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Analytical and Bioanalytical Chemistry (v.387, #4)

Pharmaceuticals and personal care products (PPCPs) in the environment by Damià Barceló; Mira Petrovic (pp. 1141-1142).

is full Research Professor at IIQAB-CSIC and Head of the Environmental Chemistry Department. His scientific focus is on method development and the monitoring and fate of priority, new and emerging pollutants, including endocrine-disrupting compounds using GC and LC techniques coupled to advanced tandem and hybrid mass spectrometric analysis combined with bioassays, biosensors and endocrine effect studies. is an ICREA Research Professor at the Department of Environmental Chemistry, IIQAB-CSIC, Barcelona, Spain. Her main expertise is in the field of analytical environmental chemistry, specifically analysis of organic micropollutants by advance mass spectrometric techniques and study of their fate and behaviour in the aquatic environment and during wastewater and drinking water treatment.

Trends in the detection of pharmaceutical products, and their impact and mitigation in water and wastewater in North America by Isabelle Robinson; Guillaume Junqua; Raymond Van Coillie; Olivier Thomas (pp. 1143-1151).

Trends in monitoring pharmaceuticals and personal-care products in the aquatic environment by use of passive sampling devices by Graham A. Mills; Branislav Vrana; Ian Allan; David A. Alvarez; James N. Huckins; Richard Greenwood (pp. 1153-1157).

Occurrence and analysis of pharmaceuticals and their transformation products in drinking water treatment by C. Zwiener (pp. 1159-1162).

Integrated approach to the problem of pharmaceutical products in the environment: an overview by Clemence Coetsier; Liming Lin; Benoit Roig; Evelyne Touraud (pp. 1163-1166).

Trends in human risk assessment of pharmaceuticals by J. L. C. M. Dorne; A. M. J. Ragas; G. K. Frampton; D. S. Spurgeon; D. F. Lewis (pp. 1167-1172).

Pharmaceuticals and personal care products in biosolids/sewage sludge: the interface between analytical chemistry and regulation by T. L. Jones-Lepp; Rick Stevens (pp. 1173-1183).

Modern sanitary practices result in large volumes of human waste, as well as domestic and industrial sewage, being collected and treated at common collection points, wastewater treatment plants (WWTPs). In recognition of the growing use of sewage sludge as fertilizers and soil amendments, and the scarcity of current data regarding the chemical constituents in sewage sludge, the US National Research Council (NRC) in 2002 produced a report on sewage sludge. Among the NRC’s recommendations was the need for investigating the occurrence of pharmaceuticals and personal care products (PPCPs) in sewage sludge. PPCPs are a diverse array of non-regulated contaminants that had not been studied in previous sewage sludge surveys but which are likely to be present. The focus of this paper will be to review the current analytical methodologies available for investigating whether pharmaceuticals are present in WWTP-produced sewage sludge, to summarize current regulatory practices regarding sewage sludge, and to report on the presence of pharmaceuticals in sewage sludge.

Keywords: Biosolids; Sewage sludge; Pharmaceuticals; Analytical chemistry

Determination of non-steroidal anti-inflammatory drugs in environmental samples by chromatographic and electrophoretic techniques by Alessandra Gentili (pp. 1185-1202).

Non-steroidal anti-inflammatory drugs (NSAIDs) are a group of pharmaceutical compounds widely used in human health care and often found in the aquatic environment, with their metabolites. After an introduction that describes the general problem of drug contamination, the properties of NSAIDs, and environmental risk assessment, this review surveys the chromatographic and electrophoretic methods of analysis in use today for monitoring the most important representatives of this pharmaceutical class in different environmental samples.

Keywords: NSAIDs; Chromatographic techniques; Electrophoretic techniques; Mass spectrometric detection; Environmental samples

Recently developed GC/MS and LC/MS methods for determining NSAIDs in water samples by M. Farré; M. Petrovic; D. Barceló (pp. 1203-1214).

Pharmaceuticals have become major targets in environmental chemistry due to their presence in aquatic environments (following incomplete removal in wastewater treatment or point-source contaminations), threat to drinking water sources and concern about their possible effects to wildlife and humans. Recently several methods have been developed for the determination of drugs and their metabolites in the lower nanogram per litre range, most of them using solid-phase extraction (SPE) or solid-phase microextraction (SPME), derivatisation and finally gas chromatography mass spectrometry (GC-MS), gas chromatography tandem mass spectrometry (GC-MS/MS) and liquid chromatography electrospray tandem mass spectrometry (LC-ES/MS/MS). Due to the elevated polarity of non-steroidal anti-inflamatory drugs (NSAIDs), analytical techniques based on either liquid chromatography coupled to mass spectrometry (LC-MS) and gas chromatography coupled to mass spectrometry (GC-MS) after a previous derivatisation step are essential. The most advanced aspects of current GC-MS, GC-MS/MS and LC-MS/MS methodologies for NSAID analysis are presented.

Keywords: Pharmaceuticals; GC/MS; LC/MS; Wastewater; Surface water

SPR-based biosensors: a tool for biodetection of hormonal compounds by Denis Habauzit; Joel Chopineau; Benoit Roig (pp. 1215-1223).

Novel cancer treatments, prevention of postmenopausal disorder, and prescription of oral contraceptives are the main developments in the design of synthetic estrogenic medication. The increasing consumption of these synthetic pharmaceuticals, in addition to human and animal natural estrogenic compound excretion, contribute to their environmental dissemination worldwide. Their assimilation as a result of consumption of food and water perturbs normal endocrine systems and leads to the emergence of human and animal diseases and malformations. These compounds are active in the organism at low concentrations. Accordingly, daily low-level exposure disrupts the natural equilibrium in the endocrine system. A method enabling quantification at such products at low levels (from pg L⁻¹ to ng L⁻¹) is therefore required for these products. Surface plasmon resonance, essentially used for comprehension of molecular mechanisms and in drug discovery, can also be used for environmental pollutant monitoring. This technology has already been used for evaluation of the effects of chemical pollutants on specific nuclear receptors. It has been possible to determine the role of each individual compound on the disruption of the estrogen-activated cellular pathway. Development of SPR screening methods enables application of such an approach for quantification of these compounds in water.

Keywords: SPR; Pharmaceutical; Hormonal compounds; Detection; Water

Occurrence patterns of pharmaceuticals in water and wastewater environments by Anastasia Nikolaou; Sureyya Meric; Despo Fatta (pp. 1225-1234).

The occurrence of pharmaceuticals and their metabolites and transformation products in the environment is becoming a matter of concern, because these compounds, which may have adverse effects on living organisms, are extensively and increasingly used in human and veterinary medicine and are released continuously into the environment. A variety of pharmaceuticals have been detected in many environmental samples worldwide. Their occurrence has been reported in sewage-treatment-plant effluents, surface water, seawater, groundwater, soil, sediment and fish. This paper provides an overview of recent scientific research on the sources, occurrence, and fate of pharmaceuticals in water and wastewater.

Keywords: Pharmaceuticals; Drugs; Wastewater; Surface water; Groundwater

Fate and occurrence of X-ray contrast media in the environment by Sandra Pérez; Damià Barceló (pp. 1235-1246).

Interest in the presence of pharmaceuticals in the environment has recently increased. Despite continuous research efforts there is still a large gap in our knowledge of their fate and effects on the ecosystem. This review covers current information on the occurrence of iodinated X-ray contrast media (ICM) in the environment and developments in the analysis of these highly polar organic micropollutants in aqueous environmental samples. Findings from monitoring surveys conducted on wastewater-treatment plants (WWTP), surface waters, and drinking waters are compiled, and strategies for removal of the compounds in WWTP and waterworks using advanced treatment are reported. Characteristics and advantages of different compound-specific or element-specific mass spectrometric techniques used to monitor ICM in the environment are compared, and applications in elucidation of the structures of biotransformation products, generated in laboratory-scale experiments that simulate sewage treatment or river water/sediment systems, are described.

Keywords: Iodinated X-ray contrast media; Tandem mass spectrometry; Fate; Biodegradation; Sorption; Ozonation; Photodegradation

Liquid chromatography–tandem mass spectrometry of bioactive pharmaceutical compounds in the aquatic environment—a decade’s activities by Chunyan Hao; Ray Clement; Paul Yang (pp. 1247-1257).

The occurrence of bioactive pharmaceutical compounds in the aquatic environment is an emerging concern. Liquid chromatography, coupled with mass spectrometry (LC–MS) or tandem mass spectrometry (LC–MS–MS) using an electrospray ionization interface, is a crucial tool for addressing this issue. We review in this manuscript LC–MS and LC–MS–MS studies on waterborne PhACs in the last decade, including research activity in different geographical areas and the current status of the technology used for sample preparation, chromatographic separation, and mass spectrometric detection. A detailed overview on quality-control and quality-assurance (QC/QA) procedures is also presented, with emphasis on the need for a concerted approach to determine the numerical values associated with detection limits, and the use of low-level data qualifiers.

Keywords: Review; Pharmaceutically active compounds (PhACs); Sample preparation; Solid-phase extraction; LC–MS; LC–MS–MS; QC/QA; Low level data reporting qualifier

Human and environmental risk assessment of pharmaceuticals: differences, similarities, lessons from toxicology by J. L. C. M. Dorne; L. Skinner; G. K. Frampton; D. J. Spurgeon; A. M. J. Ragas (pp. 1259-1268).

The presence of human and veterinary pharmaceuticals in the environment has caused increasing concern due their effects on ecological receptors. Improving the risk assessment of these compounds necessitates a quantitative understanding of their metabolism and elimination in the target organism (toxicokinetics), particularly via the ubiquitous cytochrome P-450 (CYP) system and their mechanisms of toxicity (toxicodynamics). This review focuses on a number of pharmaceuticals and veterinary medicines of environmental concern, and the differences and similarities between ecological and human risk assessment. CYP metabolism is discussed with particular reference to its ubiquity in species of ecological relevance. The important issue of pharmaceutical mixtures is discussed to assess how emerging technologies such as ecotoxicogenomics may assist in moving towards a more mechanism-based environmental risk assessment of pharmaceuticals.

Keywords: Ecological risk assessment; Human risk assessment; Cytochrome P-450; Toxicokinetics; Toxicodynamics; Uncertainty factors; Ecotoxicogenomics

LC-MS analysis and environmental risk of lipid regulators by M. D. Hernando; A. Agüera; A. R. Fernández-Alba (pp. 1269-1285).

This article presents a review of liquid chromatography-mass spectrometric (LC-MS) methods applied to the determination of lipid-regulating agents, “fibrate” and “statin” classes, and some of their metabolites (clofibric acid and fenofibric acid) in environmental samples. Concentration levels of this therapeutical group have been reported in the ppt to ppb range for different compartments (wastewater, surface water and sediments) in several monitoring studies. Part of this article is dedicated to hazard assessment of lipid-regulating agents according to the approaches of the European Union (EU) and Environmental Protection Agency (EPA) for identifying persistent, bioaccumulable and toxic (PBT) substances. The pharmacodynamic and pharmacokinetic activities of these pharmaceuticals are well known and, based on this information, the derivation of the potential long-term effects, which may be induced on eco-organisms at low concentration levels, is discussed. Studies of environmental risk assessment (ERA) for lipid regulators carried out through the framework of the European Agency for the Evaluation of Medicinal Products (EMEA) and Food and Drug Administration (FDA) are presented.

Keywords: Lipid regulators; Metabolites; LC-MS; PBT; ERA

Fluoroquinolones in soil—risks and challenges by Yolanda Picó; Vicente Andreu (pp. 1287-1299).

Fluoroquinolones (FQs) are among the most important antibacterial agents used in human and veterinary medicine. Because of the growing practice of adding manure and sewage sludge to agricultural fields these drugs end up in soils, where they can accumulate and have adverse effects on organisms. This paper presents an overview of recent developments in the determination of FQs in solid environmental matrices and describes the risks and challenges (persistence, fate, effects, and remediation) which result from their presence in soil. Figure Pathways into the environment for FQs

Keywords: Antibiotics; Fluoroquinolones (FQs); Soil; Analysis; Environmental fate

Quantification of human and veterinary antibiotics in water and sediment using SPE/LC/MS/MS by Sung-Chul Kim; Kenneth Carlson (pp. 1301-1315).

An analytical method was developed and tested for four different groups of veterinary antibiotics in both river water and sediment matrices. Solid phase extraction (SPE) was used to enrich and to clean up the aqueous sample. Also, Mcllvaine and ammonium hydroxide buffer solutions were used to extract the compounds from the sediment matrix. High performance liquid chromatography (HPLC) equipped with tandem mass spectrometry (MS/MS) was used to separate and quantify the samples. The range of recoveries (in percent) for tetracyclines (TCs), sulfonamides (SAs), macrolides (MLs), and ionophore polyethers (IPs) in the water matrix were 102.2–124.8, 76.6–124.3, 89.5–114.7, 82.7–117.5 with 1–13 (%) of relative standard deviation respectively with three different concentrations. For sediment, the percent recovery ranges were 32.8–114.8, 62.4–108.9, 53.4–128.4 and 51.3–105.4 for TCs, SAs, MLs and IPs, respectively. The relative standard deviation ranged from 16 – 27 (%) over three different concentrations. The limit of quantification (LOQ) was determined by two different methods and calculated to be in the range of 0.01–0.04 μg/l and 0.3–2.5 μg/kg for TCs, SAs, and MLs in water and sediment, respectively. For IPs, the LOQ was 0.001–0.003 μg/l in river water and 0.4–3.6 μg/kg for sediment. The sediment concentration measured in an agriculture-influenced river was much higher than in the overlying water matrix, indicating a high degree of sediment partitioning for these compounds.

Keywords: Sediment; Human and veterinary antibiotics; SPE-HPLC/MS/MS

Determination of pharmaceuticals from different therapeutic classes in wastewaters by liquid chromatography–electrospray ionization–tandem mass spectrometry by Eleni Botitsi; Charalampia Frosyni; Despina Tsipi (pp. 1317-1327).

A sensitive analytical method has been developed and validated for simultaneous determination of pharmaceuticals from different therapeutic classes, i.e. five sulfonamide (SA) and trimethoprim antimicrobials and the anti-inflammatory drug diclofenac, in effluent wastewaters at trace levels. Effluent samples from treatment of wastewater were enriched by solid-phase extraction (SPE) using the Waters Oasis HLB cartridge. The analytes were identified and quantified by reversed-phase liquid chromatography–tandem mass spectrometry operated in the selected reaction monitoring (SRM) mode, using positive electrospray ionization. The pharmaceuticals were, consequently, quantified both by use of isotopically labelled internal standards and by standard addition methods to address the issue of matrix effects related to signal suppression by co-eluting compounds. Average recoveries from fortified samples were usually >70%, with relative standard deviations below 20%. Method detection limits in wastewater matrices were between 7.0 and 10 ng L⁻¹. Identification points (IPs) were used for unequivocal identification of target analytes in real samples. Diclofenac, trimethoprim, and sulfamethoxazole were mainly detected, in the concentration range 10 to 400 ng L⁻¹, in effluent samples collected from four different sewage-treatment plants in Greece.

Keywords: Liquid chromatography tandem mass spectrometry; Pharmaceuticals; Environmental analysis; Wastewater; SPE

Analytical procedure for determination of the time profile of eprinomectin excretion in sheep faeces by Nevenka Kožuh Eržen; Lena Hodošček; Vesna Cerkvenik-Flajs (pp. 1329-1335).

An analytical procedure has been introduced to enable study of the time profile of eprinomectin excretion in sheep faeces. Eprinomectin was extracted from sheep faeces with acetonitrile, the extract was cleaned by solid-phase extraction (SPE), and, after derivatization by reaction with N-methylimidazole, trifluoroacetic anhydride, and acetic acid, eprinomectin was analysed by high-performance liquid chromatography (HPLC) with fluorescence detection. The method has a low detection limit (1.0 ng g⁻¹ of moist sheep faeces), a low quantification limit (2.5 ng g⁻¹ of moist sheep faeces), good recovery (in the range 78.8 to 87.1%), and good reproducibility (RSD<10%). The method was used to study the time-profile of excretion of eprinomectin in sheep faeces after a single topical administration of 0.5 mg kg⁻¹ b.w. of the drug. Because of its good recovery, precision, and sensitivity, the method has also proved applicable to further ecotoxicological studies of eprinomectin. Figure Autochthonous Slovenian dairy breed sheep – Istrian Pramenka

Keywords: Veterinary pharmaceuticals; Eprinomectin; Analysis; Sheep faeces; Excretion

Determination of NSAIDs in river sediment samples by Jan Antonić; Ester Heath (pp. 1337-1342).

Consumption of non-steroidal anti-inflammatory drugs (NSAIDs) is increasing and with it the danger of environmental pollution by pharmaceutical residues. Publications regarding NSAIDs in the environment not only show that they are toxic to many animal species, but also highlight the need for robust analytical methods for monitoring the level of such contaminants in environmental matrices. In our study we selected the four most widely used NSAIDs in Slovenia and Central Europe, ibuprofen, naproxen, ketoprofen and diclofenac, and studied their extraction from sediment samples. We examined several extraction techniques (ultrasonic extraction, Soxhlet extraction, pressurized liquid extraction, supercritical fluid extraction and microwave-assisted extraction) using a spiked sediment sample and determined optimal extraction conditions. After extraction we applied a clean-up step, derivatisation of the analytes and gas chromatography with mass spectrometric detection (GC-MSD) and selected the most appropriate extraction procedure. The optimised analytical method chosen for analysis of sediment samples consisted of microwave-assisted extraction, clean-up of the extract with SPE, derivatisation with MSTFA and determination with GC-MSD. The optimised procedure was applied to the analysis of two environmental river samples taken from the vicinity of Novo mesto, the biggest town in the south eastern part of Slovenia with 62,000 inhabitants, a hospital and a pharmaceutical factory in its vicinity. While analysis of the sample taken upstream of the town showed no detectable amounts of NSAIDs, analysis of samples taken downstream showed quantifiable levels of two of the studied NSAIDs (naproxen and ketoprofen). Besides these two NSAIDs, river water samples sampled at the same time and location on the River Krka also showed the presence of diclofenac. Sampling on the River Krka and other Slovene rivers will in the future be repeated at different sampling points in order to track down the main sources of pollution.

Keywords: NSAIDs; Sediment; Gas chromatography-mass spectrometry; Pharmaceutical residues; Environmental pollution

Determination of UV filters and antimicrobial agents in environmental water samples by Petra Cuderman; Ester Heath (pp. 1343-1350).

Although there is increasing concern about residues from personal care products entering the aquatic environment and their potential to accumulate to levels that pose a health threat to humans and wildlife, we still know little about the extent and magnitude of their presence in the aquatic environment. In this study we describe a procedure for isolation, and subsequent determination, of compounds commonly added to personal care products. The compounds of interest include UV filters with the commercial name Eusolex (homosalate, 4-methylbenzylidenecamphor, benzophenone-3, octocrylene, butylmethoxydibenzoylmethane, ethylhexyl methoxycinnamate) and two common anti-microbial agents, clorophene and triclosan. Water samples were filtered, acidified, and extracted by use of solid-phase extraction. Extracted compounds were then derivatised before analysis by gas chromatography–mass spectroscopy. By use of our method we obtained limits of detection of 13–266 ng L⁻¹ for UV filters, and 10–186 ng L⁻¹ for triclosan and clorophene. Recoveries were 82–98% for deionised water and 50–98% for natural water (seawater, pool water, lake water, and river water). Samples collected in Slovenia included seventeen recreational waters (seawater, pool water, lake water, and river water; August 2004) and four wastewaters (January 2005). The most abundant UV filter was benzophenone-3 (11–400 ng L⁻¹). Of the two anti-microbial agents studied, trace amounts, only, of triclosan were present in the river Kolpa (68 ng L⁻¹) and in an hospital effluent (122 ng L⁻¹).

Keywords: UV filters; Antimicrobial agents; Solid-phase extraction (SPE); GC–MSD; Water

Novel approaches to the analysis of steroid estrogens in river sediments by Kateřina Hájková; Jana Pulkrabová; Jakub Schůrek; Jana Hajšlová; Jan Poustka; Michaela Nápravníková; Vladimír Kocourek (pp. 1351-1363).

A wide range of estrogenic contaminants has been detected in the aquatic environment. Among these, natural and synthetic steroid estrogens, typically present in municipal sewage-treatment plant (STP) effluents, are the most potent. In this study a new GC–MS method has been developed for direct analysis of five major steroid estrogens (estrone, 17β-estradiol, 17α-ethinylestradiol, dienestrol, and diethylstilbestrol) in river sediments. Four GC–MS systems used for analysis of underivatized analytes in purified extracts were compared. Relatively low detection limits (1.5–5 ng g⁻¹ dried sediment) and good repeatability of GC splitless injection (RSD 1–2%) were achieved by use of a system combining low-pressure gas chromatography with a single-quadrupole mass analyzer (LP-GC–MS). Use of orthogonal gas chromatography (GC×GC) hyphenated with high-speed time-of-flight mass spectrometry (HSTOF-MS) enabled not only significantly better resolution of target analytes, and their unequivocal identification, but also further improvement (decrease) of their detection limits. In addition to these outcomes, use of this unique GC×GC–TOF-MS system enabled identification of several other non-target chemicals, including pharmaceutical steroids, present in purified sediment extracts.

Keywords: Pharmaceuticals; Steroid estrogens; Contaminants; Sediment; GC/MS; Non-target screening

Analysis of pharmaceuticals in wastewater and removal using a membrane bioreactor by Jelena Radjenovic; Mira Petrovic; Damiá Barceló (pp. 1365-1377).

Much attention has recently been devoted to the life and behaviour of pharmaceuticals in the water cycle. In this study the behaviour of several pharmaceutical products in different therapeutic categories (analgesics and anti-inflammatory drugs, lipid regulators, antibiotics, etc.) was monitored during treatment of wastewater in a laboratory-scale membrane bioreactor (MBR). The results were compared with removal in a conventional activated-sludge (CAS) process in a wastewater-treatment facility. The performance of an MBR was monitored for approximately two months to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of target compounds. Pharmaceuticals were, in general, removed to a greater extent by the MBR integrated system than during the CAS process. For most of the compounds investigated the performance of MBR treatment was better (removal rates >80%) and effluent concentrations of, e.g., diclofenac, ketoprofen, ranitidine, gemfibrozil, bezafibrate, pravastatin, and ofloxacin were steadier than for the conventional system. Occasionally removal efficiency was very similar, and high, for both treatments (e.g. for ibuprofen, naproxen, acetaminophen, paroxetine, and hydrochlorothiazide). The antiepileptic drug carbamazepine was the most persistent pharmaceutical and it passed through both the MBR and CAS systems untransformed. Because there was no washout of biomass from the reactor, high-quality effluent in terms of chemical oxygen demand (COD), ammonium content (N-NH₄), total suspended solids (TSS), and total organic carbon (TOC) was obtained.

Keywords: Wastewater treatment; Membrane bioreactor; Conventional activated sludge treatment; Pharmaceuticals; Removal efficiency

Removal of pharmaceutical residues in a pilot wastewater treatment plant by Tina Kosjek; Ester Heath; Boris Kompare (pp. 1379-1387).

Concern is growing over the contamination of the environment with pharmaceutical residues, among which non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most abundant groups. Their widespread appearance in the aquatic environment is because of their high consumption and their incomplete removal during wastewater treatment. Because effective operation of wastewater-treatment plants is important for minimising the release of xenobiotic compounds, for example pharmaceutical products, into the aquatic environment, our study focuses on removal of commonly used NSAIDs (ibuprofen, naproxen, ketoprofen, diclofenac) and clofibric acid in a specially designed small-scale pilot wastewater treatment plant (PWWTP). This study shows that, except for diclofenac, steady-rate removal of NSAIDs over a two-year monitoring period has been achieved. Elimination of the compounds in the PWWTP was ≥87% for ibuprofen, naproxen and ketoprofen but only 49–59% for diclofenac. We also studied clofibric acid. Results after one month of operation revealed 30% elimination with no sign of adaptation by the biomass. Also described are degradation products of diclofenac, which we were able to identify because of the similarity of their mass spectra with those in the NIST library and by comparing the retention times of different compounds. Although the structures of these compounds were confirmed with a high probability (99%), we still need to compare the fragmentation of authentic compounds with degradation products formed under our experimental conditions. Degradation products of ibuprofen, naproxen, ketoprofen, and clofibric acid were found but these must be identified by use of high-resolution mass spectrometry and analysis of authentic compounds.

Keywords: Pilot wastewater treatment plant; Ibuprofen; Ketoprofen; Naproxen; Diclofenac; Degradation products

Phytotoxicity assessment of diclofenac and its phototransformation products by Mechthild Schmitt-Jansen; Peter Bartels; Nicole Adler; Rolf Altenburger (pp. 1389-1396).

The occurrence of pharmaceuticals in the environment is an emerging issue. Several studies observed that the non-steroidal anti-inflammatory drug diclofenac is ubiquitously present in most of the surveyed surface waters, worldwide. Phototransformation of diclofenac was reported from laboratory assays as well as in natural water systems, raising the question of possible adverse effects of the phototransformation products of diclofenac to aquatic organisms. In this study the phytotoxicity of diclofenac exposed to natural sunlight was evaluated using synchronized cultures of the unicellular chlorophyte Scenedesmus vacuolatus. Diclofenac dissolved in ultra-pure water at 50 mg L⁻¹ was exposed to natural midsummer sunlight for a maximum of 145 h. Twice a day subsamples were taken for chromatography and parallel phytotoxicity assessment. Inhibition of algal reproduction of the initial diclofenac solution was in the mg L⁻¹ range indicating no specific toxicity of diclofenac towards S. vacuolatus. Fast degradation of diclofenac was observed with half lives between 3.3 and 6.4 h during the first and the third day of exposure, respectively. Phytotoxicity increased after 3.5 h of exposure of diclofenac to sunlight and showed a maximum of sixfold enhanced toxicity after 53 h of exposure to sunlight. Several phototransformation products were found during the experiment. The time courses of the relative concentration of three transformation products significantly correlated with enhanced phytotoxicity during the experiment. This indicates a high toxicity potential of phototransformation products of diclofenac at concentration levels that may come close to environmental concentrations of residual diclofenac after degradation. We conclude that toxicity assessment of phototransformation products should be included in the risk assessment of pharmaceuticals in the environment.

Keywords: Pharmaceuticals; Periphyton; S. vacuolatus ; UV radiation; Environmental risk assessment

The chick embryo: an animal model for detection of the effects of hormonal compounds by Sandrine Biau; Sandrine Bayle; Pascal de Santa Barbara; Benoit Roig (pp. 1397-1403).

Hormonal compounds are a class of pharmaceutical product that disrupt the endocrine system of animals and humans. Exposure to these molecules, even at low concentrations, can have severely damaging effects on the environment, to organisms, and to humans. The cumulative presence of these compounds is also characterized by synergistic effects which are difficult to estimate. They are an underestimated danger to the environment and to the human population. This paper presents an in-vivo model enabling to assessment of the real impact of exposure to hormonal compounds and the synergistic effect which can be involved. The anatomical effects of in-ovo exposure to two natural estrogen compounds (estrone and estriol, at 600 ng g⁻¹) and a synthetic estrogen (ethynylestradiol, at 20 ng g⁻¹) have been investigated. Estrone and estriol lead to morphological defects, mainly in the urogenital system of the developing chick embryo, whereas ethynylestradiol has fewer effects. Estriol caused persistence of Müllerian ducts in 50% of male embryos and hypertrophic oviducts in 71% of females. Estrone had the same effects but at the percentages were lower. Kidney dysfunction was also observed, but only with estrone, in both males and females. We also tested estrogenic compounds in two types of cell line which are estrogen sensitive (BG1 and MCF7) then completed and confirmed our previous in-vivo results. Seven pharmaceutical-like compounds—estrone (E1), estradiol (E2), estriol (E3), ethynylestradiol (EE₂), carbamazepine (C), genistein (G), and bisphenol-A (BPA)—were tested alone or in mixtures. Different effects on the two cell lines were observed, indicating that endocrine compounds can act differently on this organism. Experiments also showed that these molecules have synergistic action and induce more severe effects when they are in mixtures.

Keywords: Estrogenic compound; Synergy; Animal model; Chick embryo; Human

Ultrastructural effects of pharmaceuticals (carbamazepine, clofibric acid, metoprolol, diclofenac) in rainbow trout (Oncorhynchus mykiss) and common carp (Cyprinus carpio) by R. Triebskorn; H. Casper; V. Scheil; J. Schwaiger (pp. 1405-1416).

In order to assess potential effects of human pharmaceuticals in aquatic wildlife, laboratory experiments were conducted with carbamazepine, clofibric acid, metoprolol, and diclofenac using fish as test organisms. For each substance, at least one environmentally relevant concentration was tested. In liver, kidney, and gills of trout and carp exposed to carbamazepine, clofibric acid, and metoprolol, ultrastructural effects were qualitatively described and semi-quantitatively assessed. The obtained assessment values were compared with previously published data for diclofenac-induced effects in rainbow trout tissues. Quantitative analyses of protein accumulated in kidneys of diclofenac-exposed trout corroborated previously published data which indicated that diclofenac induced a severe glomerulonephritis resulting in a hyaline droplet degeneration of proximal kidney tubules. The investigations provided information on the general health status of the pharmaceutical-exposed fish, and allowed a differential diagnosis of harmful effects caused by these human pharmaceuticals in non-target species. For the different cytological effects observed, lowest observed effect concentration (LOECs) for at least three of the test substances (diclofenac, carbamazepine, metoprolol) were in the range of environmentally relevant concentrations (1 μg/L).

Keywords: Pharmaceuticals; Liver; Gills; Kidney; Trout; Carp

Silicone rod extraction of pharmaceuticals from water by Albrecht Paschke; Janine Brümmer; Gerrit Schüürmann (pp. 1417-1421).

Silicone elastomer (in the form of a flexible rod) is one of the materials currently tested for use in analytical extraction techniques and passive sampling devices. We investigated the applicability of this material for the enrichment of selected polar pharmaceuticals (antipyrine, carbamazepine, diclofenac, ibuprofen, bezafibrate) from water. Time-resolved batch extraction tests (up to five weeks in duration) were performed in stirred water samples (∼0.5 L) with 2-cm-long silicone rod pieces. After re-extraction of trapped compounds with methanol, analysis was performed using liquid chromatography coupled with mass spectrometry. Distribution equilibrium was reached after a test duration of seven days. The silicone rod/water partition coefficients of the investigated pharmaceuticals range from 4 (antipyrine) to 1250 (diclofenac), and are related to the hydrophobicity of the compound. Enrichment of these pharmaceuticals in the silicone rod is lower than for other compound classes (chlorinated and polycyclic hydrocarbons). Figure Batch extraction of pharmaceuticals from a water sample (in an Erlenmeyer flask with a magnetic stirrer) using two silicone rods

Keywords: Pharmaceuticals; Water; Sample preparation; Solid-phase microextraction; Silicone rod

Monitoring surface water pollutants by Damià Barceló (pp. 1423-1423).

is full Research Professor at IIQAB-CSIC and Head of the Environmental Chemistry Department. His scientific focus is on method development and monitoring, and the fate of priority, new, and emerging pollutants, including endocrine-disrupting compounds, using GC and LC coupled with advanced tandem and hybrid mass spectrometric analysis, in combination with bioassays and biosensors, and studies of the effects of endocrine-disrupting compounds.

Monitoring the effect of chemicals on biological communities. The biofilm as an interface by Sergi Sabater; Helena Guasch; Marta Ricart; Anna Romaní; Gemma Vidal; Christina Klünder; Mechthild Schmitt-Jansen (pp. 1425-1434).

Biofilms can be regarded as early warning systems for detection of the effects of toxicants on aquatic systems, because they have been successfully used for detection of other environmental stressors (e.g. pH, salinity, organic pollution). A variety of methods is used for detection of the effects of toxicants by use of biofilms. The methods range from structurally-based to functionally-based, and from in vitro-based to systemic approaches. Physiological approaches may be appropriate for detection of acute effects. Among these methods, photosynthesis is more related to the effect of toxicants affecting algal communities, directly or indirectly, and extracellular enzyme activity is less specific. Selecting one or the other may depend on the suspected direct effect of the toxicant. Integrated studies have revealed the relevance of toxicants to top-down or bottom-up regulation of the biofilm community. Persistent or chronic effects should affect other biofilm indicators, for example growth or biomass-related factors (e.g. chlorophyll), or community composition. Among these, community composition might better reflect the effects of the toxicant(s), because this may cause a shift from a sensitive to a progressively tolerant community. Community composition-based approaches do not usually adequately reflect cause–effect relationships and require complementary analysis of properties affected in the short-term, for example physiological properties. The current array of methods available must be wisely combined to disentangle the effects of chemicals on biofilms, and whether these effects are transient or persistent, to successfully translate the chemical action of toxicants into the effect they might have on the river ecosystem.

Keywords: Biofilm; Communities; Heavy metals; Organic pollutants; Stream

How can immunochemical methods contribute to the implementation of the Water Framework Directive? by Petra M. Krämer; Dieter Martens; Stephan Forster; Ildi Ipolyi; Claudia Brunori; Roberto Morabito (pp. 1435-1448).

Immunochemical methods (in particular immunoassays) have been applied to spring and surface water samples, respectively, which were set-up as reference materials (RM) within two proficiency testing campaigns. For the first set of proficiency tests (PTs) described here (which were actually the second round of PTs organized, spring 2005), three ELISAs (enzyme-linked immunosorbent assays) were employed in the enzyme tracer format for isoproturon, diuron, and atrazine, respectively. Results were evaluated in comparison with conventional reference methods (LC, GC). Based on their Z-score laboratory performances, the results for isoproturon and diuron were satisfactory, both for fortified spring water and for the blind solution. The results for atrazine were strongly influenced by other triazines present and needed detailed interpretation. For the second set of PTs described here (which were actually the third round of PTs organized, spring 2006), two ELISAs in the coating antigen format were used for isoproturon and diuron, and the result was included with the results obtained by conventional methods during the PTs. The results (the Z-scores) for isoproturon were again classified as satisfactory, in both fortified surface water and blind solution. The results for diuron in ELISA showed an influence of the water matrix, while the analysis of the blind solution was satisfactory. In addition, an ELISA in the enzyme tracer format was applied to analyze isoproturon, diuron, and atrazine in surface water samples, which had been set-up and spiked during a field trial (tank experiment) at the Maas River at Eijsden, The Netherlands. The immunoassay results were compared with those from an in-house on-line SPE LC/MS–MS used as reference. Although the immunochemical results were sometimes higher than those determined in the reference analysis, the general concentration trends in the samples were similar. The contribution of immunochemical methods to the implementation of the European Water Framework Directive is also discussed.

Keywords: Proficiency testing; Pesticides; Water; Immunoassay; Microtiter plate

Multi-analyte SPR immunoassays for environmental biosensing of pesticides by E. Mauriz; A. Calle; J. J. Manclús; A. Montoya; L. M. Lechuga (pp. 1449-1458).

Multi-analyte detection of environmentally relevant pesticides is performed by using a two-channelled surface plasmon resonance (SPR) biosensor. The special design of the SPR instrument allows the determination of several analytes (DDT, chlorpyrifos and carbaryl) via different immobilization formats. First, simultaneous pesticide monitoring is possible by flowing chlorpyrifos, carbaryl or DDT samples separately over each channel of the SPR system, wherein their corresponding recognition element was previously immobilized. The second approach is based on the multiple and combined immobilization of several analyte recognition elements on the sensing surface of one individual flow cell. In this format, the analysis time for all three pesticides varied from 40 to 60 min depending on the number of regeneration cycles. In most cases, similar detection limits were attained for the target analyte irrespective of the assay format, with sensitivity values at the nanogram per litre level (18–50 ng L⁻¹). The assay reproducibility was proved through the repeated use of the same sensor surface for over more than 200 assay cycles, whereas the absence of biosensor response to non-related analytes showed the specificity and reliability of the analysis. The SPR instrument, including optics, electronics and microfluidics, is already commercialised by the company SENSIA, SL.

Keywords: DDT; Chlorpyrifos; Carbaryl; SPR immunosensor; Multi-detection; On-line determination; Environmental monitoring

Assessment of priority pesticides, degradation products, and pesticide adjuvants in groundwaters and top soils from agricultural areas of the Ebro river basin by Alain Hildebrandt; Sílvia Lacorte; Damià Barceló (pp. 1459-1468).

Gas chromatography-mass spectrometry (GC/MS) was employed for the determination of 30 widely used pesticides including various transformation products and alkylphenols in water and agricultural soils with the aim of assessing the impact of these compounds in agricultural soils and the underlying aquifer. The extraction, clean-up, and analytical procedures were optimized for both water and soil samples to provide a highly robust method capable of determining target analytes at the ppb–ppt level with high precision. For water samples, different solid-phase extraction cartridges and conditions were optimized; similarly, pressurized liquid extraction conditions were tested to provide interference-free extracts and high sensitivity. Instrumental LODs of 3–4 pg were obtained. The multi-residue extraction procedures were applied to the analysis of groundwaters and agricultural soils from the Ebro river basin (NE Spain). Most ubiquitous herbicides detected were triazines but some acetanilides and organophosphorus pesticides were also found; the pesticide additive tributylphosphate was found in all water samples. Levels varied between 0.57 and 5.37 μg/L in groundwater, whereas nonylphenol was the sole compound detected in soil. Alkylphenols are used as adjuvants in pesticide formulations and are present in sludges employed as soil fertilizers. Occurrence was found to be similar to other environmental studies.

Keywords: Pesticides; Water; Soil; Environment; GC-MS; Extraction (SPE/PLE)

Polar herbicides, pharmaceutical products, perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and nonylphenol and its carboxylates and ethoxylates in surface and tap waters around Lake Maggiore in Northern Italy by Robert Loos; Jan Wollgast; Tania Huber; Georg Hanke (pp. 1469-1478).

A survey of contamination of surface and drinking waters around Lake Maggiore in Northern Italy with polar anthropogenic environmental pollutants has been conducted. The target analytes were polar herbicides, pharmaceuticals (including antibiotics), steroid estrogens, perfluorooctanesulfonate (PFOS), perfluoroalkyl carboxylates (including perfluorooctanoate PFOA), nonylphenol and its carboxylates and ethoxylates (NPEO surfactants), and triclosan, a bactericide used in personal-care products. Analysis of water samples was performed by solid-phase extraction (SPE) then liquid chromatography–triple-quadrupole (tandem) mass spectrometry (LC–MS–MS). By extraction of 1-L water samples and concentration of the extract to 100 μL, method detection limits (MDLs) as low as 0.05–0.1 ng L⁻¹ were achieved for most compounds. Lake-water samples from seven different locations in the Southern part of Lake Maggiore and eleven samples from different tributary rivers and creeks were investigated. Rain water was also analyzed to investigate atmospheric input of the contaminants. Compounds regularly detected at very low concentrations in the lake water included: caffeine (max. concentration 124 ng L⁻¹), the herbicides terbutylazine (7 ng L⁻¹), atrazine (5 ng L⁻¹), simazine (16 ng L⁻¹), diuron (11 ng L⁻¹), and atrazine-desethyl (11 ng L⁻¹), the pharmaceuticals carbamazepine (9 ng L⁻¹), sulfamethoxazole (10 ng L⁻¹), gemfibrozil (1.7 ng L⁻¹), and benzafibrate (1.2 ng L⁻¹), the surfactant metabolite nonylphenol (15 ng L⁻¹), its carboxylates (NPE₁C 120 ng L⁻¹, NPE₂C 7 ng L⁻¹, NPE₃C 15 ng L⁻¹) and ethoxylates (NPE nOs, n = 3-17; 300 ng L⁻¹), perfluorinated surfactants (PFOS 9 ng L⁻¹, PFOA 3 ng L⁻¹), and estrone (0.4 ng L⁻¹). Levels of these compounds in drinking water produced from Lake Maggiore were almost identical with those found in the lake itself, revealing the poor performance of sand filtration and chlorination applied by the local waterworks.

Keywords: Polar herbicides; Pharmaceuticals; Perfluorooctanesulfonate (PFOS); Nonylphenol; Drinking water; Solid-phase extraction; Liquid chromatography–tandem mass spectrometry (LC–MS–MS)

Use of chemometric and geostatistical methods to evaluate pesticide pollution in the irrigation and drainage channels of the Ebro river delta during the rice-growing season by Marta Terrado; Marina Kuster; Demetrio Raldúa; Miren Lopez de Alda; Damià Barceló; Romà Tauler (pp. 1479-1488).

Data sets obtained from quantitative analysis of seventeen pesticides in water samples from a network of irrigation and drainage channels in the Ebro river delta (Catalonia, NE Spain) have been analysed by chemometric and geostatistical methods. Samples were taken at fourteen locations during the main rice-growing season, from May to August 2005. Principal-component analysis enabled investigation of the spatial and temporal distribution of the main pollution patterns caused by application of pesticides in the region under study. A first pesticide-contamination pattern from the Ebro river was differentiated from a second more specific pattern from the water-drainage channels of the delta, collected from the rice fields. The seasonal peak in this more specific rice pesticide source was observed in July. Coupling the results from chemometric data analysis with use of geostatistical methods was shown to be a useful procedure for discovery of the most significant spatial and monthly variations of the main pesticide-contamination patterns, taking into account the particular geographical structure of the area under study.

Keywords: Pesticides; Chemometrics; PCA; GIS; Ebro river delta

Extending the dynamic range of electrochemical sensors using multiple modified electrodes by Edith Chow; Elicia L. S. Wong; Owen Pascoe; D. Brynn Hibbert; J. Justin Gooding (pp. 1489-1498).

Multiple electrodes, combined with a chemometric strategy to calibrate the measurement response, have been used for the determination of an analyte across a broader dynamic range than is possible with a single electrode. The model system used for the detection of copper comprised electrodes modified with a self-assembled monolayer. The electrodes were modified with the copper-complexing species (3-mercaptopropionic acid, thioctic acid, and the peptides cysteine and Gly-Gly-His) and copper was determined over concentrations ranging from nanomolar to millimolar using voltammetric analysis. We have demonstrated that by combining the calibration functions from the four electrodes a better estimate (i.e. with smaller variance) of the concentration of the analyte is obtained. Measurement uncertainty is expressed for independently prepared electrodes, which allows the possibility of commercial production and factory calibration. The principles of using multiple electrodes modified with recognition elements with different affinities for the target analyte to extend the dynamic range of sensors is a general one that could be applied to other analytes.

Keywords: Metal detection; Peptides; Biosensors; Electrochemistry; Electrode arrays

Application of support vector machines to ¹H NMR data of fish oils: methodology for the confirmation of wild and farmed salmon and their origins by Saeed Masoum; Christophe Malabat; Mehdi Jalali-Heravi; Claude Guillou; Serge Rezzi; Douglas Neil Rutledge (pp. 1499-1510).

Support vector machines (SVMs) were used as a novel learning machine in the authentication of the origin of salmon. SVMs have the advantage of relying on a well-developed theory and have already proved to be successful in a number of practical applications. This paper provides a new and effective method for the discrimination between wild and farm salmon and eliminates the possibility of fraud through misrepresentation of the country of origin of salmon. The method requires a very simple sample preparation of the fish oils extracted from the white muscle of salmon samples. ¹H NMR spectroscopic analysis provides data that is very informative for analysing the fatty acid constituents of the fish oils. The SVM has been able to distinguish correctly between the wild and farmed salmon; however ca. 5% of the country of origins were misclassified.

Keywords: Support vector machines (SVMs); Salmon; Authenticity; NMR; Correlation optimized warping (COW)

Determination of nitrobenzene by differential pulse voltammetry and its application in wastewater analysis by Huan-kun Zhang; Shu-xuan Liang; Shi-jiang Liu (pp. 1511-1516).

A new method for the determination of nitrobenzene (NB) by differential pulse voltammetry (DPV) based on an adsorptive stripping technique was developed. Cyclic voltammetry (CV) was used in a comparative investigation into the electrochemical reduction of NB at a glassy carbon electrode (GCE). With this electrode, the sharp peak of NB appeared at −0.71 V (vs. Ag/AgCl). The experimental parameters were optimized. Studies on the effect of pH on the peak height and peak potential were carried out over the pH range ca. 9.0–11.5 with sodium carbonate/sodium hydrogen carbonate buffer solution. A solution of pH 9.9 was chosen as analytical medium. Cathodic peak currents were found to be linearly related to the concentration of NB over the range ca. 12.3–1.23 × 10⁴ μg L⁻¹ with relative standard deviations of ca. 3.26–6.75%. The detection limit of NB in water was 5.42 μg L⁻¹. The interference of organic and inorganic species on the voltammetric response was also studied. The proposed method was applied to the determination of NB in wastewater samples with an average recovery of ca. 95.9–102.4%.

Keywords: Determination; Glassy carbon electrode; Differential pulse voltammetry; Nitrobenzene

Desorption of BTEX from activated charcoal using accelerated solvent extraction: evaluation of occupational exposures by A. Campos-Candel; M. Llobat-Estellés; A. R. Mauri-Aucejo (pp. 1517-1523).

A procedure for the determination of benzene, toluene, ethylbenzene and o-xylene, m-xylene and p-xylene (BTEX) in occupational environments is proposed. These compounds are extracted from activated charcoal using accelerated solvent extraction. Operational parameters are optimized and quantitative recovery is obtained using acetonitrile as the extraction solvent and 1-mL extraction cells, a preheat time of 2 min, a temperature of 160 °C, a pressure of 1,500 psi, a static period of 5 min, a flush volume of 110%, two cycles and a purge time of 90 s. Determination of BTEX compounds is carried out by gas chromatography using a flame ionization detector. The recoveries, obtained for a confidence level of 95%, are 91 ± 4, 100 ± 3, 104 ± 2, 93 ± 4, 99 ± 2 and 99 ± 2% for benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene, respectively. The detection limits are 0.5 μg for benzene, 0.7 μg for toluene and 1.0 μg for the other compounds. The proposed procedure has been applied to real samples collected in several workplaces, like a microbiology laboratory, an analytical chemistry laboratory, a printer’s, a car repair shop and a petrol station. From the results obtained, it can be concluded that the occupational exposures determined are always acceptable because they are lower than the tenth part of the recommended exposure limits (VLA-ED and VLA-EC).

Keywords: BTEX; Workplace; Accelerated solvent extraction

Determination of organic additives in mortars by near-IR spectroscopy. A novel approach to designing a sample set with high-variability components by Marcelo Blanco; Anna Peguero (pp. 1525-1532).

Industrial mortars consist primarily of a mixture of cement and an aggregate plus a small amount of additives that are used to modify specific properties. Using too high or too low additive rates usually results in the loss of desirable properties in the end product. This entails carefully controlling the amounts of additives added to mortar in order to ensure correct dosing and/or adequate homogeneity in the final mixture. Near-IR (NIR) spectroscopy has proved effective for this purpose as it requires no sample pretreatment and affords expeditious analyses. The purpose of this work was to determine two organic additives (viz. Ad1 and Ad2) in mortars by using partial least squares regression multivariate calibration models constructed from NIR spectroscopic data. The additives are used to expedite setting and increase cohesion between particles in the mortar. In order to ensure that the sample set contained natural variability in the samples, we used a methodology based on experimental design to construct a representative set of samples. This novel design is based on a hexagonal antiprism that encompasses the concentration ranges spanned by the analytes and the variability inherent in each additive. The D-optimality criterion was used to obtain various combinations between Ad1 and Ad2 additive classes. The partial least squares calibration models thus constructed for each additive provided accurate predictions: the intercept and the slope of the plots of predicted values versus reference values for each additive were close to 0 and 1, respectively, and their confidence ranges included the respective value. The ensuing analytical methods were validated by using an external sample set.

Keywords: Near-IR spectroscopy; Partial least squares; Hexagonal antiprism design; Mortar

Development of a novel nitrate-selective composite sensor based on doped polypyrrole by Giaan A. Álvarez-Romero; Manuel Eduardo Palomar-Pardavé; María Teresa Ramírez-Silva (pp. 1533-1541).

The manufacture and evaluation of a novel sensor built with a composite material, highly selective to nitrate ions using doped polypyrrole as a recognition agent, are presented. When the ratio of recognition agent to graphite was optimized at 1:1, and the sensitivities found closely approached nernstian behavior. The stability times attained were less than 14 min with response times also below 20 s. Batch characterization of the sensor displayed a sensitivity of 57.1 mV/decade of nitrate ion activity ( $$a_{{ ext{NO}}_3^ - }$$ ) and a detection limit of 5.37 × 10⁻⁵ M, which are comparable to those reported for commercial sensors. Evaluation of the selectivity coefficients showed high affinity to nitrate ion, superior to that of commercial sensors and others reported in the literature. The composite material gives the sensor a prolonged service life with the added capability of allowing the regeneration of its active surface. Coupling the sensor and a solid state, composite-type, reference electrode to a flow injection analysis system (FIA) permitted to achieve an effective overall assessment of the system. A nitrate determination test was conducted on real samples. A comparison of the results obtained, either with stationary measurements or with FIA, indicated that there were no significant differences from the values from manufacturer’s specifications.

Keywords: Solid-state sensors; Nitrate; Ion-selective electrodes; Flow injection; Composite materials; Tubular potentiometric system

Influence of structural factors on the enhanced activity of moxifloxacin: a fluorescence and EPR spectroscopic study by Patrícia Neves; Andreia Leite; Maria Rangel; Baltazar de Castro; Paula Gameiro (pp. 1543-1552).

Partition coefficients of moxifloxacin in liposomes of dimyristoyl-L-α-phosphatidylcholine or dimyristoyl-L-α-phosphatidylglycerol and water were determined by spectrophotometry and fluorimetry. The K _p values obtained were larger than those reported for most of the other fluoroquinolones, a consequence of the structural changes observed in the molecule of moxifloxacin, which in turn change its acid/base properties. Introduction of a methoxy group at position 8 and a diazabicyclonyl ring at position 7 in the basic fluoroquinolone structure alters the charge distribution at the physiological pH of 7.4, and these changes seem to be responsible for its improved antibacterial potency and broader spectrum of activity. Location studies have also been performed using fluorescence and electron paramagnetic resonance (EPR) spectroscopies. The results show that moxifloxacin must be located near the phospholipid headgroups, similar to other fluoroquinolones, but contributions from a hydrophobic component were also detected. These results suggest that the enhanced activity of this drug may be related to a more facilitated entrance into the bacterial cell, perhaps including a mediator step involving electrostatic interaction with a hydrophobic component; this step then controls the extent or orientation of insertion and improves the electrostatic interaction.

Keywords: Fluoroquinolones; Spectroscopic techniques; Liposomes; Electrostatic interactions

Immobilization of hemoglobin on SBA-15 applied to the electrocatalytic reduction of H₂O₂ by Yuge Liu; Qin Xu; Xiaomiao Feng; Jun-Jie Zhu; Wenhua Hou (pp. 1553-1559).

The direct electron transfer between hemoglobin (Hb) and an electrode was realized by first immobilizing the protein onto SBA-15.The results of the immobilization showed that the adsorption was pH-dependent with a maximum adsorption near the isoelectric point of the protein, and SBA-15 with a larger pore diameter showed greater adsorption capacity for Hb. UV–vis spectroscopy and nitrogen adsorption analysis indicated that Hb was adsorbed within the channel of SBA-15 and no significant denaturation occurred to the protein. The Hb/SBA-15 composite obtained was used for the fabrication of a Hb biosensor to detect hydrogen peroxide. A pair of well-defined redox peaks at −0.337 and −0.370 V on the Hb/SBA-15 composite modified glassy carbon electrode was observed, and the electrode reactions showed a surface-controlled process with a single proton transfer at a scan rate range from 20 to 1,000 mV/s. The sensor showed a fast amperometric response, a low detection limit (2.3 × 10⁻⁹ M) and good stability for the detection of H₂O₂. The electrochemical results indicated that the immobilized Hb still retained its biological activity.

Keywords: Hemoglobin; Immobilization; SBA-15; Direct electron transfer; Biosensor

Time-resolved fluoroimmunoassay for ractopamine in swine tissue by Jianzhong Shen; Zhen Zhang; Yan Yao; Weimin Shi; Yibing Liu; Suxia Zhang (pp. 1561-1564).

This study describes the development and validation of a time-resolved fluoroimmunoassay (TR-FIA) for screening ractopamine (RAC) in swine tissue. The method is based on the direct competitive-type immunoassay using europium-labeled anti-RAC monoclonal antibody as a tracer and RAC–ovalbumin as a solid-phase antigen. When RAC was spiked at levels of 1–10 μg kg⁻¹, recoveries ranged from 88.2 to 118.5% for swine liver and muscle with coefficients of variation from 7.1 to 20.5%. The detection limit was 0.1 μg kg⁻¹. The proposed TR-FIA method was applied to the determination of RAC in an actual residue study and the applicability was confirmed by liquid chromatography–tandem mass spectrometry.

Keywords: Time-resolved fluoroimmunoassay; Ractopamine; Swine tissue

Effect of silica nanoparticles with different sizes on the catalytic activity of glucose oxidase by Yingying Sun; Feng Yan; Weiwei Yang; Shuang Zhao; Wensheng Yang; Changqing Sun (pp. 1565-1572).

In this work we present a strategy for the covalent immobilization of periodate oxidized glucose oxidase ( $$ { ext{IO}}^{ - }_{4} { ext{ - GOx}} $$ ) to aminated silica nanoparticles (ASNPs) modified on gold electrodes. Silica nanoparticles greatly enhanced the catalytic ability of GOx toward the oxidation of glucose and improved the electron transfer between the GOx and the electrode surface. ASNPs of varying size—that is 100, 80, 60, and 30 nm—were prepared, and they were used to fabricate biosensors. Electrochemical impedance spectroscopy (EIS) of ferrocyanide followed the assembly process and verified the successful immobilization of $$ { ext{IO}}^{ - }_{4} { ext{ - GOx}} $$ on ASNPs modified on gold electrodes. From the analysis of catalytic signals of biosensors using different sizes of ASNPs under the same conditions, the surface concentration of electrically wired enzyme (Γ _ET) was estimated and was found to increase with decreasing ASNPs size. Therefore, the sensitivity of biosensors using smaller ASNPs was higher than that using larger particles. Specifically, we utilized the ASNPs with optimal size (30 nm) to fabricate the glucose biosensor. The resulting electrodes showed a wide linear response to glucose at least to 6 mM and reached 95% of the steady-state current in less than 4 s with a sensitivity of 5.02 μA mM⁻¹ cm⁻² and a detection limit of 0.01 mM. The biosensor also showed excellent stability and good reproducibility.

Keywords: Glucose oxidase; Aminated silica nanoparticles; Covalent attachment; Biosensors

GC–MS–MS analysis of bacterial fatty acids in heavily creosote-contaminated soil samples by M. Byss; J. Tříska; D. Elhottová (pp. 1573-1577).

Phospholipid fatty acid profiles of soil samples enable rapid and reproducible measurement and characterization of the dominant soil microbial communities. When extensive polycyclic aromatic hydrocarbon (PAH) pollution is present in the soil it is very difficult, or even impossible, to distinguish specific fatty acids in GC–MS chromatograms in full-scan mode, because of the PAHs which, because of their lipophilic character, are co-extracted with the lipids. Selected ions in the samples were scanned in MS–MS mode to eliminate the aromatic hydrocarbon signals and obtain clear chromatograms of the fatty acids. By using this technique it was possible to clearly distinguish at least eleven fatty acids in heavily creosote-contaminated soil samples (PAH concentration approximately 15 g kg⁻¹ dry weight of soil).

Keywords: GC–MS–MS; PLFA; PAH; Creosote; Soil

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Analytical and Bioanalytical Chemistry (v.387, #4)