spatial resolution, data quality and chemical information achieved. For all techniques, the chemical information obtained is found to be nearly identical. However, ATR mapping performed with a recently developed instrumentation shows the best results in terms of spectral quality and spatial resolution. In fact, thin organic layers (∼10 µm) have been not only identified but also accurately located. This paper also highlights the recent introduction of multielement detectors, which may represent a good compromise between mapping and imaging systems.

Keywords: Fourier transform infrared (FTIR) microscopy; Attenuated total reflection (ATR); Mapping; Linear imaging; Painting materials

Fast screening immunoassay of sulfonamides in commercial fish samples by Consuelo Cháfer-Pericás; Ángel Maquieira; Rosa Puchades; Javier Miralles; Amelia Moreno (pp. 911-921).

An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed in plate to detect three sulfonamide residues (sulfamerazine (SMR), sulfadimetoxine (SDM), and sulfadiazine (SDZ)) in gilthead sea bream (Sparus aurata) samples. Different extraction methodologies—using methanol/water 1:1 (v/v) + ethylene diamine tetraacetic acid (EDTA) 0.5% (m/v), acetonitrile, phosphate-buffered saline (PBS) 10 mmol L⁻¹ pH 7 and acetate buffer 100 mmol L⁻¹ pH 5—and cleanup steps, based on solid-phase extraction (C₁₈, SCX, Si) or liquid extraction with hexane, were assayed. As optimum, a fast and simple method using acetonitrile was selected to extract the sulfonamide residues from the edible muscle of fish. Due to matrix effects, a standard addition calibration curve in fish extract is necessary for quantification purposes. Sulfonamide-free samples were spiked at different concentration levels (between 30 and 90 ng g⁻¹, 5–15 ng mL⁻¹ in plate) and average recoveries (n = 8), ranging from 71% to 95%, 65% to 79%, and 72% to 95%, were obtained for SMR, SDM, and SDZ, respectively. The assay detection limits for these antibiotics were lower than 100 µg kg⁻¹ (maximum residue level established by the European Union). The accuracy was evaluated by spiking blank fish extracts at different concentrations (10–40 ng mL⁻¹, 5–20 ng mL⁻¹ in plate), and the relative errors ranged between ±20%. Finally, in order to confirm the utility of the developed ELISA as a screening methodology, fish samples from different supermarkets were analyzed, and results were compared with those obtained by a validated high-performance liquid chromatography (HPLC) method. The correlation between the results obtained by both ELISA and HPLC methods is satisfactory. Figure A screening sulfonamide-ELISA method for food security testing in cultured fish.

Keywords: Sulfonamide; ELISA; HPLC; Fish

Fast screening immunoassay of sulfonamides in commercial fish samples by Consuelo Cháfer-Pericás; Ángel Maquieira; Rosa Puchades; Javier Miralles; Amelia Moreno (pp. 911-921).

Keywords: Sulfonamide; ELISA; HPLC; Fish

Optimization of a solid-phase extraction procedure in the fluorimetric determination of sulfonamides in milk using the second-order advantage of PARAFAC and D-optimal design by Rocio Díez Azofra; Luis A. Sarabia; Maria Cruz Ortiz (pp. 923-935).

The objective of this work is to optimize a solid-phase extraction procedure for the simultaneous determination of sulfadiazine, sulfamerazine, and sulfamethazine in milk by fluorimetric detection. For this task, an alternative strategy is employed, which allows one to reduce noticeably the number of experiments without losing the quality of the estimations. It consists of the use of a D-optimal design together with PARAFAC decomposition for the calculation of the response in the experimental design. Effects of amount of cartridge sorbent, kind of milk, volume of conditioning solutions, kind of wash and elution, and kind of mixture of sulfonamides have been evaluated, for maximizing sulfonamide mean recovery and minimizing its standard deviation. Since milk without sulfonamides may give some matrix effect over the fluorescence signal, its behavior has also been studied. Optimal conditions have been selected where the ratio between sulfonamide recovery and milk without sulfonamides was the highest, which are 500 mg of cartridge sorbent, acid wash, and elution and 3 mL of conditioning solutions. The type of milk and mixture of sulfonamides not significant. This makes the procedure suitable for the combined determination of sulfadiazine, sulfamerazine, and sulfamethazine in any kind of milk. Finally, an experimental procedure is proposed, obtaining a sulfonamide mean recovery equal to 68.5% with values of standard deviation between 7 and 8 µg kg⁻¹.

Keywords: Sulfonamides; Fluorescence; Milk; SPE; D-optimal design; PARAFAC

Contribution of microextraction in packed sorbent for the analysis of cotinine in human urine by GC–MS by Florent Lafay; Emmanuelle Vulliet; Marie-Magdeleine Flament-Waton (pp. 937-941).

A simple, rapid, sensitive, and non-consuming solvent method for the determination of cotinine in urine was developed, based on sample preparation by the relatively new technique microextraction in packed sorbent (MEPS) and analysis by GC–MS. This optimized method was compared with conventional solid-phase extraction/liquid–liquid extraction method used as reference. The wide linear range (5–5,000 ng/mL) and high sensitivity of the MEPS method (limit of detection 0.8 ng/mL) allow application to analysis of urine from smokers as well as non-smokers susceptible to passive smoking.

Keywords: Cotinine; Urine; MEPS; GC–MS; Sample preparation

Contribution of microextraction in packed sorbent for the analysis of cotinine in human urine by GC–MS by Florent Lafay; Emmanuelle Vulliet; Marie-Magdeleine Flament-Waton (pp. 937-941).

Keywords: Cotinine; Urine; MEPS; GC–MS; Sample preparation

Small-volume fiber-optic evanescent-wave absorption sensor for nitrite determination by Yan Xiong; Dao-qian Zhu; Chun-feng Duan; Jian-wei Wang; Ya-feng Guan (pp. 943-948).

A novel small-volume fiber-optic evanescent-wave absorption sensor based on the Griess–Ilosvay reaction has been developed and evaluated for nitrite determination. The sensor was constructed by inserting a decladded optical fiber into a transparent capillary to form an annular column microchannel. The Evanescent wave (EW) field produced on the optical fiber core surface penetrated into the surrounding medium and interacted with the azo dye, which was generated by the reaction of nitrite and nitrite-sensitive reagents. The detector was designed to be parallel to the axis of the optical fiber. The defined absorbance was linear with the concentration of nitrite in the range from 0.05 to 10 mg L⁻¹, and the detection limit was 0.02 mg L⁻¹ (3σ) with the relative standard deviation (RSD) of 2.6% (n = 8). The present sensor was successfully used to determine nitrite in real samples of mineral water, tap water, rain water, and seawater. The results were consistent with the data obtained by standard spectrophotometric method, showing potential of the proposed sensor for practical application. Figure Schematic diagram of the evanescent wave in the sensor.

Keywords: Fiber-optic sensor; Nitrite determination; Evanescent wave; Small volume

Small-volume fiber-optic evanescent-wave absorption sensor for nitrite determination by Yan Xiong; Dao-qian Zhu; Chun-feng Duan; Jian-wei Wang; Ya-feng Guan (pp. 943-948).

Keywords: Fiber-optic sensor; Nitrite determination; Evanescent wave; Small volume

Erratum to: Antibiotics in food: Legislation and validation of analytical methodologies by R. Companyó; M. Granados; J. Guiteras; M. D. Prat (pp. 949-949).

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Analytical and Bioanalytical Chemistry (v.396, #2)