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A simple, fast, and sensitive method is proposed for the analysis of 32 priority substances (PS) from EU Water Framework Directive (WFD) and the first Watch List in effluents of wastewater treatment plants (EWW), surface waters (SW) and drinking waters (DW). Dispersive liquid-liquid microextraction (DLLME) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) is used. For DLLME, a mixture of 1,1,2-trichloroethane as extraction solvent (75 µL) and acetonitrile as disperser solvent (3.2 mL) is proposed. The method was validated in EWW, SW and DW, showing satisfactory accuracy values ranging from 90% to 104%, good precision (relative standard deviation, RSD%, lower than 13%) and uncertainty values between 7% and 34%. Regarding sensitivity, method limits of quantification (MLOQs) of 4.8, 5.2 and 8.8 ng L−1 for DW, SW and EWW, respectively, were obtained. The developed method was applied to analyze PS in water from effluents of waste water treatment plants (WWTPs), surface water of the Llobregat River and its main tributaries (Catalonia, NE Spain) and drinking water from a Drinking Water Treatment Plant (DWTP). Moreover, the efficiency of treatment plants (DWTP, WWTP) on the elimination of PS was evaluated. Only 3 PS (lindane, terbutryn and dicofol) were detected, being terbutryn the compound found at the highest levels (up to 493 ng L−1 in EWW samples). Regarding environmental quality standard (WFD) for terbutryn in surface waters, only one sample, the Rubí stream (431 ng L−1), showed levels of terbutryn higher than maximum allowable concentration (340 ng L−1).

Pentachlorophenol (PCP) is globally dispersed and contamination of soil with this biocide adversely affects its functional biodiversity, particularly of fungi - key colonizers. Their functional role as a community is poorly understood, although a few pathways have been already elucidated in pure cultures. This constitutes here our main challenge - elucidate how fungi influence the pollutant mitigation processes in forest soils. Circumstantial evidence exists that cork oak forests in N. W. Tunisia - economically critical managed forests are likely to be contaminated with PCP, but the scientific evidence has previously been lacking. Our data illustrate significant forest contamination through the detection of undefined active sources of PCP. By solving the taxonomic diversity and the PCP-derived metabolomes of both the cultivable fungi and the fungal community, we demonstrate here that most strains (predominantly penicillia) participate in the pollutant biotic degradation. They form an array of degradation intermediates and by-products, including several hydroquinone, resorcinol and catechol derivatives, either chlorinated or not. The degradation pathway of the fungal community includes uncharacterized derivatives, e.g. tetrachloroguaiacol isomers. Our study highlights fungi key role in the mineralization and short lifetime of PCP in forest soils and provide novel tools to monitor its degradation in other fungi dominated food webs.

In this work an LC-MS/MS method has been developed for the simultaneous analysis of kasugamycin (KAS) and streptomycin (STR) in vegetable samples. The use of a mixed-mode HPLC column and a ternary mobile phase acetonitrile:water:0.5% aqueous formic acid in gradient elution mode are proposed to provide enough retention and resolution for these highly polar compounds. Heated-electrospray ionization (H-ESI) has been used to ionize KAS and STR when coupling liquid chromatography to mass spectrometry. In contrast to what happens with most aminoglycosides, KAS only showed singly charged ions in the full-scan mass spectrum. The [M + H]+ of both KAS and STR are proposed as precursor ions for tandem mass spectrometry since more stable product ions and better ion ratio precisions are obtained. Fragmentation of KAS has been studied, showing that the cleavage of the glycosidic bonds provided the main product ions and the most abundant and selective ones are proposed for quantitation and confirmation purposes in MRM mode. The LC-MS/MS method developed has been applied to the analysis of vegetables. A simple clean-up procedure using hydrophilic–lipophilic-balanced cartridges was applied to several vegetable extracts from tomato, zucchini, chard and lettuce, obtaining recoveries >80% for both compounds. The high matrix suppression observed for KAS in all matrices was reduced by a 1 : 5 sample dilution with acetonitrile, providing a 100-fold improvement in sensitivity for this compound. Method quality parameters have been established for tomato matrices, obtaining method limits of quantitation in the low µg kg−1 level (5–10 µg kg−1) for both compounds, precisions expressed in %RSD better than 7% and accuracies expressed as relative error better than 8% at the 100 µg kg−1 level, making this method suitable for routine analysis.

A novel LC-MS/MS method has been developed for the determination of 13 aminoglycoside antibiotics in meat products. Among the chromatographic columns tested, the mixed-mode Obelisc R provided the best performance. Electrospray has been used for the coupling of the LC and the effect of temperature on the ionization has been evaluated. The mass spectra of AGs have been studied in order to select the most adequate precursor and product ions for quantitation and confirmation in SRM mode, showing that the single charged [M+H](+) provided better precisions than the double charged [M+2H](2+). Accurate mass measurements have been performed in order to confirm the molecular composition of the product ions, allowing the establishment of a new mechanism for some product ions of STR and DHSTR. A sample treatment based on an extraction and a SPE clean-up has been applied to a wide variety of meat products such as frankfurters; sausages; and minced meat of pork, veal, and chicken. Method limits of quantitation in the low microgram per kilogram level (1-50 μg kg(-1)), precisions %RSD below 15 % and accuracies expressed as relative errors below 23 % have been obtained, making the proposed method suitable for routine analysis.

In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg.

A total of seventy samples of drinking water were tested for non-controlled and illicit drugs. Of these, 43 were from Spanish cities, 15 from seven other European countries, three from Japan and nine from seven different Latin American countries. The most frequently detected compounds were caffeine, nicotine, cotinine, cocaine and its metabolite benzoylecgonine, methadone and its metabolite EDDP. The mean concentrations of non-controlled drugs were: for caffeine 50 and 19 ng L(-1), in Spanish and worldwide drinking water respectively and for nicotine 13 and 19 ng L(-1). Illicit drugs were sparsely present and usually at ultratrace level (

Pentachlorophenol (PCP) is globally dispersed and contamination of soil with this biocide adversely affects its functional biodiversity, particularly of fungi - key colonizers. Their functional role as a community is poorly understood, although a few pathways have been already elucidated in pure cultures. This constitutes here our main challenge - elucidate how fungi influence the pollutant mitigation processes in forest soils. Circumstantial evidence exists that cork oak forests in N. W. Tunisia - economically critical managed forests are likely to be contaminated with PCP, but the scientific evidence has previously been lacking. Our data illustrate significant forest contamination through the detection of undefined active sources of PCP. By solving the taxonomic diversity and the PCP-derived metabolomes of both the cultivable fungi and the fungal community, we demonstrate here that most strains (predominantly penicillia) participate in the pollutant biotic degradation. They form an array of degradation intermediates and by-products, including several hydroquinone, resorcinol and catechol derivatives, either chlorinated or not. The degradation pathway of the fungal community includes uncharacterized derivatives, e.g. tetrachloroguaiacol isomers. Our study highlights fungi key role in the mineralization and short lifetime of PCP in forest soils and provide novel tools to monitor its degradation in other fungi dominated food webs.

“On-Line” preconcentration in capillary electrophoresis (CE) is a good strategy to overcome the low concentration sensitivity of the technique, which is the main limitation when trace-level compounds are to be determined in complex matrices such as biological samples. Here we discuss the use of at-, on-, and in-line preconcentration procedures in combination with CE in the analysis of biological fluids. The preconcentration strategies discussed are classified into two groups depending on the mechanism involved: chromatographic or electrophoretic techniques. Recent applications are included and the advantages and drawbacks of the techniques are examined.

Sedimentation field flow fractionation separation associated with flow cytometry has been used for the characterization of several commercial Saccharomyces cerevisiae yeasts used for wine production. A new type of channel 80 microm thick and new operating conditions, such as sample introduction when field and flow are established and a channel inlet connected to the accumulation wall, were used. Good repeatability (5% RSD) and reduced analysis time (2-10 min) were obtained. The avoidance of the stop-flow relaxation process in conjunction with the use of a channel of reduced thickness has demonstrated that an effective "steric-hyperlayer" mode driving to a major focusing effect of the species in the channel thickness is involved in the elution of the yeast cells. Flow cytometry analyses were performed, and the forward scattering and side scattering yeast characteristics correlation maps were obtained. Field flow fractionation and flow cytometry information obtained indicated that the fractogram profiles of the yeast cell depended not only on the size, but also on the shape and density.

Various types of glycosaminoglycans (GAGs) including heparins, chondroitin sulfates, dermatan sulfate and hyaluronic acid were studied from their proton nuclear magnetic resonance (1H NMR) spectra using chemometric techniques. Despite the complexity of the 1H NMR signals, data analysis using principal component analysis enabled the different GAG classes to be distinguished and permitted their classification according to their chemical structure. The analysis of the composition of the major disaccharide unit and other relevant chemical structures in the heparin samples was performed using partial least squares regression.

Fifty samples of finished drinking waters (FDWs) from Spain covering 12 million inhabitants were tested for 53 pharmaceuticals pertaining to 12 different Anatomical Therapeutic Chemical (ATC) classification system codes. The studied compounds are a combination of most commonly consumed pharmaceuticals with other barely reported in the literature. Five compounds, azithromycin, clarithromycin, erythromycin, sulfamethoxazole, and ibuprofen were tentatively identified by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in some samples (2 to 15 %), but only ibuprofen and azithromycin could be confirmed when analyzed by liquid chromatography–high-resolution mass spectrometry (LC-HRMS) with a quadrupole-Orbitrap instrument. Concentration levels of ibuprofen in the positive samples ranged from 12 to 17 ng/L (n = 6) while for azithromycin values from 5 to 9.5 ng/L (n = 3) were found. Ibuprofen fragmentation behaviour in different mass spectrometry instrument configurations (triple quadrupole, quadrupole-ion trap, and quadrupole-Orbitrap) was evaluated.

This paper shows the use of three-way data analysis methods to improve resolution and quantification in poorly separated peaks from capillary zone electrophoresis (CZE). Second-order data (data matrices) obtained with a diode array detector (DAD) are analyzed. There is a large overlap in the electrophoretic time domain and the data do not have a strict trilinear structure. These shortcomings might hinder the mathematical resolution. However, three-way methods allow the pure electrophoretic profiles of the analytes to be recovered in an unknown mixture, even in the presence of uncalibrated interferences. Furthermore, the analyte can be quantified in unknown mixtures with reasonable accuracy using pure standards. As an example, ebrotidine metabolites were chosen to test the method.

Capillary zone electrophoresis with diode-array detection was applied to the separation of ebrotidine and its metabolites. However, three of these, which are neutral in the conditions studied, co-migrated with the electroosmotic flow signal. Therefore, strongly overlapping peaks were observed. The main aim of this study was to show the potentiality of capillary electrophoresis in combination with chemometrics. Multivariate calibration methods were applied to quantify these analytes in synthetic mixtures. The results obtained using partial least squares (PLS) were in agreement with actual values, with an overall prediction error of 9.7%.

This paper illustrates the possibilities of chemometric methods in the resolution and quantification of various compounds in overlapping peaks from capillary electrophoresis. Ebrotidine and most of its metabolites were efficiently separated by capillary zone electrophoresis (CZE) in a fused-silica capillary. However, the procedure was not suitable for the physical separation of the three less ionizable metabolites, which comigrated and overlapped with the electroosmotic flow signal. Multivariate curve resolution based on an alternating least squares procedure was used for their mathematical resolution. For such a purpose, data obtained in the CZE system with a diode array detector, which consisted of UV spectra registered over time, were analyzed. The ebrotidine metabolites were successfully resolved and quantified in synthetic mixtures and urine samples.

A 1H NMR method for the quantification of dermatan sulfate impurities in heparin industrial samples is proposed. The method is based on the analysis of 1H NMR spectral data by multivariate calibration. The 1H NMR spectra of heparin and dermatan sulfate standards showed characteristic profiles. Thus, differences in the methyl peaks of acetamido groups of heparin and dermatan sulfate were greatly advantageous for the analysis. Other hydrogens of the sugar ring were also relevant in this study. Thus, the determination of dermatan sulfate by multivariate calibration depended on all these differences. Partial least squares regression (PLS) was chosen as the calibration method. In addition, a data standardization procedure was developed in order that 1H NMR spectra registered with different instruments operating under different measurement conditions were comparable. The quantification of dermatan sulfate in the samples was satisfactory, with an overall prediction error of 6%.

In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg.

Veterinary medicines are widely administered to farm animals since they keep animals healthy at overcrowded conditions. Nevertheless the continuous administration of medicines to farm animals can frequently lead to the presence of residues of veterinary drugs in consumption products. Amprolium is a quaternary ammonium compound used in the treatment of coccidiosis. In this paper a method based on capillary zone electrophoresis (CZE) to analyze residues of amprolium in eggs was developed and validated for the first time. Parameters such as electrolyte type, concentration and pH were optimized. In order to improve sensitivity, field amplified sample injection (FASI) was used for in-line preconcentration after a quick and simple sample treatment based on SPE (Envi-Carb). During method validation studies using egg samples a matrix interference was found at the migration time of amprolium. This compound was identified as thiamine and confirmed by MSn experiments using capillary electrophoresis coupled to mass spectrometry (CE-MS) with an ion-trap mass analyzer. CZE conditions were re-optimized to separate thiamine from amprolium allowing the quantification of amprolium in eggs at concentrations down to 75 µg Kg-1, which are far below the MRL legislated values.

The efficiency and the reproducibility of different solid-phase adsorbents such as C18 cartridges, C18 and poly(styrene-divinylbenzene) (PS-DVB) membrane extraction disks were evaluated for the extraction of phenols from water at μg 1−1 concentration levels. Liquid chromatography with electrochemical detection (LC-ED) was used for the analysis of the organic extracts. A phosphate buffer-acetonitrile-methanol mixture as mobile phase and coulometric detection at + 750 mV were used. High recoveries (70–98%) and good reproducibility (relative standard deviation between 3 and 12%) were obtained using PS-DVB disks, which can be recommended for the enrichment of samples with low concentration of phenols (0.5 μg 1−1). For more concentrated samples (10 μg 1−1), the use of C18 cartridges was preferred because smaller solvent and sample volumes were used and the analysis time was reduced.

As the interest in the use of fullerene compounds in biomedical and cosmetic applications increases, so too does the need to develop methods for their determination and quantitation in such complex matrices. In this work, we studied the behavior of C60 and C70 fullerenes in non-aqueous capillary electrophoresis, as well as two C60 fullerene derivatives not previously reported by any electrophoretic method, N-methyl-fulleropyrrolidine and (1,2-methanofullerene C60)-61-carboxylic acid. The separation was performed using fused-silica capillaries with an I.D. of 50 μm and tetraalkylammonium salts, namely tetra-n-decylammonium bromide (200 mM) and tetraethylammonium bromide (40 mM), in a solvent mixture containing 6 % methanol and 10 % acetic acid in acetonitrile/chlorobenzene (1:1 v/v) as the background electrolyte. Detection limits, based on a signal-to-noise ratio of 3:1, were calculated, and values between 1 and 3.7 mg/L were obtained. Good run-to-run and day-to-day precisions on concentration were achieved with relative standard deviation lower than 15 %. For the first time, an electrophoretic technique has been applied for the analysis of C60 fullerene in a commercial cosmetic cream. A standard addition method was used for quantitation, and the result was compared with that obtained by analyzing the same cream by liquid chromatography coupled to mass spectrometry.

Micellar electrokinetic chromatography (MEKC) has been applied for the determination of 5-hydroxymethylfurfural in several foodstuffs. A 75 mM phosphate buffer solution at pH 8.0 containing 100 mM sodium dodecylsulphate was used as background electrolyte (BGE), and the separation was performed by applying +25 kV in a 50 μm I.D. uncoated fused-silica capillary. Good linearity over the range 2.5–250 mg kg −1 ( r 2 ⩾ 0.999) and run-to-run and day-to-day precisions at low and medium concentration levels were obtained. Sample limit of detection (0.7 mg kg −1 ) and limit of quantification (2.5 mg kg −1 ) were established by preparing the standards in blank matrix. The procedure was validated by comparing the results with those obtained with liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Levels of HMF in 45 different foodstuffs such as breakfast cereals, toasts, honey, orange juice, apple juice, jam, coffee, chocolate and biscuits were determined.

9 pages, 4 tables, 3 figures.-- PMID: 18052095 [PubMed].-- Printed version published on Dec 26, 2007., This paper reports on the applicability of gas chromatography coupled to ion-trap tandem mass spectrometry (GC/ITMS/MS) for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in food. MS/MS parameters were selected to achieve the high sensitivity and selectivity required for food analysis. Good precision (RSD = 5–18% for PCDD/Fs and 6–14% for dl-PCBs) and low limits of detection for PCDD/Fs (0.1–0.93 pg/g of fat) and dl-PCBs (0.1–0.89 pg/g of fat) were obtained. A comparative study of the congener-specific determination using both GC/ITMS/MS and GC-high resolution mass spectrometry (GC/HRMS) was performed by analyzing several matrices such as milk, fish oil, chicken, pork, fish, eggs, and a chicken compound feed, at low pg/g levels. The results using GC/ITMS/MS were in good agreement with those obtained by GC/HRMS. Consequently, GC/ITMS/MS is proposed for the analysis of PCDD/Fs and dl-PCBs in food and feed samples., We gratefully thank the Ministerio de Ciencia y Tecnología under Project CTM2006-00753/TECNO and EU Project DIFFERENCE (G6RD-CT-2001-00623) for financially supporting this study.

A new, simple and selective method for the analysis of 5-hydroxymethylfurfural (HMF) in foods by liquid chromatography coupled to ion trap multi-stage mass spectrometry (LC-MS(n)) is proposed in the present study. Several chromatographic columns were tested and the best results were obtained using a phenyl fluorinated column. MS conditions were established using an atmospheric pressure chemical ionisation (APCI) source in the positive ionisation mode. MS/MS was used for quantitative analysis while MS(3) was required for confirmation purposes. Quality parameters such as day-to-day and run-to-run precision (RSD

The high separation efficiency and loading capacity of capillary electrochromatography (CEC) make it an attractive separation mode for coupling with mass spectrometry (MS), which has the ability to unambiguously identify analytes with high selectivity and sensitivity. We present an overview of recent advances on both instrumentation and separation columns employed in CEC-MS systems. In particular, the main characteristics of the stationary phases, as well as the configurations of the column outlet that are related with the coupling arrangements of the MS ionization sources, are reported. At present, packed columns and conventional electrospray ionization (ESI) sources are mainly employed in CEC-MS. Nevertheless, the use of monolithic capillary columns and nanoelectrospray sources has the potential for wide acceptance in the next future. Moreover, the main features of several mass analyzers including ion trap, quadrupole, time-of-flight, magnetic sector, and Fourier transform-ion cyclotron resonance are examined. Finally, current applications of this technology, mainly in the pharmaceutical field and proteomics, are reviewed.

This paper shows the potentiality of capillary electrophoresis (CE) coupled to mass spectrometry (MS) for the analysis of heterocyclic aromatic amines obtaining good results in terms of sensitivity and precision. These compounds have a special interest since they can be carcinogenic for humans. The optimization of a CE-MS method was performed and the best conditions were obtained using a 16 mM formic acid/ammonium formate solution at pH 4.5 with 60% methanol as running electrolyte. For CE-MS coupling, a sheath liquid methanol/20 mM formic acid (75/25) solution at a flow rate of 3 microL/min and hydrodynamic injection of methanol mixtures for 10 s were used. Detection limits ranging from 18 ng/g to 360 ng/g and precisions up to 1.4% and 12% for migration time and concentration, respectively, were obtained. In order to improve sensitivity, field-amplified sample injection was applied as an in-line preconcentration method. Methanol/5 mM formic acid (50/50) as a sample solvent, 3 s hydrodynamic injection (0.5 psi) of a methanol plug, and 25 s of electrokinetic injection (10 kV) of the sample were found to be the optimum conditions. Detection limits up to 25 times lower and similar precisions than those reported for hydrodynamic injection were obtained.

□ Ebrotidine is a new H 2 -receptor antagonist which exhibits a remarkable ability for gastric mucosal protection. A preliminary metabolic pathway for this compound was proposed and the hypothetic metabolites were synthesized. The presence of ebrotidine and its metabolites ebrotidine S -oxide and 4-bromobenzenesulfonamide in human urine has been confirmed by HPLC separation and spectroscopic characterization of the collected fractions by FT-IR and 1 H NMR. Ebrotidine S , S -dioxide has been identified by HPLC using diode-array detection.

Analytical procedures for the determination of free and total sulfate and phosphate in glycosaminoglycans by high-performance liquid chromatography were studied. A column-switching method coupling high-performance size-exclusion chromatography (HPSEC) and ion chromatography (IC) is proposed for the determination of free anions. Good run-to-run and day-to-day precision values (RSD) of < 4.7% were obtained for both anions. Total anion contents were determined after wet acid hydrolysis with nitric acid-hydrogen peroxide (5 + 1) by single-column IC and ICP-AES elemental analysis in order to validate the results. Recoveries ranging from 94.6 to 99.0% for sulfate and from 80.8 to 94.0% for phosphate were obtained. Both HPSEC-IC and single-column IC methods were applied to the analysis of a low molecular mass heparin, a non-fractionated heparin and a chondroitin 4-sulfate. From the free and total sulfate determinations, the content of linked sulfur was calculated and ranged from 5.1 to 12.2% m/m.

Publisher Summary Phenolic compounds are ubiquitous in the environment. They occur as natural constituents and mediate in many industrial processes—for example, in the manufacture of plastics, dyes, drugs, and antioxidants. Phenols are also breakdown products from natural organic compounds, such as humic substances, lignins and tannins, which are widespread in the environment. The environmental half-lives of most chlorophenols are short, rarely as long as a month: once discharge ceases, levels drop rapidly due to bacterial breakdown. Apart from water problems, chlorophenols can be adsorbed into the soil. The adsorption and desorption of chlorophenols from soils depend on the number of chlorine substituents and also on their position on the phenolic ring. Pentachlorophenol (PCP) can be assimilated by humans through inhalation, skin penetration, and the digestive system, and may cause toxic damage to the liver and changes in the immunological system. Gas chromatography (GC) is extensively used for the analysis of phenolic compounds in water, sludges, and soil samples due to some advantages such as high separation efficiency, resolution, and sensitivity, as well as its rapidity of analysis.

Optimum conditions for the separation of positional isomers of chlorophenols by capillary zone electrophoresis (CZE) were established. The behavior of five volatile electrolytes (L-cysteic acid, 3-amino-1-propanesulfonic acid, aminomethanesulfonic acid, diethylmalonic acid, and ammonium acetate) was compared. The best performance based on low electrophoretic current and high separation efficiency was obtained for diethylmalonic acid as working electrolyte. The influence of pH on the separation, using both uncoated fused-silica capillaries and modified capillaries (NaAMPS from EKT) with anionic coating, was discussed. Moreover, the effect of electrolyte concentration and applied voltage using fused-silica capillaries was studied. The optimum CZE conditions that allowed the separation of 16 chlorophenols were 20 kV, 30 mM diethylmaIonic acid, pH 7.25, and uncoated fused-silica capillary. Figures of merit such as run-to-run and day-to-day precision, linearity, and limits of detection were calculated.

A method based on ultra-high performance liquid chromatography (UHPLC) is proposed for the determination of chloramphenicol (CAP), its related compounds, thiamphenicol (TAP) and florfenicol (FF), and the polar metabolite florfenicol-amine (FFA), in animal-derived foods (chicken and pork meat, fish, prawns and honey). For the retention of FFA and its simultaneous analysis with the parent compounds a phenyl-hexyl column is proposed. A fast separation is achieved in less than 2 minutes using a methanol : acetic acid-ammonium acetate buffer (5 mM, pH 5) and gradient elution. Under these conditions, the FFA is retained at more than twice the dead volume, as recommended by the legislation. For the coupling with mass spectrometry, heated-electrospray (H-ESI) is used as ionisation source improving vaporization efficiency. To prevent interferences using selected-reaction monitoring (SRM) both quantitation and confirmation transitions were carefully selected. Two different sample treatments based on solid-phase extraction with mixed-mode cartridges for fish and meat products and hydrophilic-lipophilic-balanced cartridges for honey are proposed, providing limits of quantitation (LOQs) below μg kg(-1) level.