Check out our New Publishers' Select for Free Articles

Analytical and Bioanalytical Chemistry (v.391, #4)

Euroanalysis XIV The European Conference on Analytical Chemistry by Koen Janssens; Piet Van Espen; Luc Van’t Dack (pp. 1107-1108).

European analytical column No. 36 (January 2008) by Bo Karlberg; Hendrik Emons; Jens E. T. Andersen (pp. 1109-1112).

Some aspects of the rise of analytical chemistry in Belgium by D. Thorburn Burns; Hendrik Deelstra (pp. 1113-1117).

is professor emeritus of analytical chemistry in the Queen’s University of Belfast. His current research areas are instrumental methods, data evaluations for legal and forensic purposes and the development and history of analytical chemistry from the XVI to the XIX centuries. is professor emeritus of the University of Antwerp, where he taught food chemistry and environmental chemistry to pharmacists and spectrometric methods to chemists. Since becoming emeritus he researches on the history of chemistry and pharmacy in Belgium, focusing on the XIX and XX centuries.

Determination of anticarcinogenic and rescue therapy drugs in urine by photoinduced spectrofluorimetry using multivariate calibration: comparison of several second-order methods by M. I. Rodríguez Cáceres; I. Durán Merás; N. E. Ornelas Soto; P. L. López de Alba; L. López Martinez (pp. 1119-1127).

This paper shows the potential of excitation–emission fluorescence spectroscopy and several second-order methods, such as parallel factor analysis (PARAFAC), multiway partial least-squares (N-PLS) or bilinear least-squares (BLLS), as a multicalibration technique for the analysis of leucovorin (LV) and irinotecan (CPT-11). Although CPT-11 presents native fluorescence, leucovorin has little native fluorescence; however, under irradiation with short-wavelength UV light in the presence of traces of hydrogen peroxide, leucovorin was converted into a highly fluorescent compound. This reaction has been used for the sensitive and selective determination of both compounds. The convenience of analysing the total luminescence spectrum information when using multivariate calibration methods on fluorescence data is demonstrated. Direct determination of mixtures of both drugs in urine was accomplished on the basis of excitation–emission matrices (EEMs) and the three-way multivariate methods.

Keywords: Irinotecan; Leucovorin; Photoinduced fluorescence; Multivariate calibration; N-PLS/RBL; PARAFAC; BLLS

Advantages of combined μ-XRF and μ-XRD for phase characterization of Ti–B–C ceramics compared with conventional X-ray diffraction by Jakub Jaroszewicz; Wout De Nolf; Koen Janssens; Andrzej Michalski; Gerald Falkenberg (pp. 1129-1133).

Design and processing of new materials with improved high-temperature properties is one of the most challenging tasks of modern engineering. Among such materials, nonoxidic ceramics hold an important place. When optimizing the synthesis conditions of these new materials in an largely empirical manner, the use of analytical methods that can fully document the resulting phase compositions is of great importance. In this paper, we demonstrate the advantages of using combined microbeam X-ray diffraction and X-ray fluorescence over conventional X-ray diffraction as the characterization method in the specific case of Ti–B–C ceramics. Ceramic samples were synthesized by the pulse plasma method starting from high-purity powders of titanium, boron, graphite, and nickel. Different mixtures were heated in a pulsed fashion and sintered by combustion synthesis at various temperatures and time durations, as is the case during empirical optimization of a synthesis procedure. Conventional X-ray diffraction showed the presence of two phases at the end of the sintering process, TiB₂ and TiC, irrespective of the conditions employed. Scanning μ-XRF/μ-XRD on the other hand allowed one to detect and visualize the distribution of additional phases present in the sintering products, during which a dependence on sintering conditions was apparent. The μ-XRD results showed that three phases (TiB₂, TiC, and TiB) instead of two were present in samples sintered during a short time interval. The addition of metallic Ni to the initial mixture as a sintering facilitator resulted in the formation of a Ni₃B phase. All phases proved to have strongly heterogeneous distributions above the 15-μm level with the presence of TiB₂ anticorrelated to that of TiC and TiB, emphasizing the necessity of the use of laterally resolved methods of characterization.

Keywords: X-ray diffraction (XRD); X-ray fluorescence (XRF); Synchrotron radiation; Ceramics; Pulse plasma sintering; Boron; Titanium

Feasibility of using solid sampling graphite furnace atomic absorption spectrometry for preparation of spiked filter papers with Cu and Zn as standards for direct solid analysis by Cassiana S. Nomura; Danielle P. Intima; Pedro V. Oliveira; Iolanda A. Ruffini; Francisco J. Krug (pp. 1135-1137).

An approach was developed for the preparation of cryogenic ground spiked filter papers with Cu and Zn for use as synthetic calibrating standards for direct solid microanalysis. Solid sampling graphite furnace atomic absorption spectrometry was used to evaluate the microhomogeneity and to check the applicability of the synthetic calibrating standards for the direct determination of Cu and Zn in vegetable certified reference materials. The found concentrations presented no statistical differences at the 95% confidence level. The homogeneity factors ranged from 2.7 to 4.2 for Cu and from 6.4 to 11.5 for Zn.

Keywords: Solid sampling; Graphite furnace; Calibrating standard; Microhomogeneity

Combined use of carbon nanotubes and ionic liquid to improve the determination of antidepressants in urine samples by liquid chromatography by Marta Cruz-Vera; Rafael Lucena; Soledad Cárdenas; Miguel Valcárcel (pp. 1139-1145).

Antidepressants are widely used for the treatment of psychiatric disorders and therefore their monitoring in biological fluids is quite important taking into account that they can produce dangerous biochemical imbalances in toxic doses. A method for the determination of antidepressants in urine samples is presented using solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Home-made cartridges containing 30 mg multiwall carbon nanotubes are employed for isolation of the analytes from the sample, allowing also the preconcentration of the analytes prior to the HPLC analysis. Chromatographic separation was achieved in a reversed-phase C₈ column using the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate as silanol activity suppressor, which enhances peak symmetry and chromatographic resolution. Limits of detection were 12.3 ng mL⁻¹ for trazodone and 90.1 ng mL⁻¹ for fluoxetine. The repeatability of the proposed method expressed as RSD (n = 11) varied between 3.4% (fluoxetine) and 5.0% (desipramine and mianserine). Thus, the method is suitable for the therapeutic monitoring of antidepressants in urine samples.

Keywords: Multiwalled carbon nanotubes; Ionic liquid; Solid-phase extraction; Liquid chromatography; Antidepressants; Urine samples

Immunomagnetic separation using carbonyl iron powder and flow cytometry for rapid detection of Flavobacterium psychrophilum by Kyoko Hibi; Hideki Ushio; Hideo Fukuda; Kohji Mitsubayashi; Tetsuhito Hayashi; Huifeng Ren; Hideaki Endo (pp. 1147-1152).

Bacterial cold water disease, caused by Flavobacterium psychrophilum, is a serious problem in the aquaculture industry worldwide. Several methods to prevent and treat cold water disease have been studied. Although detection at the early stage of F. psychrophilum infection is very important for the prevention and treatment of cold water disease, an effective detection method has not yet been developed. The use of flow cytometry (FCM) for the rapid determination of bacterial cell numbers with high sensitivity is beginning to attract attention. Immunomagnetic separation (IMS) has also been used to detect F. psychrophilum. The purpose of the present study was to develop a method to quickly determine the number of bacterial cells by combining the FCM and IMS methods. Because samples can be more effectively concentrated using smaller magnetic beads and stronger magnetism, we used carbonyl iron powder as the magnetic beads for the IMS. The detection level of F. psychrophilum using FCM combined with IMS was 5 orders lower than that using FCM without IMS. The values determined using FCM combined with IMS strongly correlated with those obtained using the colony-counting method, in the range of approximately 10–10⁸ colony-forming units per milliliter. One FCM assay could be completed within 60 s and the total assay time, including sample preparation, was less than 2 h. The combined method of FCM with IMS developed in this study can be used reliably for the rapid detection of F. psychrophilum.

Keywords: Bacteria; Immunomagnetic separation; Magnet beads; Carbonyl iron powder; Flow cytometry; Bacterial cold water disease

The use of plasmatic acceptors as specific ligands in affinity chromatography cleanup of veterinary drugs from biological matrices by Pasquale Gallo; Antonella Nasi; Floriana Vinci; Maurizio Fiori; Gianfranco Brambilla; Luigi Serpe (pp. 1153-1162).

Bovine α₁-acid glycoprotein (bAAG) and bovine serum albumin (BSA) are plasmatic acceptors working as carriers by the specific and reversible binding of several drugs in vivo. We synthesized affinity columns by coupling bAAG and BSA to an activated chromatographic support through their carbohydrate moieties, to preserve protein tertiary structure and, consequently, to improve the biological activity in vitro. The bAAG and BSA affinity columns were used to study the binding of acidic and basic drugs. Moreover, a purification strategy was developed for the cleanup of drug residues from biological matrices and foods, prior to screening and/or confirmatory analysis, on the basis of the specific molecular recognition between the protein and the drug. The aim of this work was to test the potency of bAAG- and BSA-based affinity chromatography to bind some veterinary drugs and purify them in the context of the official control of animal products. The efficiency of these homemade affinity columns in minimising matrix interference and in selective cleanup of different classes of substances was reported and discussed. Figure “Coupling strategies in synthesizing plasmatic acceptor affinity columns: the covalent coupling of bAAG and BSA through their carbohydrate moiety allows one to preserve the gross tertiary structure of the protein and thus its biological activity, whereas coupling through the ε-amine group of lysine residues can reduce the interactions with the binding sites of the plasmatic acceptor.”

Keywords: Affinity chromatography; Basic drugs; Acid drugs; Bovine α₁-acid glycoprotein; Bovine serum albumin

A new method of comparing 2D-PAGE maps based on the computation of Zernike moments and multivariate statistical tools by Emilio Marengo; Elisa Robotti; Marco Bobba; Marco Demartini; Pier Giorgio Righetti (pp. 1163-1173).

The aim of this work was to obtain the correct classification of a set of two-dimensional polyacrylamide gel electrophoresis map images using the Zernike moments as discriminant variables. For each 2D-PAGE image, the Zernike moments were computed up to a maximum p order of 100. Partial least squares discriminant analysis with variable selection, based on a backward elimination algorithm, was applied to the moments calculated in order to select those that provided the lowest error in cross-validation. The new method was tested on four datasets: (1) samples belonging to neuroblastoma; (2) samples of human lymphoma; (3) samples from pancreatic cancer cells (two cell lines of control and drug-treated cancer cells); (4) samples from colon cancer cells (total lysates and nuclei treated or untreated with a histone deacetylase inhibitor). The results demonstrate that the Zernike moments can be successfully applied for fast classification purposes. The final aim is to build models that can be used to achieve rapid diagnosis of these illnesses.

Keywords: Zernike moments; Partial least squares discriminant analysis; 2D-PAGE maps; Classification; Multivariate analysis

Simultaneous determination of bisphenol A, triclosan, and tetrabromobisphenol A in human serum using solid-phase extraction and gas chromatography-electron capture negative-ionization mass spectrometry by Alin C. Dirtu; Laurence Roosens; Tinne Geens; Adriana Gheorghe; Hugo Neels; Adrian Covaci (pp. 1175-1181).

This study aimed at optimizing and validating a sensitive method for simultaneous determination of bisphenol A (BPA), triclosan (TCS), and tetrabromobisphenol A (TBBPA) in human serum using solid-phase extraction (SPE) and gas chromatography coupled to electron-capture negative-ionization mass spectrometry (GC-ECNI/MS). Sample preparation involved denaturation of serum proteins with formic acid followed by SPE on an Oasis HLB cartridge. Fractionation was performed on Florisil from which the phenolic compounds were eluted with methanol-dichloromethane (DCM) (5:1, v/v). The phenolic fraction was further derivatized with pentafluoropropionic acid anhydride (30 min at 70°C). Further liquid-liquid partitioning using hexane-DCM (4:1, v/v) and K₂CO₃ 3% aqueous solution was used to eliminate excess reagent and acidic by-products formed during derivatization. The cleaned extract was injected into a GC-ECNI/MS system operated in selected ion monitoring mode. For thorough method validation, each step of the procedure was rigorously optimized. The method limits of quantitation for BPA, TCS, and TBBPA were 0.28 ng mL⁻¹, 0.09 ng mL⁻¹ and 0.05 ng mL⁻¹, respectively. Furthermore, the method was applied to 21 Belgian human serum samples. The median concentrations obtained for BPA (0.71 ng mL⁻¹) and TCS (0.52 ng mL⁻¹) in Belgian human serum samples were similar to previously reported data for human fluids. Slightly higher levels of TBBPA (0.08 ng mL⁻¹) were found in Belgium samples compared to Norwegian serum. Figure Phenolic endocrine disruptors, such as bisphenol A, triclosan and tetrabromobisphenol A, are preferentially measured in human serum at low ng/mL range.

Keywords: Bisphenol A; Triclosan; Tetrabromobisphenol A; Solid-phase extraction; Gas chromatography-mass spectrometry; Human serum

Interference of chitosan in glucose analysis by high-performance liquid chromatography with evaporative light scattering detection by B. N. Estevinho; A. Ferraz; F. Rocha; A. Alves; L. Santos (pp. 1183-1188).

The purpose of this work was to quantify glucose in aqueous solutions containing chitosan by high-performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD). Chitosan is a natural compound that is used alone or as an additive in several formulations. Microencapsulation of bioactive compounds such as glucose, by means of chitosan, is being explored, but difficulties arise when glucose needs to be determined in the presence of chitosan. HPLC is the technique most commonly used for glucose analysis, and ELSD may offer advantages (e.g. sensitivty and the possibility of operating in gradient mode) compared with other detectors. The influence of chitosan in the analysis of glucose by HPLC with ELSD was investigated at different pH values of the aqueous solutions. Isocratic elution with an acetonitrile/water mixture (80:20, v/v) and water washing between runs were the best options to avoid the mucoadhesive properties of chitosan, which are responsible for column degradation and variability of the retention time of glucose. The developed methodology was considered completely adequate for rapid glucose analysis in aqueous solutions with low pH (< 3), in the presence of chitosan. Figure Chitosan

Keywords: Glucose; Chitosan; HPLC; Evaporative light scattering detection (ELSD)

A new liquid chromatographic method for routine determination of oxytetracycline marker residue in the edible tissues of farm animals by Dimitrios J. Fletouris; Elias P. Papapanagiotou (pp. 1189-1198).

A simple, rapid, and specific ion-pair liquid chromatographic method for routine determination of the marker residue of oxytetracycline (OTC), namely OTC and 4-epi-oxytetracycline (4-epiOTC), in edible animal tissues (muscle, liver, kidney, and fat) has been developed. Minced tissue samples were acidified at pH 2.7 with 2 mol L⁻¹ sulfuric acid and extracted with acetonitrile. The extracts were purified by treatment with ammonium sulfate solution and concentrated into 0.1 mol L⁻¹ phosphoric acid. Baseline separation was carried out isocratically on a Nucleosil 100-5 C₁₈, 5-μm column using an acetonitrile–0.01 mol L⁻¹ disodium hydrogen phosphate (20:80, v/v) mobile phase that contained both positively (tetrabutylammonium) and negatively (octanesulfonate) charged pairing ions and EDTA, and was adjusted to pH 3.8. Detection was by UV at 370 nm. The method was fully validated according to Commission Decision 2002/657/EC. Overall recoveries were better than 82.6% and overall relative standard deviation was better than 6% for all the tissues examined. The good analytical characteristics of the method allowed limits of quantification as low as 30 ng g⁻¹ for muscle and fat and 50 ng g⁻¹ for liver and kidney, for both OTC and 4-epiOTC, to be realized. The method was successfully used to determine the OTC marker residue in tissues of two sheep intramuscularly administered a commercial OTC formulation.

Keywords: Oxytetracycline; 4-epi-Oxytetracycline; Residues; Animal tissues; Ion-pair liquid chromatography

Development and in-house validation of an LC-MS/MS method for the determination of stilbenes and resorcylic acid lactones in bovine urine by Kathrin Schmidt; Carolin Stachel; Petra Gowik (pp. 1199-1210).

Stilbenes and zeranol are nonsteroidal estrogenic growth promoters which are banned in the European Union (EU) for use in food-producing animals by Council Directive 96/22/EC. A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed for the screening and confirmation of stilbenes (diethylstilbestrol, dienestrol, hexestrol) and resorcylic acid lactones (zeranol and its metabolites taleranol and zearalanone as well as the mycotoxins α-zearalenol, β-zearalenol and zearalenone) in bovine urine. The method permits the confirmation and quantification of stilbenes and resorcylic acid lactones at levels below 1 µg L⁻¹ and 1.5 µg L⁻¹, respectively. The validation was carried out according to Commission Decision 2002/657/EC, Chap. 3.1.3 “alternative validation” by a matrix-comprehensive in-house validation concept. Decision limit CCα, detection capability CCβ, recovery, repeatabiliy, within-laboratory reproducibility and the uncertainty of measurement were calculated. Furthermore, a factorial effect analysis was carried out to identify factors that have a significant influence on the method. Factors considered to be relevant for the method in routine analysis (e.g. operator, matrix condition, storage duration of the extracts before measurement, different cartridge lots, hydrolysis conditions) were systematically varied on two levels. The factorial analysis showed that different cartridge lots, storage durations and matrix conditions can exert a relevant influence on the method.

Keywords: Zeranol; Stilbenes; Matrix-comprehensive in-house validation; Bovine urine; LC-MS/MS; Factorial analysis; Measurement uncertainty; Residue control

A new ICP–TOFMS. Measurement and readout of mass spectra with 30 μs time resolution, applied to in-torch LA–ICP–MS by Martin Tanner; Detlef Günther (pp. 1211-1220).

In-torch LA–ICP–MS was implemented into an in-house-built ICP–TOFMS system. The fast data acquisition capabilities of the new configuration allowed simultaneous multi-element measurement and readout of in-torch LA–ICP–MS signals with 30 μs time resolution. The measurements confirmed previously observed fine structures of in-torch generated signals and provided new insights in the dynamic processes in the plasma on a microsecond time scale. The new setup is described in detail and first figures of merit are given. Figure Time dependent multi element signal after laser ablation in the torch of an ICP-TOFMS instrument

Keywords: In-torch; Laser ablation; ICP–TOFMS; Brass; Microsecond resolution

Structure analysis using acoustically levitated droplets by J. Leiterer; F. Delißen; F. Emmerling; A. F. Thünemann; U. Panne (pp. 1221-1228).

Synchrotron diffraction with a micrometer-sized X-ray beam permits the efficient characterization of micrometer-sized samples, even in time-resolved experiments, which is important because often the amount of sample available is small and/or the sample is expensive. In this context, we will present acoustic levitation as a useful sample handling method for small solid and liquid samples, which are suspended in a gaseous environment (air) by means of a stationary ultrasonic field. A study of agglomeration and crystallization processes in situ was performed by continuously increasing the concentration of the samples by evaporating the solvent. Absorption and contamination processes on the sample container walls were suppressed strongly by this procedure, and parasitic scattering such as that observed when using glass capillaries was also absent. The samples investigated were either dissolved or dispersed in water droplets with diameters in the range of 1 micrometer to 2 millimeters. Initial results from time-resolved synchrotron small- and wide-angle X-ray scattering measurements of ascorbic acid, acetylsalicylic acid, apoferritin, and colloidal gold are presented.

Keywords: X-ray diffraction methods; SAXS; WAXS; Nanoparticles; Nanotechnology; Sampling; Acoustic levitation; Agglomeration; Crystallization

The use of FTIR and NMR spectroscopies to study prepolymerisation interactions in nitrogen heterocycles by Qendresa Osmani; Helen Hughes; Kevin Flavin; Jimmy Hedin-Dahlstrom; Christopher J. Allender; June Frisby; Peter McLoughlin (pp. 1229-1236).

A detailed investigation into the functional groups responsible for the formation of a noncovalent complex between 2-aminopyridine (template) and methacrylic acid (functional monomer) has been carried out using FTIR spectroscopy and confirmed by ¹H NMR spectroscopic data. The approach adopted to confirm the mechanism of interaction was the analysis of the template plus the structurally similar 2-methylaminopyridine and 2-dimethylaminopyridine. A 1:1 stoichiometry of complexation was determined by Job plot analysis following titration, with FTIR results complementing those of the ¹H NMR study. The strength of interaction between 2-aminopyridine and the functional monomer measured through band shifts by FTIR spectroscopy was compared with such interactions for the isomers 3- and 4-aminopyridine. This comparison identified a clear correlation between template pK _a, degree of interaction and subsequent nonspecific binding in the nonimprinted polymer. Using FTIR spectroscopy it was also possible to observe the effect of temperature on the prepolymerisation solution. IR spectra showed that lower temperatures led to more stabilized interactions of the hydrogen-bonded complex. The potential advantages of FTIR spectroscopy compared with ¹H NMR spectroscopy in studying prepolymerisation solutions have been identified.

Keywords: Molecularly imprinted polymers; FTIR spectroscopy; Template–monomer interaction; Hydrogen bond; Aminopyridine

Thermal desorption characterisation of molecularly imprinted polymers. Part I: a novel study using direct-probe GC-MS analysis by Wayne Cummins; Patrick Duggan; Peter McLoughlin (pp. 1237-1244).

A novel thermal desorption technique using a direct-probe device (Chromatoprobe) attached to a gas chromatograph–mass spectrometer is presented for the thermal pretreatment, characterisation and analysis of molecularly imprinted polymers. The technique is demonstrated as effective for the removal of volatile materials, including template and unreacted monomers, from methacrylic acid–ethylene glycol dimethacrylate copolymers imprinted with 2-aminopyridine. Mass spectrometry is a powerful technique for polymer bleed characterisation. Thermal desorption studies on reloaded template and related compounds are reported as a means of assessing polymer morphology, specific binding by imprinted polymers compared with reference non-imprinted polymers and selective binding by an imprinted polymer for its template. Calibration studies on the thermal desorption technique using an internal standard are presented with R ² > 0.999. The technique provides a novel method for assessment of polymer thermal stability, composition and morphology.

Keywords: Molecular imprinting; Thermal desorption; Direct probe gas chromatography–mass spectrometry; Chromatoprobe; Polymer characterization; Aminopyridine

Thermal desorption characterisation of molecularly imprinted polymers. Part II: Use of direct probe GC–MS analysis to study crosslinking effects by Niamh Holland; Patrick Duggan; Eleanor Owens; Wayne Cummins; June Frisby; Helen Hughes; Peter McLoughlin (pp. 1245-1253).

A powerful method utilising direct probe thermal desorption GC–MS is presented for the study of molecularly imprinted polymers (MIPs). A series of 2-aminopyridine (2-apy)-imprinted methacrylic acid–ethyleneglycol dimethacrylate (MAA–EGDMA) copolymers were prepared under identical conditions but with varying amounts of EGDMA (crosslinking monomer). The use of appropriate temperature programmes permitted template removal, and the subsequent assessment of polymer affinity and specificity, all of which were found to be dependent on polymer composition and morphology. The system was sufficiently sensitive to identify a specific response of imprinted polymers over nonimprinted counterparts. Correlations were found to exist between thermal desorption analysis and solution phase binding, which was assessed by UV spectroscopy, where specificity was found to diminish with decreasing EGDMA concentration. This was attributed to the increased number of free carboxyl groups in those polymers containing a lower percentage of EGDMA. Thermal desorption profiles obtained for the analyte were found to be unaffected by the physical and chemical properties of the solvent used for analyte reloading.

Keywords: Molecular imprinting; Thermal desorption; Polymer characterisation; Polymer morphology; Affinity; Direct probe GC–MS

Optical enzyme sensor for determining l-lysine content using l-lysine oxidase from the rockfish Sebastes schlegeli by Hideaki Endo; Yoshitaka Hayashi; Yoichiro Kitani; Huifeng Ren; Tetsuhito Hayashi; Yuji Nagashima (pp. 1255-1261).

l-Lysine (l-Lys) in living bodies is critical for metabolism; therefore, determination of its levels in food is important. Most enzymatic methods for l-Lys analysis are performed using l-lysine oxidase (LyOx), but commercially manufactured LyOx is generally not highly selective for l-Lys among amino acids. We previously isolated LyOx as an antibacterial protein secreted from the skin of the rockfish Sebastes schlegeli. In the present study, we developed an optical enzyme sensor system for rapid and continuous determination of l-Lys using this LyOx. The system comprised an immobilized LyOx membrane, an optical oxygen probe, a flow system, and a personal computer. The amount of l-Lys was detected as a decrease in the oxygen concentration due to the LyOx reaction. The specificity of the sensor was examined against various amino acids. The sensor response was specific for l-Lys. Good reproducibility was obtained in 58 assays. The response of the sensor using commercially prepared LyOx was unstable compared with the response using LyOx isolated in our laboratory. Our sensor system could be used for 5 weeks without our having to change the enzyme membrane. The calibration curve for a standard l-Lys solution was linear from 0.1 to 3.0 mmol L⁻¹. One assay could be completed within 2 min. The sensor was applied to determine the l-Lys content in food samples such as bonito cooking water and scallop hepatopancreas. The values obtained using the sensor and conventional high-performance liquid chromatography methods were well correlated.

Keywords: Biosensor; Enzyme sensor; Lysine; Food; Fish

Electrochemical sensor with flavin-containing monooxygenase for triethylamine solution by Hirokazu Saito; Takeshi Shirai; Hiroyuki Kudo; Kohji Mitsubayashi (pp. 1263-1268).

A bioelectronic sensor for triethylamine (TEA) was developed with a flavin-containing monooxygenase type 3 (FMO-3). The TEA biosensor consisted of a Clark-type dissolved-oxygen electrode and an FMO-3 immobilized membrane. The FMO-3 solution was mixed with a poly(vinyl alcohol) containing stilbazolium groups (PVA-SbQ), coated on to the dialysis membrane, and the membrane was irradiated with a fluorescent light to immobilize the enzyme. In order to amplify the biosensor output, a substrate regeneration cycle, obtained by coupling the monooxygenase with l-ascorbic acid (AsA) as reducing reagent system, was applied. The effect of pH on the determination of TEA was studied. The maximum response was achieved at pH >9.0. A drop of the phosphate buffer solution with the AsA was put on the sensing area of the oxygen electrode, and the FMO-3 immobilized membrane was placed on the oxygen electrode and covered with a supporting Nylon mesh net which was secured with a silicone O-ring. A measurement system for TEA solution was constructed using the FMO-3 biosensor, a personal computer, a computer-controlled potentiostat, and an A/D converter. The FMO-3 biosensor was used to measure TEA solution from 0.5 to 4.0 mmol L⁻¹ with 10.0 mmol L⁻¹ AsA. The biosensor also had good reproducibility, for example a 6.31% coefficient of variation for five measurements, and the output current was maintained over a few hours. In order to improve the selectivity of the TEA biosensor, three type of biosensor with FMO isomer types 1, 3, and 5 were constructed and used to measure nitrogen and sulfur compounds. The outputs of the isomer biosensors indicated individual patterns for each sample solution. The selectivity of TEA biosensor would be improved, and determination of sulfur and nitrogen compounds would be possible, by using the different output of biosensors prepared from different FMO isomers.

Keywords: Biosensors; Enzymes; Triethylamine; Flavin-containing monooxygenase type 3; l-ascorbic acid; PVA-SbQ

Glucose sensor using a phospholipid polymer-based enzyme immobilization method by Hiroyuki Kudo; Tamon Yagi; Ming Xing Chu; Hirokazu Saito; Nobuyuki Morimoto; Yasuhiko Iwasaki; Kazunari Akiyoshi; Kohji Mitsubayashi (pp. 1269-1274).

An electroenzymatic glucose sensor based on a simple enzyme immobilization technique was constructed and tested. The glucose sensor measures glucose concentrations as changes of oxygen concentrations induced by enzymatic reactions. The immobilizing procedure was developed with the purpose of producing wearable biosensors for clinical use. Two types of biocompatible polymers, 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymerized with dodecyl methacrylate (PMD) and MPC copolymerized with 2-ethylhexyl methacrylat, were compared as a sensitive membrane of biosensors. The PMD enzyme membrane had a better response time. Linearity, reproducibility, effect of the concentrations of immobilized enzyme and drifts of sensor characteristics in long-term tests were also investigated. The linear characteristics were confirmed with glucose concentration from 0.01 to 2.00 mmol/l, with a coefficient of determination of 0.9999. The average output current for 1 mmol/l and the standard deviation were 0.992 and 0.0283 μA. Significant changes in the sensor's characteristics were not observed for 2 weeks when it was kept in a refrigerator at 4 °C. Because of the simple procedure, the enzyme immobilization method is not only useful for wearable devices but also other devices such as micro total analysis systems.

Keywords: Biosensor; Enzyme immobilization; Electroenzymatic; Electrochemical; Glucose sensor

Titania sol–gel-derived tyrosinase-based amperometric biosensor for determination of phenolic compounds in water samples. Examination of interference effects by J. Kochana; A. Gala; A. Parczewski; J. Adamski (pp. 1275-1281).

For detection of phenolic compounds in environmental water samples we propose an amperometric biosensor based on tyrosinase immobilized in titania sol–gel. The analytical characteristics toward catechol, p-cresol, phenol, p-chlorophenol, and p-methylcatechol were determined. The linear range for catechol determination was 2.2 × 10⁻⁷–1.3 × 10⁻⁵ mol L⁻¹ with a limit of detection of 9 × 10⁻⁸ mol L⁻¹ and sensitivity 2.0 × 10³ mA mol⁻¹ L. The influence of sample matrix components on the electrode response was studied according to Plackett–Burman experimental design. The potential interferents Mg²⁺, Ca²⁺, $$ { ext{HCO}}^{ - }_{3} $$ , $$ { ext{SO}}^{{2 - }}_{4} $$ , and Cl⁻, which are usually encountered in waters, were taken into account in the examination. Cu²⁺ was also taken into account, because CuSO₄ is sometimes added to a water sample, as a preservative, before determination of phenolic compounds. It was found that among the ions tested only Mg²⁺ and Ca²⁺ did not directly affect the electrode response. The developed biosensor was used for determination of catechol in spring and surface water samples using the standard addition method. Figure Cyclic voltammograms of the carbon electrode without and with titania gel layer. Supporting electrolite: 0.1 mol L^-1 phosphate buffer solution pH7; scan rate 500 mV s^-1.

Keywords: Tyrosinase; Amperometric biosensor; Phenols; Plackett–Burman design

Disposable electrochemical flow cells for catalytic adsorptive stripping voltammetry (CAdSV) at a bismuth film electrode (BiFE) by Nahid Gharib Naseri; Sara J. Baldock; Anastasios Economou; Nicholas J. Goddard; Peter R. Fielden (pp. 1283-1292).

Catalytic adsorptive stripping voltammetry (CAdSV) has been demonstrated at a bismuth film electrode (BiFE) in an injection-moulded electrochemical micro-flow cell. The polystyrene three-electrode flow cell was fabricated with electrodes moulded from a conducting grade of polystyrene containing 40% carbon fibre, one of which was precoated with Ag to enable its use as an on-chip Ag/AgCl reference electrode. CAdSV of Co(II) and Ni(II) in the presence of dimethylglyoxime (DMG) with nitrite employed as the catalyst was performed in order to assess the performance of the flow cell with an in-line plated BiFE. The injection-moulded electrodes were found to be suitable substrates for the formation of BiFEs. Key parameters such as the plating solution matrix, plating flow rate, analysis flow rate, solution composition and square-wave parameters have been characterised and optimal conditions selected for successful and rapid analysis of Co(II) and Ni(II) at the ppb level. The analytical response was linear over the range 1 to 20 ppb and deoxygenation of the sample solution was not required. The successful coupling of a microfluidic flow cell with a BiFE, thereby forming a “mercury-free” AdSV flow analysis sensor, shows promise for industrial and in-the-field applications where inexpensive, compact, and robust instrumentation capable of low-volume analysis is required.

Keywords: Bismuth film electrode (BiFE); Square-wave adsorptive stripping voltammetry; Cobalt; Nickel; Dimethylglyoxime; Electrochemical detection; Flow cell; Channel; Injection moulding; Sensor

Multiresidue methods for the analysis of pharmaceuticals, personal care products and illicit drugs in surface water and wastewater by solid-phase extraction and ultra performance liquid chromatography–electrospray tandem mass spectrometry by Barbara Kasprzyk-Hordern; Richard M. Dinsdale; Alan J. Guwy (pp. 1293-1308).

The main aim of the presented research is to introduce a new technique, ultra performance liquid chromatography–positive/negative electrospray tandem mass spectrometry (UPLC–ESI/MS/MS), for the development of new simultaneous multiresidue methods (over 50 compounds). These methods were used for the determination of multiple classes of pharmaceuticals (acidic, basic and neutral compounds: analgesic/anti-inflammatory drugs, antibiotics, antiepileptics, beta-adrenoceptor blocking drugs, lipid regulating agents, etc.), personal care products (sunscreen agents, preservatives, disinfectant/antiseptics) and illicit drugs (amphetamine, cocaine and benzoylecgonine) in surface water and wastewater. The usage of the novel UPLC system with a 1.7 μm particle-packed column allowed for good resolution of analytes with the utilisation of low mobile phase flow rates (0.05–0.07 mL min⁻¹) and short retention times (method times of up to 25 min), delivering a fast and cost-effective method. SPE with the usage of Oasis MCX strong cation-exchange mixed-mode polymeric sorbent was chosen for sample clean-up and concentration. The influence of mobile phase composition, matrix-assisted ion suppression in ESI–MS and SPE recovery on the sensitivity of the method was extensively studied. The method limits of quantification were at low nanogram per litre levels and ranged from tenths of ng L⁻¹ to tens of ng L⁻¹ in surface water and from single ng L⁻¹ to a few hundreds of ng L⁻¹ in the case of wastewater. The instrumental and method intraday and interday repeatabilities were on average less than 5%. The method was successfully applied for the determination of pharmaceuticals in the River Taff (South Wales) and a wastewater treatment plant (WWTP Cilfynydd). Several pharmaceuticals and personal care products were determined in river water at levels ranging from single ng L⁻¹ to single μg L⁻¹.

Keywords: Pharmaceuticals; Personal care products; Illicit drugs; Ultra performance liquid chromatography–tandem mass spectrometry; Solid-phase extraction; Multiresidue method; Ion suppression

Analysis of cocaine and its principal metabolites in waste and surface water using solid-phase extraction and liquid chromatography–ion trap tandem mass spectrometry by Adriana Gheorghe; Alexander van Nuijs; Bert Pecceu; Lieven Bervoets; Philippe G. Jorens; Ronny Blust; Hugo Neels; Adrian Covaci (pp. 1309-1319).

A validated method based on solid-phase extraction (SPE) and liquid chromatography–ion trap tandem mass spectrometry (LC-MS/MS) is described for the determination of cocaine (COC) and its principal metabolites, benzoylecgonine (BE) and ecgonine methyl ester (EME), in waste and surface water. Several SPE adsorbents were investigated and the highest recoveries (95.7 ± 5.5, 91.8 ± 2.2 and 72.5 ± 5.3% for COC, BE and EME, respectively) were obtained for OASIS HLB® cartridges (6 mL/500 mg) using 100 mL of waste water or 500 mL of surface water. Extracts were analysed by reversed-phase (RP) or hydrophilic interaction (HILIC) LC-MS/MS in positive ion mode with multiple reactions monitoring (MRM); the latter is the first reported application of the HILIC technique for drugs of abuse in water samples. Corresponding deuterated internal standards were used for quantification. The method limits of quantification (LOQs) for COC and BE were 4 and 2 ng L⁻¹, respectively, when RPLC was used and 1, 0.5 and 20 ng L⁻¹ for COC, BE and EME, respectively, with the HILIC setup. For COC and BE, the LOQs were below the concentrations measured in real water samples. Stability tests were conducted to establish the optimal conditions for sample storage (pH, temperature and time). The degradation of COC was minimal at −20 °C and pH = 2, but it was substantial at +20 °C and pH = 6. The validated method was applied to a set of waste and surface water samples collected in Belgium. Figure While human and veterinary pharmaceutical compounds have been monitored in the environment for more than 10 years, the detection of drugs of abuse in waste and surface water samples has only recently surfaced. The measurement of cocaine and metabolites in environmental water samples is an innovative approach for the estimation of cocaine consumption by the general population.

Keywords: Cocaine; Metabolites; LC-MS/MS; Waste water; Analytical method; Validation; HILIC

Stalked protozoa identification by image analysis and multivariable statistical techniques by A. L. Amaral; Y. P. Ginoris; A. Nicolau; M. A. Z. Coelho; E. C. Ferreira (pp. 1321-1325).

Protozoa are considered good indicators of the treatment quality in activated sludge systems as they are sensitive to physical, chemical and operational processes. Therefore, it is possible to correlate the predominance of certain species or groups and several operational parameters of the plant. This work presents a semiautomatic image analysis procedure for the recognition of the stalked protozoa species most frequently found in wastewater treatment plants by determining the geometrical, morphological and signature data and subsequent processing by discriminant analysis and neural network techniques. Geometrical descriptors were found to be responsible for the best identification ability and the identification of the crucial Opercularia and Vorticella microstoma microorganisms provided some degree of confidence to establish their presence in wastewater treatment plants.

Keywords: Protozoa; Metazoa; Activated sludge; Image analysis; Multivariable statistical techniques

Granitic groundwater colloids sampling and characterisation: the strategy for artefact elimination by A. C. Nilsson; I. Hedqvist; C. Degueldre (pp. 1327-1333).

Colloids were separated by submicro-filtration of granitic groundwater samples collected at-line under in-situ thermodynamic conditions after down-hole groundwater sampling and transfer at the well head. The methodology avoids the generation of artefacts produced by pH changes due to CO₂ exchange, yielding potential carbonate precipitation, or by O₂ contamination yielding oxidized insoluble phases. The enhanced pressure and the anoxic conditions are also maintained through the filtering procedure. This procedure was carried out after a period of regular sampling of groundwater pumped to the ground surface and continuous on-line long-term measurements (weeks, months) of chemical and physical parameters in the unbroken sample water both at the ground surface and at depth down-hole. Colloid samples were characterized on the submicro-filtration membrane by scanning electron microscopy. Under deep granite groundwater conditions, natural colloids occur sparsely. The colloid concentration was determined C _col ∼1 and ∼50 μg L⁻¹ for sizes ranging from 50 to 200 nm or n _col ∼ 3.9 × 10⁹ and 47 × 10⁹ L⁻¹ for sizes larger than 50 nm for KFM11A, Forsmark, and KLX17A, Laxemar, Oskarshamn, respectively, Sweden. These colloids are expected to be clay particles with an average size smaller than 200 nm for the Na-Ca-Cl and Na-Cl groundwaters (pH 7.6 and 8.00, ionic strength ∼10⁻¹ and ∼10⁻² mol L⁻¹, respectively, for KFM11A and KLX17A), the colloid concentrations were comparable with values previously reported in the literature.

Keywords: Aerosols/particulates; Electron/ion microprobe; Imaging (NMR microscopy/electron microscopy); Nanoparticles/nanotechnology; Geochemistry/geology

Organosilica composite for preconcentration of phenolic compounds from aqueous solutions by V. N. Zaitsev; V. A. Khalaf; G. N. Zaitseva (pp. 1335-1342).

A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO₂) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol) (TX). Under static conditions phenol was quantitatively extracted onto TX-SiO₂ in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO₂ for phenol is 2.4 mg g⁻¹ with distribution coefficients up to 3.4 × 10⁴ mL g⁻¹; corresponding data for 1-naphthol are 1.5 mg g⁻¹ and 3 × 10³ mL g⁻¹. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than 0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A ₅₄₀) and phenol concentration (C) in water was found according to the equation A ₅₄₀ = (6 ± 1) × 10⁻² + (0.9 ± 0.1)C (μmol L⁻¹) with a detection range from 1 × 10⁻⁸ mol L⁻¹ (0.9 μL g⁻¹) to 2 × 10⁻⁷ mol L⁻¹ (19 μL g⁻¹), a limit of quantification of 1 μL g⁻¹ (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical analysis. The detection limit of 1-naphthol with this method is 6 μL g⁻¹ while the quantification limit is 20 μL g⁻¹. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g⁻¹.

Keywords: Organosilica composite; Solid-phase extraction; Phenol; 1-Naphthol; Ion associate; Naked eye test method

Investigating morphological changes in treated vs. untreated stone building materials by x-ray micro-CT by Simone Bugani; Mara Camaiti; Luciano Morselli; Elke Van de Casteele; Koen Janssens (pp. 1343-1350).

Calcareous stones have been largely used to build historical buildings. Among these, the calcarenites are usually characterized by a high content of calcite and a high open porosity, which make them very sensitive to the weathering caused by physical and chemical agents. In order to prevent their deterioration and to retard their decay, different protective products—mainly polymers—are applied on the stone artefact surfaces. In this work we apply the methodology tested in a preliminary study to investigate the morphological changes of the internal structure of a biocalcarenite (Lecce stone) by micro x-ray computed tomography (μ-CT). The porosity and other morphological parameters of the rock before and after the conservation treatment were calculated on a significant number of samples. The Student’s t test was applied for statistical comparison. The results reveal that the treatment with Paraloid B72 (PB 72) is homogenously distributed and causes small changes to the natural properties of the rock, whereas the application of a fluoroelastomer (NH) causes an appreciable decrease in porosity and variation in terms of wall thickness distribution, probably resulting from its inhomogeneous distribution. Figure Porosity and other morphological parameters of Lecce stone were investigated by μ-CT: the effect of conservation treatment with fluoroelastomer on wall thickness distribution is illustrated

Keywords: Cultural heritage; Stone conservation; Calcarenite; Porosity; Morphological parameters; Protective treatments; μ-CT

Study of ageing of ketone resins used as picture varnishes by FTIR spectroscopy, UV–Vis spectrophotometry, atomic force microscopy and scanning electron microscopy X-ray microanalysis by María Teresa Doménech-Carbó; Dolores Julia Yusá-Marco; Giovanna Bitossi; Miguel F. Silva; Xavier Mas-Barberá; Laura Osete-Cortina (pp. 1351-1359).

This paper presents a study of thin films of the commercial ketone resins Laropal K80, Keton N and MS2A, attempting to reproduce the pictorial layers and protective finishes commonly present in contemporary paintings. Chemical and morphological changes due to the degradation effect of environmental agents have been specially considered. For this purpose, three different accelerated ageing processes were applied to a series of specimens prepared from the studied commercial products: thermal, UV light and ageing in an SO₂-polluted chamber. Spectroscopic techniques such as FTIR spectroscopy and UV–Vis spectrophotometry were applied in combination with microscopic examination techniques, namely, AFM and scanning electron microscopy energy dispersive X-ray microanalysis (SEM-EDX). Chemical changes due to UV light and thermal ageing are in good agreement with those previously reported in the literature. Bleaching exhibited by the three commercial products after exposure to a SO₂-saturated atmosphere has been related to the diffusion of SO₂-rich water vapour into the film. This effect was particularly strong in the MS2A resin due to the higher content of hydroxyl groups in this product.

Keywords: FTIR spectroscopy; UV–Vis spectrophotometry; Scanning electron microscopy energy dispersive X-ray microanalysis; Atomic force microscopy; Ketone varnish

Analytical diagnosis methodology to evaluate nitrate impact on historical building materials by M. Maguregui; A. Sarmiento; I. Martínez-Arkarazo; M. Angulo; K. Castro; G. Arana; N. Etxebarria; J. M. Madariaga (pp. 1361-1370).

Nitrate salts have become of greater importance in the decay of materials from historical buildings due to changes in the environment. This work presents an analytical diagnosis methodology to evaluate the impact of nitrate salts in mortars and bricks, combining noninvasive and microdestructive analytical techniques together with chemometric and thermodynamic data analyses. The impact of nitrate salts cannot be well ascertained if other soluble salts are not taken into account. Therefore, the principal results from this work relate to nitrate salts but some results for other kinds of salts are included. Data from Raman microprobe spectroscopy and micro X-ray fluorescence (μ-XRF) are used to characterise the original composition and a first approximation of the nature of the decay compounds, mainly nitrates. The soluble salts are extracted and the anions and cations are quantified by means of ion chromatography with conductimetric detection for anions/cations and inductively coupled plasma mass spectrometry (ICP/MS) for cations. The values obtained allow two different data treatments to be applied. First, chemometric analysis is carried out to search for correlations among anions and cations. Second, thermodynamic modelling with the RUNSALT program is performed to search for environmental conditions of soluble salt formation. All the results are finally used to diagnose the impact of nitrates.

Keywords: Mortar; Brick; Raman microprobre; Micro X-ray fluorescence; Ion chromatography

Characterization of polyvinyl resins used as binding media in paintings by pyrolysis–silylation–gas chromatography–mass spectrometry by Maria Teresa Doménech-Carbó; Giovanna Bitossi; Laura Osete-Cortina; Juana de la Cruz-Cañizares; Dolores Julia Yusá-Marco (pp. 1371-1379).

Polyvinyl resins, in particular poly(vinyl acetate) emulsions (PVA), are widely used in contemporary paintings as binding media, because of the optimum mechanical and optical properties these polymers confer on the paint layers. A study has been carried out to chemically characterize samples of PVA resins prepared as coating films from commercial products currently available from fine arts suppliers. For this purpose, a new method has been based on “on-line” silylation–pyrolysis using hexamethyldisilazane as derivatisation reagent in pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS). This proposed procedure leads to unambiguous identification of this type of binder and improves conventional direct Py–GC–MS. PVA media used in three contemporary paintings from a private collection and from the Museum of Fine Arts of Málaga (Spain) have been successfully identified with this procedure. As a second step of this work, a study devoted to the characterization of changes in the chemical composition of the PVA commercial products studied has been carried out. Effects induced in the specimens by three different types of artificial accelerated ageing process—thermal, UV light, and in an SO₂-polluted chamber—were compared.

Keywords: Archeometry; Fine arts; Py-GC-MS; Synthetic polymers; Binding media; Silylation; Poly(vinyl acetate)

Combining TXRF, FT-IR and GC–MS information for identification of inorganic and organic components in black pigments of rock art from Alero Hornillos 2 (Jujuy, Argentina) by Cristina Vázquez; Marta S. Maier; Sara D. Parera; Hugo Yacobaccio; Patricia Solá (pp. 1381-1387).

Archaeological samples are complex in composition since they generally comprise a mixture of materials submitted to deterioration factors largely dependent on the environmental conditions. Therefore, the integration of analytical tools such as TXRF, FT-IR and GC–MS can maximize the amount of information provided by the sample. Recently, two black rock art samples of camelid figures at Alero Hornillos 2, an archaeological site located near the town of Susques (Jujuy Province, Argentina), were investigated. TXRF, selected for inorganic information, showed the presence of manganese and iron among other elements, consistent with an iron and manganese oxide as the black pigment. Aiming at the detection of any residual organic compounds, the samples were extracted with a chloroform–methanol mixture and the extracts were analyzed by FT-IR, showing the presence of bands attributable to lipids. Analysis by GC–MS of the carboxylic acid methyl esters prepared from the sample extracts, indicated that the main organic constituents were saturated (C_16:0 and C_18:0) fatty acids in relative abundance characteristic of degraded animal fat. The presence of minor C_15:0 and C_17:0 fatty acids and branched-chain iso-C_16:0 pointed to a ruminant animal source. Figure Rock art painting at Hornillos 2 Cave, Susques, Argentina

Keywords: Prehistoric rock art; Inorganic and organic components; TXRF; FT-IR; GC–MS

Compositional analysis of Tuscan glass samples: in search of raw material fingerprints by S. Cagno; K. Janssens; M. Mendera (pp. 1389-1395).

SEM-EDX quantitative analyses were performed on 91 samples of vessel glass originating from a number of sites throughout Tuscany. A comparison with Venetian glass data is made in order to evaluate differences in glassmaking materials. The compositions of the samples provide clues about the different raw materials used in relation to recipes that changed slightly during the period covering the late Middle Ages to early Renaissance. Two kinds of ash used as a fluxing agent were identified, one of which is of east Mediterranean origin while the other is likely to be Spanish. Two types of silica sources were also found. One of these was recognized as being quartziferous river pebbles, while the other is proposed to be local sand.

Keywords: Archaeometry/fine arts; Glass; Tuscany; Venice; Electron microprobe; X-ray spectroscopy (EDX); SEM-EDX

Results of a European inter-laboratory comparison study on the determination of EU priority polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils by Rupert Simon; José Angel Gomez Ruiz; Christoph von Holst; Thomas Wenzl; Elke Anklam (pp. 1397-1408).

A collaborative study on the analysis for 15 + 1 EU priority PAHs in edible oils was organised to investigate the state-of-the-art of respective analytical methods. Three spiked vegetable oils, one contaminated native sunflower oil, and one standard solution were investigated in this study. The results of 52 laboratories using either high-performance liquid chromatography with fluorescence detection or gas chromatography with mass-selective detectors were evaluated by application of robust statistics. About 95% of the laboratories were able to quantify benzo[a]pyrene together with five other PAHs included in the commonly known list of 16 US-EPA PAHs. About 80% of the participants also quantified seven additional PAHs in most samples, two of which were benzo[b]fluoranthene and benzo[k]fluoranthene, which were also known from the EPA list. Only about 50% of the participants quantified cyclopenta[cd]pyrene, benzo[j]fluoranthene, and benzo[c]fluorene. The robust relative standard deviations of the submitted results without discrimination between the methods applied ranged between 100% for 5-methylchrysene in spiked olive oil and 11% for the same analyte in spiked sunflower oil. The results clearly showed that for these analytes the methods of analysis are not yet well established in European laboratories, and more collaborative trials are needed to promote further development and to improve the performances of the respective methods.

Keywords: Polycyclic aromatic hydrocarbons (PAHs); European priority PAHs; Edible vegetable oils; Inter-laboratory comparison study

Sampling of benzene in tar matrices from biomass gasification using two different solid-phase sorbents by Sergejs Osipovs (pp. 1409-1417).

Biomass tar mainly consists of stable aromatic compounds such as benzene and polyaromatic hydrocarbons, benzene being the biggest tar component in real biomass gasification gas. For the analysis of individual tar compounds, the solid-phase adsorption method was chosen. According to this method, tar samples are collected on a column with an amino-phase sorbent. With a high benzene concentration in biomass tar, some of the benzene will not be collected on the amino-phase sorbent. To get over this situation, we have installed another column with activated charcoal which is intended for collection of volatile organic compounds, including benzene, after the column with the amino-phase sorbent. The study of maximal adsorption amounts of various compounds on both adsorbents while testing different sampling volumes led to the conclusion that benzene is a limiting compound. The research proved that the use of two sorbents (500 mg + 100 mg) connected in series allows for assessment of tar in synthesis gas with a tar concentration up to 30–40 g m⁻³, which corresponds to the requirements of most gasifiers.

Keywords: Sampling; Gas chromatography; Tar; Biomass; Gasification; Benzene

Evaluation of solid-phase microextraction conditions for the determination of polycyclic aromatic hydrocarbons in aquatic species using gas chromatography by N. Aguinaga; N. Campillo; P. Viñas; M. Hernández-Córdoba (pp. 1419-1424).

This paper describes a headspace solid-phase microextraction (HS-SPME) procedure coupled to gas chromatography with mass spectrometric detection (GC–MS) for the determination of eight PAHs in aquatic species. The influence of various parameters on the PAH extraction efficiency was carefully examined. At 75 °C and for an extraction time of 60 min, a polydimethylsiloxane–divinylbenzene (PDMS/DVB) fiber coating was found to be most suitable. Under the optimized conditions, detection limits ranged from 8 to 450 pg g⁻¹, depending on the compound and the sample matrix. The repeatability varied between 7 and 15% (RSD). Accuracy was tested using the NIST SRM 1974b reference material. The method was successfully applied to different samples, and the studied PAHs were detected in several of the samples. Figure Headspace SPME sampling followed by GC–MS facilitates routine monitoring of PAHs in aquatic species

Keywords: Polycyclic aromatic hydrocarbons; Headspace solid-phase microextraction; Gas chromatography; Mass spectrometry; Aquatic species

Solid-phase microextraction for the gas chromatography mass spectrometric determination of oxazole fungicides in malt beverages by Pilar Viñas; Natalia Campillo; Nerea Aguinaga; Nelson Martínez-Castillo; Manuel Hernández-Córdoba (pp. 1425-1431).

This paper describes a method for the sensitive, selective, and solvent-free determination of six oxazole fungicide residues (hymexazol, drazoxolon, vinclozolin, chlozolinate, oxadixyl, and famoxadone) in malt beverages. Direct immersion solid-phase microextraction (DI-SPME) coupled to gas chromatography with mass spectrometry in the selected ion monitoring mode, GC-MS(SIM), is used. A comparison of the optimal fiber used, a polar carbowax–divinylbenzene 70-μm fiber, and a nonpolar polydimethylsiloxane 100-μm fiber was carried out. Optimal extraction conditions were 60 °C and an extraction time of 30 min under continuous stirring. Desorption was carried out at 250 °C for 5 min. Detection limits ranged from 0.006 to 0.3 μg L⁻¹ at a signal to noise ratio of 3, depending on the compound. The proposed method was successfully applied to malt beverages including malt, beer, and whisky, and none of the samples contained residues higher than detection limits. Figure Elution profile obtained for a spiked malt beverage by using DI-SPME-GC-MS

Keywords: Oxazole fungicides; Solid-phase microextraction; Direct immersion; Gas chromatography; Mass spectrometry; Malt beverages

Determination of heterocyclic aromatic amines by capillary high-performance liquid chromatography with diode array detection in ready-to-eat cooked ham treated with electron-beam irradiation by N. Rosales-Conrado; M. E. León-Gonzáles; L. V. Pérez-Arribas; L. M. Polo-Díez (pp. 1433-1442).

Heterocyclic aromatic amines (HAs) are a group of mutagenic and carcinogenic substances present in significant amounts in cooked meat and fish that can potentially be formed during food processing operations. This paper proposes a capillary liquid chromatography method with diode array detection for the trace-level determination of three HAs, namely, MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), norharman (9H-pyrido[3,4-b]indole) and harman (1-methyl-9H-pyrido[3,4-b]indole), in ready-to-eat (RTE) cooked ham processed by electron-beam (accelerated electrons) irradiation to eliminate pathogenic microorganisms and to extend its shelf-life. The HAs selected have frequently been detected and quantified in a wide range of food and could be potential markers to indicate the presence of these toxic compounds. The method is based on the separation in an Inertsil C₈ capillary column (150 mm × 0.3-mm internal diameter, 3 μm) by gradient elution mode using a mixture of acetonitrile and 30 mM ammonium acetate pH 4.5 buffer as the mobile phase. Detection was at 250 and 265 nm and, to improve sensitivity, large injection volumes (20 μL) and on-column focusing techniques based on the injection of HA samples in low organic solvent strength solutions were employed. A simple and short solid-phase extraction and purification procedure was also optimized for sample preparation. Nonirradiated and irradiated RTE cooked ham samples at doses between 1 and 8 kGy were analyzed. HAs were not detected in any of the samples analyzed; so both types of samples were spiked at concentration levels in the range 5–25 ng g⁻¹, which may be found in meat products. The quality parameters of the method developed in the food matrix were established, and detection limits around 0.3 ng g⁻¹ were obtained. Spiked recoveries between 70 and 79% (n = 3 for each spiked level) relative standard deviations between 1 and 5% were also obtained, showing the effectiveness of the proposed method.

Keywords: Heterocyclic amines; Capillary liquid chromatography; Irradiation; Ready-to-eat foods; Cooked ham

Comparative study of screening methodologies for ochratoxin A detection in winery by-products by E. Ribeiro; A. Alves (pp. 1443-1450).

The worldwide contamination of winery by-products by mycotoxins may present a serious hazard to human and animal health. Mycotoxins are secondary metabolites of fungi with possible adverse effects on humans, animals, and crops that result in illnesses and economic losses. Mycotoxins are under continuous survey in Europe, but the regulatory aspects still need to be set up for winery by-products, which may be used in animal feed. The aim of this study was to implement a simple but reliable analytical methodology for ochratoxin A (OTA) quantification in grape pomaces in order to perform a survey of samples from the Douro Demarcated Region, Portugal. The method involved a unique preparation step, solvent extraction, followed by high-performance liquid chromatography (HPLC) with fluorescence (FL) detection. A comparative study was performed with two extraction solvents (ethyl acetate and methanol) as well as using extraction on an immunoaffinity column. The linearity range for OTA analysis was 0.05–23.5 μg L⁻¹ with a detection limit of 0.05 μg L⁻¹ and a precision (expressed by the coefficient of variation under repeatability conditions) of 0.4–14.7%. The percentage of recovery was on average 23.5 ± 3.6% (extraction with ethyl acetate) or 70.1 ± 2.5% (extraction with 70% methanol). Accounting for the recovery factor and the chromatographic detection limit, as well as the preconcentration factor, the limit of detection in grape pomaces is 0.04 μg kg⁻¹ (ethyl acetate extraction) and 0.33 μg kg⁻¹ (methanol extraction). Samples from 12 out of 13 sites in the Douro Demarcated Region showed OTA presence with concentrations not exceeding 0.4 μg kg⁻¹. Both developed methods for evaluation of OTA in grape pomace are simple but efficient. Figure Extraction of ochratoxin A (OTA) from grape pomaces allows simple but efficient quantification of OTA in winery by-products by HPLC-FL

Keywords: Winery by-products; Grape pomace; Ochratoxin A; HPLC; Fluorescence detection

Chemiluminescent determination of EDTA and related compounds using tris(2,2′-bipyridyl)ruthenium(III) photogenerated on-line by Tomás Pérez-Ruiz; Carmen Martínez-Lozano; María Dolores García-Martínez (pp. 1451-1457).

A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of EDTA. The method is based on the chemiluminescent reaction of EDTA with tris(2,2′-bipyridyl)ruthenium(III), which is generated on-line through the photooxidation of tris(2,2′-bipyridyl)ruthenium(II) with peroxydisulfate. After optimizing the different experimental parameters, a calibration graph was obtained over the concentration range of 7 × 10⁻⁸ M to 3 × 10⁻⁶ M, with a minimum detectability of 7.2 × 10⁻⁹ M (S/N = 3) observed. The correlation coefficient was 0.9992 (n = 8). The repeatability was 0.88 % (for a level of 4 × 10⁻⁷ M) expressed as the relative standard deviation (n = 10), and the reproducibility (studied on five consecutive days) was 1.5 %. The method was successfully applied to the determination of EDTA in ophthalmic collyrium and sauce samples. The method is also useful for determining other aminopolycarboxylic acids, such as NTA, EGTA, DTPA, DCTA and EDDS.

Keywords: Aminopolycarboxylic acids; EDTA; Flow injection; Chemiluminescence; Photogenerated tris(2,2′-bipyridyl)ruthenium(III); Pharmaceutical and food analysis

Particulate matter analysis at elementary schools in Curitiba, Brazil by Devanir Avigo Jr.; Ana F. L. Godoi; Paulo R. Janissek; Yaroslava Makarovska; Agnieszka Krata; Sanja Potgieter-Vermaak; Balint Alfoldy; René Van Grieken; Ricardo H. M. Godoi (pp. 1459-1468).

The particulate matter indoors and outdoors of the classrooms at two schools in Curitiba, Brazil, was characterised in order to assess the indoor air quality. Information concerning the bulk composition was provided by energy-dispersive x-ray fluorescence (EDXRF). From the calculated indoor/outdoor ratios and the enrichment factors it was observed that S-, Cl- and Zn-rich particles are of concern in the indoor environment. In the present research, the chemical compositions of individual particles were quantitatively elucidated, including low-Z components like C, N and O, as well as higher-Z elements, using automated electron probe microanalysis low Z EPMA. Samples were further analysed for chemical and morphological aspects, determining the particle size distribution and classifying them according to elemental composition associations. Five classes were identified based on major elemental concentrations: aluminosilicate, soot, organic, calcium carbonate and iron-rich particles. The majority of the respirable particulate matter found inside of the classroom was composed of soot, biogenic and aluminosilicate particles. In view of the chemical composition and size distribution of the aerosol particles, local deposition efficiencies in the human respiratory system were calculated revealing the deposition of soot at alveolar level. The results showed that on average 42% of coarse particles are deposited at the extrathoracic level, whereas 24% are deposited at the pulmonary region. The fine fraction showed a deposition rate of approximately 18% for both deposition levels.

Keywords: Indoor environment; Particulate matter; Schools; Lung deposition

Use of sodium tungstate as a permanent chemical modifier for slurry sampling electrothermal atomic absorption spectrometric determination of indium in soils by Ignacio López-García; Ricardo E. Rivas; Manuel Hernández-Córdoba (pp. 1469-1474).

A number of chemical modifiers have been assessed for the direct determination of indium in soils using electrothermal atomic absorption spectrometry and slurry sampling. The best results were obtained when the graphite atomizer was impregnated with sodium tungstate, which acts as a permanent chemical modifier. Slurries were prepared by suspending 100 mg sample in a solution containing 1% (v/v) concentrated nitric acid and 10% (v/v) concentrated hydrofluoric acid and then 15-μL aliquots were directly introduced into the atomizer. Standard indium solutions prepared in the suspension medium in the range 4–80 μg L^-1 indium were used for calibration. The relative standard deviation for ten consecutive measurements of a 40 μg L^-1 indium solution was 2.8%. The limit of detection in soils was 0.1 μg g^-1. The reliability of the procedures was confirmed by analysing two standard reference materials and by using an alternative procedure. Figure “The use of HF in some slurry-ETTAS procedures avoids platform deterioration”

Keywords: Electrothermal atomic absorption spectrometry; Indium; Chemical modifiers; Slurry sampling; Soils

Sections

Personal tools

Analytical and Bioanalytical Chemistry (v.391, #4)

Sections

Personal tools

Local resources

Analytical and Bioanalytical Chemistry (v.391, #4)