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Analytical and Bioanalytical Chemistry (v.394, #3)

Wei Sun wins ABC Best Paper Award by Christina E. Dyllick (pp. 647-648).

Master programs in analytical chemistry by Reiner Salzer (pp. 649-653).

retired as Professor of Analytical Chemistry at the Technische Universität Dresden, Germany, in 2008. He obtained his academic degrees from the University of Leipzig, before taking up his appointment at the TU Dresden. He has authored over 250 books and scientific publications and was elected onto various national and international boards. Professor Salzer is a member of the Norwegian Academy of Science and a recipient of the Emich Plaque of the Austrian Society of Analytical Chemistry. He is a long-time advisory board member for analytical and spectroscopic journals. Professor Salzer served as President of the Division Analytical Chemistry of the German Chemical Society, and is National Delegate to the Division Analytical Chemistry of EuCheMS, where he is Head of the Study Group Education. He was elected as a member of the ECTNA Label Committee for the Chemistry Eurobachelor and Chemistry Euromaster.

European analytical column no. 37 (January 2009) by Bo Karlberg; Manfred Grasserbauer; Jens E. T. Andersen (pp. 655-658).

Analytical methods for molecular gastronomy by Hervé This; Douglas Rutledge (pp. 659-661).

is head of the INRA Molecular Gastronomy Team at the Laboratoire de Chimie Analytique of AgroParisTech, and he is also the Scientific Director of the Foundation Food Science & Culture of the French Academy of Sciences. Co-creator, along with the late Nicholas Kurti, of the scientific discipline called “molecular gastronomy,” he is developing scientific works in his field as well as creating molecular gastronomy groups in various countries around the world. is head of the Laboratoire de Chimie Analytique of AgroParisTech in Paris, France, and director of a combined Institut National de la Research Agronomique/AgroParisTech research unit on Analytical Engineering for Food Quality. He has been working for several years on the development of chemometric tools (PoLiSh, PLS_Cluster, outer product analysis, optimal model dimensionality based on the Durbin–Watson criterion, principal components transform…) for the analysis of instrumental data (time domain NMR, infrared, chromatography).

From differentiating metabolites to biomarkers by Albert Koulman; Geoffrey A. Lane; Scott J. Harrison; Dietrich A. Volmer (pp. 663-670).

The current developments in metabolomics and metabolic profiling technologies have led to the discovery of several new metabolic biomarkers. Finding metabolites present in significantly different levels between sample sets, however, does not necessarily make these metabolites useful biomarkers. The route to valid and applicable biomarkers (biomarker qualification) is long and demands a significant amount of work. In this overview, we critically discuss the current state-of-the-art of metabolic biomarker discovery, with highlights and shortcomings, and suggest a pathway to clinical usefulness.

Keywords: Biomarker discovery; Biomarker validation; Biomarker qualification; Metabolomics; Metabonomics; Metabolic profiling

Trends in Fourier transform infrared spectroscopic imaging by Gerald Steiner; Edmund Koch (pp. 671-678).

Fourier transform infrared (FTIR) spectroscopic imaging is a relatively new method that has received great attention as a new field of analytical chemistry. The greatest benefit of this technique lies in the high molecular sensitivity combined with a spatial resolution down to a few micrometers. Another advantage is the ability to probe samples under native conditions, which allows new insights into samples without the need for fixation, stains, or an additional marker. Advances in instrumentation have made FTIR spectroscopic imaging the tool of choice for an increasing number of applications. The main applications are in the bioanalytical chemistry of cells and tissue, polymers, and recently as well as in homeland security. This report gives a short overview of current developments and recent applications. Figure FTIR image of a polymer blend reveals the chemical composition. Online Abstract Figure (365 KB).

Keywords: Fourier transform infrared imaging spectroscopy; Biomedical applications; Polymer analysis; High-throughput analysis; Analysis of plants

Bioanalytical applications of SERS (surface-enhanced Raman spectroscopy) by Stephen D. Hudson; George Chumanov (pp. 679-686).

Surface-enhanced Raman scattering (SERS) is a powerful technique for analyzing biological samples as it can rapidly and nondestructively provide chemical and, in some cases, structural information about molecules in aqueous environments. In the Raman scattering process, both visible and near-infrared (NIR) wavelengths of light can be used to induce polarization of Raman-active molecules, leading to inelastic light scattering that yields specific molecular vibrational information. The development of surface enhancement has enabled Raman scattering to be an effective tool for qualitative as well as quantitative measurements with high sensitivity and specificity. Recent advances have led to many novel applications of SERS for biological analyses, resulting in new insights for biochemistry and molecular biology, the detection of biological warfare agents, and medical diagnostics for cancer, diabetes, and other diseases. This trend article highlights many of these recent investigations and provides a brief outlook in order to assess possible future directions of SERS as a bioanalytical tool.

Keywords: SERS; Optical labels; Quantitative SERS; Data analysis

Development of bacteria-based bioassays for arsenic detection in natural waters by Elizabeth Diesel; Madeline Schreiber; Jan Roelof van der Meer (pp. 687-693).

Arsenic contamination of natural waters is a worldwide concern, as the drinking water supplies for large populations can have high concentrations of arsenic. Traditional techniques to detect arsenic in natural water samples can be costly and time-consuming; therefore, robust and inexpensive methods to detect arsenic in water are highly desirable. Additionally, methods for detecting arsenic in the field have been greatly sought after. This article focuses on the use of bacteria-based assays as an emerging method that is both robust and inexpensive for the detection of arsenic in groundwater both in the field and in the laboratory. The arsenic detection elements in bacteria-based bioassays are biosensor–reporter strains; genetically modified strains of, e.g., Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Rhodopseudomonas palustris. In response to the presence of arsenic, such bacteria produce a reporter protein, the amount or activity of which is measured in the bioassay. Some of these bacterial biosensor–reporters have been successfully utilized for comparative in-field analyses through the use of simple solution-based assays, but future methods may concentrate on miniaturization using fiberoptics or microfluidics platforms. Additionally, there are other potential emerging bioassays for the detection of arsenic in natural waters including nematodes and clams.

Keywords: Bioassays; Biosensors; Escherichia coli ; Reporter proteins

Capillary electrophoresis and column chromatography in biomedical chiral amino acid analysis by Magdalena C. Waldhier; Michael A. Gruber; Katja Dettmer; Peter J. Oefner (pp. 695-706).

Free amino acids are typically quantified as the sum of their enantiomers, because in terrestrial organisms they mainly exist in the left-handed form. However, with increasing understanding of the biological significance of right-handed amino acids interest in enantioselective quantification of amino acids has steadily increased. Initially, electrophoretic and chromatographic methods using chiral (pseudo)-stationary phases or chiral eluents were applied to the separation of amino acid enantiomers. Later, derivatization of amino acids prior to chromatography with chiral reagents gained in popularity, because the diastereomers formed can be resolved on conventional reversed-phase columns. Novel multi-interaction chiral columns turned attention back to direct chiral chromatographic methods. Hyphenation to mass spectrometry has increasingly replaced optical detection because of superior selectivity, although this has not obviated the need for baseline resolution of amino acid enantiomers. Despite the progress made, enantioselective separation and quantification of amino acids remains an analytical challenge owing to frequently incomplete resolution of all naturally occurring enantiomers and insufficient sensitivity for the determination of the trace amounts of d-amino acids typically found in biological fluids and tissues. Chiral GC-MS analysis of heptafluorobutanol/pentafluoropropionanhydride amino acid derivatives on an Rt-gDEXsa column

Keywords: Amino acid enantiomers; Chiral separation; Capillary electrophoresis; Liquid chromatography; Gas chromatography; Biomedical analysis

Analytical tools for the physicochemical profiling of drug candidates to predict absorption/distribution by Yveline Henchoz; Bruno Bard; Davy Guillarme; Pierre-Alain Carrupt; Jean-Luc Veuthey; Sophie Martel (pp. 707-729).

The measurement of physicochemical properties at an early phase of drug discovery and development is crucial to reduce attrition rates due to poor biopharmaceutical properties. Among these properties, ionization, lipophilicity, solubility and permeability are mandatory to predict the pharmacokinetic behavior of NCEs (new chemical entities). Due to the high number of NCEs, the analytical tools used to measure these properties are automated and progressively adapted to high-throughput technologies. The present review is dedicated to experimental methods applied in the early drug discovery process for the determination of solubility, ionization constants, lipophilicity and permeability of small molecules. The principles and experimental conditions of the different methods are described, and important enhancements in terms of throughput are highlighted. Figure Scheme of the Drug Research Process.

Keywords: Physicochemical profiling; Solubility; Ionization constant; Lipophilicity; Permeability; Experimental models

Current applications and future trends of molecular diagnostics in clinical bacteriology by Jan Weile; Cornelius Knabbe (pp. 731-742).

Molecular diagnostics of infectious diseases, in particular, nucleic-acid-based methods, are the fastest growing field in clinical laboratory diagnostics. These applications are stepwise replacing or complementing culture-based, biochemical, and immunological assays in microbiology laboratories. The first-generation nucleic acid assays were monoparametric such as conventional tests, determining only a single parameter. Improvements and new approaches in technology now open the possibility for the development of multiparameter assays using microarrays, multiplex nucleic acid amplification techniques, or mass spectrometry, while the introduction of closed-tube systems has resulted in rapid microbial diagnostics with a subsequently reduced contamination risk. Whereas the first assays were focused on the detection and identification of microbial pathogens, these new technologies paved the way for the parallel determination of multiple antibiotic resistance determinants or to perform microbial epidemiology and surveillance on a genetic level.

Keywords: Molecular diagnostics; Real-time PCR; Nucleic acid amplification technique; Microarray; Sequencing; Mass spectrometry; Antibiotic resistance

Critical evaluation of sample pretreatment techniques by Tuulia Hyötyläinen (pp. 743-758).

Sample preparation before chromatographic separation is the most time-consuming and error-prone part of the analytical procedure. Therefore, selecting and optimizing an appropriate sample preparation scheme is a key factor in the final success of the analysis, and the judicious choice of an appropriate procedure greatly influences the reliability and accuracy of a given analysis. The main objective of this review is to critically evaluate the applicability, disadvantages, and advantages of various sample preparation techniques. Particular emphasis is placed on extraction techniques suitable for both liquid and solid samples. Figure Miniaturised extraction techniques allow sensitive analysis of also small sample volumes.

Keywords: Sample preparation; Extraction; Fractionation; Critical evaluation

Separation and preconcentration by a cloud point extraction procedure for determination of metals: an overview by C. Bosch Ojeda; F. Sánchez Rojas (pp. 759-782).

Recently, cloud point extraction (CPE) has been an attractive subject as an alternative to liquid–liquid extraction. The technique is based on the property of most non-ionic surfactants in aqueous solutions to form micelles and become turbid when heated to the cloud point temperature. This review covers a selection of the literature published on applications of CPE in determination of metal ions over the period between 2004 and 2008.

Keywords: Cloud point extraction; Metal ions; Preconcentration; Applications; Review

Surface modification using a novel type I hydrophobin HGFI by Sen Hou; Xinxin Li; Xiaoyu Li; Xi-Zeng Feng; Rui Wang; Chen Wang; Lei Yu; Ming-Qiang Qiao (pp. 783-789).

Surface wettability conversion with hydrophobins is important for its applications in biodevices. In this work, the application of a type I hydrophobin HGFI in surface wettability conversion on mica, glass, and poly(dimethylsiloxane) (PDMS) was investigated. X-ray photoelectron spectroscopy (XPS) and water-contact-angle (WCA) measurements indicated that HGFI modification could efficiently change the surface wettability. Data also showed that self-assembled HGFI had better stability than type II hydrophobin HFBI. Protein patterning and the following immunoassay illustrated that surface modification with HGFI should be a feasible strategy for biosensor device fabrication. Figure A hydrophobin HGFI has been applied into surface wettability conversion for protein immobilization

Keywords: Hydrophobin; XPS; WCA; Self-assembly; Protein patterning

Detection of volatile metabolites of Escherichia coli by multi capillary column coupled ion mobility spectrometry by Sasidhar Maddula; Lars Mathias Blank; Andreas Schmid; Jörg Ingo Baumbach (pp. 791-800).

Detection and immediate quantification of microbial metabolic activities is of high interest in fields as diverse as biotechnology and infection biology. Interestingly, the most direct signals of microbial metabolism, the evolution of volatile metabolites, is largely ignored in the literature, and rather, metabolite concentrations in the microbial surrounding or even disruptive methods for intracellular metabolite measurements (i.e., metabolome analysis) are favored. Here, the development of a multi capillary column coupled ion mobility spectrometer (MCC-IMS) was described for the detection of volatile organic compounds from microbes and the MCC-IMS was used for characterization of metabolic activity of growing Escherichia coli. The MCC-IMS chromatogram of the microbial culture off-gas of the acetone-producing E. coli strain BL21 pLB4 revealed four analytes that positively correlated with growth, which were identified as ethanol, propanone (acetone), heptan-2-one, and nonan-2-one. The occurrence of these analytes was cross-validated by solid-phase micro-extraction coupled with gas chromatography mass spectrometry analysis. With this information in hand, the dynamic relationship between the E. coli biomass concentration and the metabolite concentrations in the headspace was measured. The results suggest that the metabolic pathways of heptan-2-one and nonan-2-one synthesis are regulated independent of each other. It is shown that the MCC-IMS in-line off-gas analysis is a simple method for real-time detection of microbial metabolic activity and discussed its potential for application in metabolic engineering, bioprocess control, and health care.

Keywords: Volatile metabolites; MVOC; Escherichia coli ; Acetone; Heptan-2-one; Nonan-2-one; Metabolism; Metabolic network

Separation of malignant human breast cancer epithelial cells from healthy epithelial cells using an advanced dielectrophoresis-activated cell sorter (DACS) by Jaemin An; Jangwon Lee; Sang Ho Lee; Jungyul Park; Byungkyu Kim (pp. 801-809).

In this paper, we successfully separated malignant human breast cancer epithelial cells (MCF 7) from healthy breast cells (MCF 10A) and analyzed the main parameters that influence the separation efficiency with an advanced dielectrophoresis (DEP)-activated cell sorter (DACS). Using the efficient DACS, the malignant cancer cells (MCF 7) were isolated successfully by noninvasive methods from normal cells with similar cell size distributions (MCF 10A), depending on differences between their material properties such as conductivity and permittivity, because our system was able to discern the subtle differences in the properties by generating continuously changed electrical field gradients. In order to evaluate the separation performance without considering size variations, the cells collected from each outlet were divided into size-dependent groups and counted statistically. Following that, the quantitative relative ratio of numbers between MCF 7 and MCF 10A cells in each size-dependent group separated by the DEP were compared according to applied frequencies in the range 48, 51, and 53 MHz with an applied amplitude of 8 V_pp. Finally, under the applied voltage of 48 MHz–8 V_pp and a flow rate of 290 μm/s, MCF 7 and MCF 10A cells were separated with a maximum efficiency of 86.67% and 98.73% respectively. Therefore, our suggested system shows it can be used for detection and separation of cancerous epithelial cells from noncancerous cells in clinical applications.

Keywords: Dielectrophoresis; Cell separation; Microfluidics; Cancer; Malignant cells

HPLC-CHIP coupled to a triple quadrupole mass spectrometer for carbonic anhydrase II quantification in human serum by Luciano Callipo; Patrizia Foglia; Riccardo Gubbiotti; Roberto Samperi; Aldo Laganà (pp. 811-820).

A method for carbonic anhydrase II (CA II) absolute quantification in human serum is presented. This method is based on high-performance liquid chromatography (HPLC)-Chip microfluidic device incorporating a nanoelectrospray source interfaced to a triple quadrupole mass spectrometer. The fraction containing CA II was isolated by preparative reversed-phase HPLC, and peptides obtained from the tryptic digest of the protein mixture were separated by the HPLC-Chip system. The multiple-reaction monitoring acquisition mode of a selected suitable CA II peptide and peptide internal standard allowed the selective and sensitive determination of a CA II. Absolute recovery of the method was 52 ± 12%, while analytical recovery was 81 ± 10%. For the eight samples analyzed, the matrix effect was found to be only −14 ± 6%. A comparison among three regression lines type which were obtained by external calibration, matrix-matched calibration, and standard addition method, respectively, demonstrated that the first one is adequate in obtaining good accuracy and precision. Method quantification limit for CA II in serum was estimated to be 2 fmol/mL. CA II mean concentration in sera from eight healthy subjects was found to be 56 pmol/mL (relative standard deviation 24%).

Keywords: Liquid chromatography-tandem mass spectrometry; Chip; Triple quadrupole; Peptides; Protein absolute quantification

Macrocyclic antibiotics as chiral selectors in the design of enantioselective, potentiometric membrane electrodes for the determination of S-flurbiprofen by Raluca-Ioana Stefan-van Staden; Jacobus F. van Staden; Hassan Y. Aboul-Enein (pp. 821-826).

Construction of three novel enantioselective, potentiometric membrane electrodes based on carbon paste impregnated with different macrocyclic antibiotics vancomycin and teicoplanin as chiral selectors are described. The solutions for the construction of electrodes were prepared in phosphate buffer pH 4 for the vancomycin-based electrode (VCM), pH 6 and pH 6/40% acetonitrile solutions for teicoplanin-based electrodes, TCP I and II, respectively. The proposed electrodes were applied in the assay of S-flurbiprofen raw material and its pharmaceutical formulation by use of direct potentiometry, VCM electrode exhibiting the best enantioselectivity. The surfaces of the electrodes are easily renewable by simply polishing on an alumina paper.

Keywords: Enantioselective; Potentiometric membrane electrode; Enantioselective assay; Vancomycin; Teicoplanin; S-flurbiprofen

Characterization of radix rehmanniae processing procedure using FT-IR spectroscopy through nonnegative independent component analysis by Guoqing Wang; Chunhong Dong; Yukuan Shang; Yu-an Sun; Dexue Fu; Jianbo Zhao (pp. 827-833).

A method is proposed for monitoring the radix rehmanniae proparate processing procedure and determining the endpoint of the process using attenuated total reflectance (ATR) FT-IR through nonnegative independent component analysis (ICA). In the proposed method, ATR FT-IR spectra of the samples were firstly measured at different steaming periods. Then, nonnegative ICA was used for direct estimation of the feature spectra of the pure components in the mixture without pre-separation and other prior information. The estimated independent components (ICs) and their variation of the relative concentrations were used to characterize the processing procedure and determine the endpoint. The results show that the estimated three ICs are consistent with that of the chemical components in the mixtures, i.e. catalpol/rehmaionoside, glucose, and other compounds that nearly keep invariant during the processing procedure. The endpoint determined by the IR-ICA method is 15 h, which was located in the range obtained by expert sensory analysis, whereas the endpoint determined by the traditional sensory analysis is 14 ∼ 17 h and even 14 ∼ 20 h, which showed the significant deviation of the endpoints determined by different operators. Figure Characterisation of radix rehmanniae processing procedure using FT-IR spectroscopy through nonnegative independent component analysis

Keywords: Rehmanniae·processing procedure; ATR FT-IR spectroscopy; Nonnegative independent component analysis; Minimizing mutual information

Sensing method based on impedance variation of minicolumn packed with cation-exchanger under electric field by Tadasuke Tsuji; Shinya Kitagawa; Hajime Ohtani (pp. 835-843).

Voltage-induced impedance variation of the minicolumn (i.d. 0.53 mm, length 2 mm) packed with cation exchanger was investigated to develop a sensing method. An aqueous sample solution containing the metal cations was continuously supplied to the minicolumn during the impedance measurement with the simultaneous application of both alternating current voltage (amplitude, 1.0 V; frequency, 200 kHz to 6 Hz) and direct current (DC) offset voltage (0.1 to 1.0 V). On a complex plane plot, the profile of the column impedance consisted of a semicircle (200 kHz to 100 Hz) and a straight line (<100 Hz), of which slope varied with the magnitude of the applied DC offset voltage (V _DC). The slope–V _DC relation depended on the kind of the metal cation and its concentration; in particular, the slope–V _DC relations of monovalent cations (Na⁺ and K⁺) and divalent ones (Mg²⁺ and Ca²⁺) were significantly different. With the change in the concentration of minor divalent salt of MgCl₂ or CaCl₂ (60 to 140 μM) in the sample solution containing 10 mM NaCl, the slopes showed almost linear relationships between those with application of V _DC = 0.1 V and 1.0 V both for magnesium and calcium additions. In the case of plural addition of both MgCl₂ and CaCl₂ to the solution, the data points in the slope_0.1 _V–slope_1.0 _V plot were located between the two proportional lines for single additions of magnesium and calcium, reflecting both the mixing ratio and net concentrations of the divalent cations. Thus, simulations determination of Mg²⁺ and Ca²⁺ can be attained on the basis of the slope_0.1 _V–slope_1.0 _V relation obtained by the impedance measurements of the minicolumn. Actually, the contents of both magnesium and calcium cations in the bottled mineral waters determined simultaneously using the proposed method were almost equivalent to those obtained by the atomic absorption spectrometric measurement.

Keywords: Chemical sensors; Ion exchange; Impedance variation; DC offset voltage

Development of an automated chemiluminescence flow-through sensor for the determination of 5-aminosalicylic acid in pharmaceuticals: a comparative study between sequential and multicommutated flow techniques by E. J. Llorent-Martínez; P. Ortega-Barrales; M. L. Fernández de Córdova; A. Ruiz-Medina (pp. 845-853).

This work is aimed at demonstrating the potential of the implementation of automatic flow systems in optosensors using chemiluminescence detection. With this purpose, two automatic methodologies, multicommutation and sequential injection analysis (SIA), have been applied to the analysis of 5-aminosalicylic acid (ASA). The analyte is determined for the first time making use of its chemiluminescence reaction with permanganate anion, previously immobilized on an appropriate solid support in the detection area. First, the study of the most appropriate commercial flow-through cell and the optimum conditions for the reaction were performed. Second, the main differences in terms of flow variables and analytical parameters for multicommutation and SIA approaches were stated. Both methodologies were applied to the determination of the analyte in pharmaceuticals obtaining satisfactory results. Finally, the advantages and disadvantages of both proposed methods and the recoveries obtained from pharmaceuticals were statistically compared.

Keywords: Automation; Multicommutation; SIA; Mesalazine; Chemiluminescence

Disposable DNA biosensor with the carbon nanotubes–polyethyleneimine interface at a screen-printed carbon electrode for tests of DNA layer damage by quinazolines by Júlia Galandová; Renáta Ovádeková; Adriana Ferancová; Ján Labuda (pp. 855-861).

A screen-printed carbon working electrode within a commercially available screen-printed three-electrode assembly was modified by using a composite of multiwalled carbon nanotubes (MWCNT) dispersed in polyethylenimine (PEI) followed by covering with the calf thymus dsDNA layer. Several electrochemical methods were used to characterize the biosensor and to evaluate damage to the surface-attached DNA: square wave voltammetry of the [Ru(bpy)₃]²⁺ redox indicator and mediator of the guanine moiety oxidation, cyclic voltammetry and electrochemical impedance spectroscopy in the presence of the [Fe(CN)₆]^3−/4− indicator in solution. Due to high electroconductivity and large surface area of MWCNT and positive charge of PEI, the MWCNT–PEI composite is an advantageous platform for the DNA immobilization by the polyelectrolyte complexation and its voltammetric and impedimetric detection. In this respect, the MWCNT–PEI interface exhibited better properties than the MWCNT–chitosan one reported from our laboratory previously. A deep DNA layer damage at incubation of the biosensor in quinazoline solution was found, which depends on the quinazoline concentration and incubation time. Figure Impedance spectra for the modified electrodes. Conditions: 1 mM [Fe(CN)₆]^3–/4– in 0.1 M PBS (pH = 7.0), potential amplitude 10 m V, frequency range 12–1×10₄ Hz.

Keywords: Screen-printed carbon electrode; DNA biosensor; Carbon nanotubes; Polyethylenimine; Quinazoline

A semi-quantitative dipstick assay for microcystin by Nils Tippkötter; Henning Stückmann; Stephen Kroll; Gunda Winkelmann; Udo Noack; Thomas Scheper; Roland Ulber (pp. 863-869).

An immunochromatographic lateral flow dipstick assay for the fast detection of microcystin-LR was developed. Colloid gold particles with diameters of 40 nm were used as red-colored antibody labels for the visual detection of the antigen. The new dipstick sensor is capable of detecting down to 5 µg·l⁻¹ (ppb; total inversion of the color signal) or 1 ppb (observation of color grading) of microcystin-LR. The course of the labeling reaction was observed via spectrometric wave shifts caused by the change of particle size during the binding of antibodies. Different stabilizing reagents showed that especially bovine serum albumin (BSA) and casein increase the assays sensitivity and the conjugate stability. Performance of the dipsticks was quantified by pattern processing of capture zone CCD images. Storage stability of dipsticks and conjugate suspensions over 115 days under different conditions were monitored. The ready-to-use dipsticks were successfully tested with microcystin-LR-spiked samples of outdoor drinking- and salt water and applied to the tissue of microcystin-fed mussels.

Keywords: Dipstick; Immunochromatographic; Toxin; Microcystin; Gold nanoparticles; Lateral flow

Phytochemical analysis of young fustic (Cotinus coggygria heartwood) and identification of isolated colourants in historical textiles by Lemonia Valianou; Konstantina Stathopoulou; Ioannis Karapanagiotis; Prokopios Magiatis; Eleni Pavlidou; Alexios-Leandros Skaltsounis; Yannis Chryssoulakis (pp. 871-882).

Young fustic (Cotinus coggygria Scop.; Anacardiaceae) has been used as a dyestuff since antiquity. Phytochemical investigation of the methanol extract of the heartwood has led to the isolation and structure elucidation by nuclear magnetic resonance and mass spectrometry (MS) of 3′,4′,6-trihydroxyaurone (sulfuretin) and 3′,4′,7-trihydroxyflavonol (fisetin) as well as 3′,4′,7-trihydroxyflavanol (fustin), 3′,4′,5,7-tetrahydroxyflavonol (quercetin), 3′,4′,5,7-tetrahydroxyflavanol (taxifolin), 4′,7-dihydroxyflavanol, 3′,4′,7-trihydroxyflavanone (butin), 4′,7-dihydroxyflavanone (liquiritigenin), trans-2′,3,4,4′-tetrahydroxychalcone (butein), 4′,5,7-trihydroxyflavanone and trans-2′,4,4′-trihydroxychalcone (isoliquiritigenin). The isolated compounds were used as reference materials for the development of a high-performance liquid chromatography–diode array detector–MS method, which was then applied to analyse (1) fresh silk samples dyed with young fustic, (2) dyed silk subjected to artificially accelerated light ageing and (3) historical silk micro-samples, extracted from ecclesiastical post-Byzantine garments (fifteenth to eighteenth century), which belong to monasteries of Mount Athos. Sulfuretin and fisetin, which are usually used as markers for the identification of the yellow dye and, for the first time, some of the aforementioned flavonoid components of young fustic were identified in the historical extracts. Furthermore, preliminary experiments suggested that although the amounts of the dye components decrease with light ageing, the relative ratio of fisetin and sulfuretin, after a first step of ageing, seems to be almost unaffected by such degradation processes raised by light. The effect of the latter on the morphology of the dyed silk fibres is briefly investigated by scanning electron microscopy.

Keywords: HPLC; Natural products; NMR/ESR; Archeometry/fine arts

Determination of 2-ethylhexyl 4-(dimethylamino) benzoate using membrane-assisted liquid–liquid extraction and gas chromatography-mass spectrometric detection by J. G. March; C. Genestar; B. M. Simonet (pp. 883-891).

A flow-cell for micro-porous membrane liquid–liquid extraction with a sheet membrane was used to extract 2-ethylhexyl 4-(dimethylamino) benzoate (EDB) from urine of solar-cream users and spiked wine samples. The cell enabled the target analyte to be extracted from 7.9 mL of donor solution into 200 μL of acceptor solution (decane). After extraction, the acceptor solution was transferred to a micro-vial for GC-MS analysis without derivation. In this work, variables affecting the enrichment factor were also studied, such as organic solvent, extraction time, recirculation flow of the donor solution through the donor chamber, presence of potassium chloride and ethanol in the donor solution and pH. The method has been evaluated in terms of linearity, sensitivity, precision, limits of detection and quantification and extraction efficiency. Limits of quantification were 1 and 3 μg L⁻¹ EDB for urine and wine, respectively. Quantitative analysis has been carried out by applying the method of standard additions. Within- and between-day relative standard deviations were lower than 12% and 20%, respectively. EDB was found in the urine of users of cream containing EDB in the concentration interval 1.2–7.2 μg L⁻¹. Therefore, this provides evidence of EDB dermal absorption and subsequent excretion through the urinary tract. EDB was not found in the analysed wine samples.

Keywords: 2-Ethylhexyl 4-(dimethylamino) benzoate; Micro-porous membrane liquid–liquid extraction; Urine; Wine; Gas chromatography-mass spectrometry

Solid-phase micro-extraction procedure for the determination of 1,3-dichloro-2-propanol in water by on-fibre derivatisation with bis(trimethylsilyl)trifluoroacetamide by Antonia María Carro; Paula González; Noelia Fajar; Rosa Antonia Lorenzo; Rafael Cela (pp. 893-901).

The headspace solid-phase micro-extraction technique with on-fibre derivatisation followed by gas chromatography-tandem mass spectrometry has been evaluated for the analysis of 1,3-dichloro-2-propanol in water. An asymmetric factorial design has been performed to study the influence of five experimental factors: extraction time and temperature, derivatisation time and temperature and pH. The best extraction performance is achieved in the headspace mode, with 5 mL stirred water samples (pH 4) containing 1.3 g of NaCl, equilibrated for 30 min at 25 °C, using divinylbenzene-carboxen-polydimethylsiloxane as the fibre coating. On-fibre derivatisation has been used for the first time with 50 µL of bis(trimethylsilyl)trifluoroacetamide at 25 °C during 15 min, leading to effective yields. The proposed method provides high sensitivity, good linearity and repeatability (relative standard deviation of 5.1% for 10 ng mL⁻¹ and n = 5). The limits of detection and quantification were 0.4 and 1.4 ng mL⁻¹, respectively. Analytical recoveries obtained for different water samples were approx. 100%.

Keywords: 1,3-Dichloro-2-propanol; HS-SPME; On-fibre derivatisation; GC-MS/MS; Water

Adaptation of the ORAC assay to the common laboratory equipment and subsequent application to antioxidant plastic films by K. Bentayeb; P. Vera; C. Rubio; C. Nerin (pp. 903-910).

The oxygen radical absorbance capacity (ORAC) method has been adapted to the instrumental laboratory and optimized for the determination of the antioxidant capacity of a novel active packaging. As the ORAC assay requires the monitorization of a reaction at controlled temperature by means of the fluorescence signal decrease over time, specific instrumental is usually necessary. In this work, a common liquid chromatographic device has been adapted to perform the ORAC assay, leaving it accessible to any laboratory. Using this adaptation, five different essential oils have been determined resulting in the following antioxidant order: clove (2.66 g Trolox per gram of essential oil), oregano (2.25), cinnamon (1.93), rosemary (1.66), and ginger (1.47). After incorporating the essential oils to the film, its antioxidant capacity has also been checked and related to the concentration of essential oil as well as the thickness of the active film. The results point out that for the same amount of essential oil incorporated measured as grams per square meter, thicker films have more antioxidant capacity than the thinner and more concentrated ones. Furthermore, the antioxidant capacity found in the films was always higher than expected taking into account the amount of essential oil incorporated. Some likely explanations have been proposed, leading to the improvement of the antioxidant film under development.

Keywords: ORAC; Antioxidant film; Essential oil; Active packaging

Synchrotron X-ray 2D and 3D elemental imaging of CdSe/ZnS quantum dot nanoparticles in Daphnia magna by Brian P. Jackson; Heather E. Pace; Antonio Lanzirotti; Randy Smith; James F. Ranville (pp. 911-917).

The potential toxicity of nanoparticles to aquatic organisms is of interest given that increased commercialization will inevitably lead to some instances of inadvertent environmental exposures. Cadmium selenide quantum dots (QDs) capped with zinc sulfide are used in the semiconductor industry and in cellular imaging. Their small size (<10 nm) suggests that they may be readily assimilated by exposed organisms. We exposed Daphnia magna to both red and green QDs and used synchrotron X-ray fluorescence to study the distribution of Zn and Se in the organism over a time period of 36 h. The QDs appeared to be confined to the gut, and there was no evidence of further assimilation into the organism. Zinc and Se fluorescence signals were highly correlated, suggesting that the QDs had not dissolved to any extent. There was no apparent difference between red or green QDs, i.e., there was no effect of QD size. 3D tomography confirmed that the QDs were exclusively in the gut area of the organism. It is possible that the QDs aggregated and were therefore too large to cross the gut wall.

Keywords: Nanoparticles; Quantum dots; Synchrotron XRF; Elemental imaging; Tomography

A fiber-optic evanescent wave sensor for dissolved oxygen detection based on novel hybrid fluorinated xerogels immobilized with [Ru(bpy)₃]²⁺ by Yan Xiong; Jing Xu; Jian-Wei Wang; Ya-Feng Guan (pp. 919-923).

We have prepared a novel fiber-optic evanescent wave sensor (FEWS) for dissolved oxygen (DO) detection. The sensor fabrication was based on coating a decladded portion of an optical fiber with a microporous coating, which was prepared from 3,3,3-trifluoropropyltrimethoxysilane and n-propyltrimethoxysilane. The fluorophores were immobilized in the porous coating and excited by the evanescent wave field produced on the core surface of the optical fiber. The sensitivity of the sensor was quantified by the ratio of the fluorescence intensities in pure deoxygenated (I ₀) and in pure oxygenated environments (I). Results show that the quenching response of DO is increased with the enhancement of the coating surface hydrophobicity using the presented hybrid fluorinated ORMOSILs. The calibration curve of I ₀/I to [O₂] is linear from 0 to 40 ppm and the detection limit is 0.05 ppm (3σ) with a short response time of 15 s for DO detection. Figure

Keywords: Fiber-optic; Evanescent wave sensor; Dissolved oxygen; Hybrid ORMOSILs materials; [Ru(bpy)₃]²⁺

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Analytical and Bioanalytical Chemistry (v.394, #3)

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Analytical and Bioanalytical Chemistry (v.394, #3)