Polymeric Solid-phase Extraction Cartridges Research Articles

Determination of Aminophosphonate Herbicides in Glutamate Loaded Spice Mix by LC-IDMS and Method Extension to Other Food Matrices

The accumulation of organophosphorus type herbicides has been observed worldwide in the environment (i.e. soil, water), together with their appearance in foods of plant origin. This paper reports a new liquid chromatography–isotope dilution–tandem mass spectrometric method (LC-IDMS) for the analysis of glufosinate (GLUF), glyphosate (GLY) and its main metabolite, aminomethylphosphonic acid (AMPA), in challenging food samples. Sample preparation is based on aqueous extraction with ethylenediaminetetraacetic acid solution, followed by solid-phase extraction (SPE) on mixed-mode cation exchange cartridges to remove matrix constituents before derivatization with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl). Derivatized samples were cleaned up on hydrophilic modified polymeric SPE cartridge. This two-step SPE supported sample preparation approach, and the LC-IDMS separation carried out in negative ionization mode resulted in fit-for-purpose recovery (81–118%) and precision (4–18%) in the validation of glutamate loaded spice mix, mushroom, maize and cherry samples. Amino acid content influencing FMOC derivatization efficiency was estimated with a HILIC-MS/MS setup. Multiple reaction monitoring (MRM) was assisted with high-resolution (QTOF) accurate mass data on the FMOC-derivatized GLUF, GLY and AMPA standards. The limit of quantification (LOQ) was 0.005 mg/kg for all the three analytes. The method was successfully applied on quality control samples (oat and arugula) with fit-for-purpose accuracy (99–120%) and on other nineteen real samples, where GLY and AMPA were detected in the range between 0.005 and 0.069 mg/kg.

Rapid and reliable detection of glyphosate in pome fruits, berries, pulses and cereals by flow injection – Mass spectrometry

A flow injection – mass spectrometry method for rapid glyphosate detection in food commodities was developed and validated. The sample preparation protocol included a simple and rapid extract purification step through polymeric solid phase extraction cartridges followed by addition of isotopically labeled glyphosate to the final test sample. The optimized method was subjected to intra-laboratory validation (spiking range 0.5–100 mg/kg) in chickpeas, grapes and apples, as representatives of three different commodity groups as defined in SANTE/11813/2017 guidelines. Recoveries were in the range 60–111%, repeatability and within laboratory reproducibility were ≤17%.The trueness of the results generated with the developed method was evaluated by analysis of a set of incurred chickpea and wheat samples (glyphosate range 0.5–36 mg/kg) and comparison with the reference method (Quick Polar Pesticides Method), confirming the method fitness-for-purpose of rapid compliance testing.

Determination of Antimicrobial Residues in Honey by Liquid Chromatography Tandem Mass Spectrometry

Antibiotics are generally used worldwide against bacterial diseases in the treatment of food-producing animals. Since the residues of active agents or their metabolites can appear in these foods, the European Union, for instance, has set maximum residue limit concentrations for authorised veterinary drugs in foodstuffs. However, as yet, regulatory limits have not been established for honey and thus far, only recommendations exist. The aim of this study is to present a multiscreening method for residues in honey for the determination of 36 antimicrobial residues associated with several antibiotics of the B1 group (sulfonamides, trimethoprim, aminoglycosides, tetracyclines, quinolones and lincomycin) as well as the antibiotic griseofulvin. During the screening analysis, samples are hydrolysed in an acidified medium, purified on polymeric solid-phase extraction cartridges and subsequently analysed by reversed phase ion pair liquid chromatography tandem mass spectrometry. The liquid chromatographic separation was optimised by computer simulation with DryLab software. The positive identification of target compounds in suspicious samples was confirmed using earlier developed antibiotic class specific methods of which the aminoglycoside method is herein described in detail. The developed approaches were then applied to samples in the national monitoring program after their successful validation. Moreover, the screening and confirmatory methods were applied to proficiency test samples resulting in satisfactory identification and quantification. However, the analysis of real samples revealed that co-eluting target compounds can have considerable influence on the accuracy of this semi-quantitative multiscreening method.

Determination of T-2 and HT-2 Toxins in Oats and Oat-Based Breakfast Cereals by Liquid-Chromatography Tandem Mass Spectrometry.

This protocol specifies an accurate and sensitive method for the determination of T-2 and HT-2 toxins content in oats and oat-based foods using liquid chromatography with tandem mass spectrometry detection. T-2 and HT-2 toxins are extracted from the test material with a mixture of acetonitrile and water. The filtered extract is dried, reconstituted with a mixture of methanol and water, then purified on a polymeric solid-phase extraction cartridge. Toxins are finally eluted from the column with methanol and quantified by reversed phase high performance liquid chromatography with tandem mass spectrometry detection.

Screening of multiple drugs of abuse and metabolites in urine using LC/MS/MS with polarity switching electrospray ionization

A recent trend in urine drug testing in forensic and clinical toxicology has been the simultaneous determination of different chemical groups of target drugs, which are selected based on their local popularity. Rapid multiple drug analysis, made possible by the use of liquid chromatography-tandem mass spectrometry (LC/MS/MS), has become more widely used, especially in workplace drug testing. Therefore, in the present study, a method for simultaneously analyzing 35 drugs of abuse and relevant metabolites that are most prevalent in Korea, using LC/MS/MS with polarity switching electrospray ionization, was developed and validated. The drugs and metabolites in urine were extracted by using mixed mode strong cation exchange polymeric solid phase extraction cartridges after enzymatic hydrolysis and were then injected into the LC/MS/MS system. The validation results for selectivity, linearity, intra- and inter-assay precision and accuracy for this method were satisfactory, while the results for matrix effects and recovery showed significant variance among the urine samples from different sources. The limits of detection ranged from 0.1 to 10 ng/ml and the limits of quantification were from 1 to 10 ng/ml. To reduce the matrix effects in authentic samples, two different quantitative approaches were compared: quantification using calibration standards prepared by the drug-free pooled urine matrix and quantification using the standard addition. Of these, the latter method was found to be the most suitable. The method developed in this study will be very useful for forensic and clinical toxicology laboratories to adopt for monitoring the inappropriate use of controlled drugs.

Quantitative analysis of mycotoxins in cereal foods by collision cell fragmentation-high-resolution mass spectrometry: performance and comparison with triple-stage quadrupole detection

A liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method for the simultaneous determination of aflatoxins (B1, B2, G1, G2), ochratoxin A, deoxynivalenol, zearalenone, T-2 and HT-2 toxins in wheat flour, barley flour and crisp bread was developed. Mycotoxin fragmentation patterns obtained by high-energy collision dissociation (HCD) were investigated to obtain quantitative and confirmatory information (two characteristic masses per mycotoxin) using Orbitrap™-based high-resolution mass spectrometry. LC-HRMS (full-scan) detection carried out by HCD allows the monitoring of the pseudo-molecular ion and an additional characteristic fragment (for each mycotoxin) with mass accuracy in the range 0.1–3.9 ppm, meeting current European regulatory requirements for LC-MS confirmatory analysis. A sample preparation procedure based on polymeric solid-phase extraction cartridges was applied, allowing recoveries higher than 74% for nine mycotoxins, with a relative standard deviation lower than 13%. Detection limits in the range 0.5–3.4 µg kg−1 were obtained for three cereal matrices. A critical comparison between the proposed method and a validated method based on triple quadrupole mass spectrometry showed similar performance in terms of detection limits, recoveries and repeatability, and matrix effects. Based on an efficient sample extraction and clean-up, the LC-HCD-HRMS method reported here represents a reliable and robust alternative tool for mycotoxin analysis in food matrices as compared with well-established triple quadrupole-based approaches.

Determination of Antibiotics in Brazilian Surface Waters Using Liquid Chromatography–Electrospray Tandem Mass Spectrometry

A liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) method for the determination of antibiotics in water was developed and applied to Brazilian surface waters. Amoxicillin, ampicillin, cefalexin (CEF), ciprofloxacin (CIP), norfloxacin (NOR), sulfamethoxazole, tetracycline (TET), and trimethoprim were selected as target compounds due to their high consumption pattern in Brazil. LC and MS conditions were optimized to produce the maximum analytic response for each compound. Anion exchange and polymeric solid-phase extraction cartridges, in series, were employed during the extraction procedures. Recovery, linear range, limit of detection (LOD), and limit of quantification were calculated. LOD varied from 0.13 ng L(-1) for CIP and NOR to 0.76 ng L(-1) for TET. Surface water samples from the Atibaia watershed (São Paulo State, Brazil) were analyzed. Results showed that seasonal and anthropogenic aspects dictated the levels of antibiotics in the samples. An overall frequency of detection of 55% was observed during the rainy period, whereas a higher percentage (88%) was noticed for samples collected during the dry season. In the Atibaia River, sample concentrations ranged from 29 ng L(-1) for CEF to 0.5 ng L(-1) for NOR. In a sewage-affected stream, however, concentrations up to 2422 ng L(-1) CEF were found.

Determination of quinolone residues in tilapias (Orechromis niloticus) by HPLC-FLD and LC-MS/MS QToF

A method for the simultaneous determination of flumequine, oxolinic acid, sarafloxacin, danofloxacin, enrofloxacin, and ciprofloxacin in tilapia (Orechromis niloticus) fillet, using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) is presented. The quinolones were extracted from the food matrix with a solution of 10% trichloroacetic acid and methanol (80:20 v/v). Clean-up of the extract was performed using polymeric solid-phase extraction cartridges. Identification of the quinolones was confirmed by liquid chromatography-tandem mass spectrometry. The HPLC-FLD method was validated in-house and the following analytical parameters were obtained: linearity higher than 0.99 for all the quinolones; intra- and inter-assay precisions were lower than 3.5% and 10.9%, respectively; and recoveries ranged from 73% to 110%. The limit of quantification was below the maximum residue limit established by the Joint Expert Committee on Food Additives (JECFA), which indicates that the method is appropriate for the determination of quinolones in fish fillet.

Simultaneous determination of phenolic acids and flavonoids in Lycium barbarum Linnaeus by HPLC–DAD–ESI-MS

A high-performance liquid chromatography–diode array detection–mass spectrometry method with electrospray ionization mode (HPLC–DAD–ESI-MS) was developed for simultaneous determination of phenolic acids and flavonoids in fruits of Lycium barbarum Linnaeus, a widely used traditional Chinese herb possessing vital biological activity. Both phenolic acids and flavonoids were extracted with 50% ethanol and purified using a polymeric solid phase extraction cartridge followed by HPLC–DAD–ESI-MS analysis. By employing a Vydac C18 column, a total of 52 phenolic acids and flavonoids were separated within 70 min using a gradient mobile phase of 0.5% (v/v) formic acid in water and acetonitrile–water (94:6, v/v) with flow rate at 1 mL/min, column temperature at 30 °C and detection wavelength at 280 nm. Of 52 compounds, 15 phenolic acids and flavonoids were positively identified based on both absorption and mass spectra, with the remaining 37 tentatively identified by comparison of absorption spectra with reported values in the literature. Internal standards 3-hydroxybenzoic acid and hesperidin were used for quantitation of phenolic acids and flavonoids, respectively. Among the 15 positively identified compounds, quercetin-rhamno-di-hexoside was present in largest mass fraction (438.6 μg/g), followed by quercetin-3-O-rutinoside (281.3 μg/g), dicaffeoylquinic acid isomers (250.1 μg/g), chlorogenic acid (237.0 μg/g), quercetin-di-(rhamnohexoside) (117.5 μg/g), quercetin-di-(rhamno)-hexoside (116.8 μg/g), kaempferol-3-O-rutinoside (97.7 μg/g), isorhamnetin-3-O-rutinoside (72.1 μg/g), p-coumaric acid (64.0 μg/g), caffeic acid (23.7 μg/g) and vanillic acid (22.8 μg/g).

Quantitation and identity confirmation of residues of quinolones in tilapia fillets by LC-ESI-MS-MS QToF

A method for simultaneous determination of flumequine (FLM), oxolinic acid (OXO), sarafloxacin (SAR), danofloxacin (DAN), enrofloxacin (ENR), and ciprofloxacin (CIP) in tilapia (Orechromis niloticus) fillets, using liquid chromatography-tandem mass spectrometry (LC-ESI-MS-MS QToF) is presented. The quinolones were extracted from the food matrix with a solution of 10% trichloroacetic acid-methanol (80:20 v/v) with ultrasonic assistance. Clean-up of the extract solution was performed by using polymeric solid-phase extraction cartridges. The LC separation was carried out on an octadecyl hybrid silica column (C18, 150 mm x 3 mm, 5 microm). The column temperature was set at 30 degrees C, and gradient elution (0.2 mL min(-1)) was performed using water and acetonitrile, both containing 0.1% of acetic acid, as mobile phase components. The analytes were ionized using electrospray in the positive polarity mode. The following analytical results were obtained: linearity was about 0.99 for all the quinolones; intra and inter-assay precision (RSD%) were lower than 12.7 and 20%, respectively; and recoveries were from 89 to 112%. The quantitation limits were below the maximum residue limits established for the analytes. The method is suitable for the determination of quinolone residues in fish fillets and the QToF technique made it possible to obtain m/z ratios with less than 10 ppm of error for each analyte.

Liquid chromatography/tandem mass spectrometry determination of organophosphorus flame retardants and plasticizers in drinking and surface waters

A liquid chromatography/electrospray ionization tandem mass spectrometric method for analyzing organophophorus flame retardants and plasticizers in drinking and environmental waters was developed. Five alkyl phosphates, three chlorinated alkyl phosphates, two aryl phosphate and triphenylphosphine oxide were selected for this study. These compounds were extracted from water samples by a hydrophilic polymeric solid-phase extraction cartridge. Accuracy and precision were evaluated analyzing 0.5 L of water samples spiked at concentrations of 10 and 100 ng/L for drinking water and at 300 and 1000 ng/L for river water. Except for trimethyl phosphate, analyte recoveries were better than 80%, and were not dependent on the type of aqueous matrix in which they were dissolved. At the spike levels considered, within-day precision was between 3 and 12% for tap water and between 4 and 14% for river water, and estimated method quantification limits ranged from 0.2 to 3.9 ng/L. A short survey conducted by analyzing some river water samples (River Tiber) ascertained the presence of ten organophosphorus compounds at concentration levels ranging from a few nanograms per liter to 323 ng/L for tris(2-butoxyethyl) phosphate.

Confirmation of Sulfamethazine, Sulfathiazole, and Sulfadimethoxine Residues in Condensed Milk and Soft-Cheese Products by Liquid Chromatography/Tandem Mass Spectrometry

A liquid chromatography/tandem mass spectrometry method (LC/MS/MS) is described for the simultaneous detection of 3 sulfonamide drug residues at 1.25 ppb in condensed milk and soft-cheese products. The 3 sulfonamide drugs of interest are sulfathiazole (STZ), sulfamethazine (SMZ), and sulfadimethoxine (SDM). The method includes extraction of the product with phosphate buffer, centrifugation of the diluted product, and application of a portion of the extract onto a polymeric solid-phase extraction cartridge. The cartridge is washed with water, and the sulfonamides are eluted with methanol. After evaporation, the residue is dissolved in 0.1% formic acid solution, and the solution is filtered before analysis by LC/MS/MS. The LC/MS/MS program involved a series of time-scheduled selected-reaction monitoring transitions. The transitions of MH+ to the common product ions at m/z 156, 108, and 92 were monitored for each residue. In addition, SMZ and SDM had a fourth significant and unique product ion transition that could be measured. Validation was performed with control and fortified-control condensed bovine milk with 2.5, 5, and 10 ppb sulfonamides. This method was applied to imported flavored and unflavored condensed milk and cream cheese bars. The presence of STZ and SMZ residues was confirmed in 3 out of 6 products.

Quantitative determination of four nitrofuran metabolites in meat by isotope dilution liquid chromatography–electrospray ionisation–tandem mass spectrometry

A confirmatory method based on isotope dilution liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been developed for the low-level determination of residues of four nitrofuran veterinary drugs in meat, e.g., furazolidone, furaltadone, nitrofurantoin, and nitrofurazone. The procedure entails an acid-catalysed release of protein-bound metabolites, followed by their in situ conversion into the 2-nitrobenzaldehyde (NBA) imine-type derivatives. Liquid–liquid extraction and clean-up on a polymeric solid phase extraction cartridge are then performed before LC–MS/MS analysis by positive electrospray ionisation (ESI) applying multiple reaction monitoring of three transition reactions for each compound. Reliable quantitation is obtained by using one deuterated analogue per analyte (d 4-NBA derivative) as internal standard (IS). Validation of the method in chicken meat was conducted following the European Union (EU) criteria for the analysis of veterinary drug residues in foods. The decision limits (CCα) were 0.11–0.21 μg/kg, and the detection capabilities (CCβ) 0.19–0.36 μg/kg, thus below the minimum required performance limit (MRPL) set at 1 μg/kg by the EU. The method is robust and suitable for routine quality control operations, and more than 200 sample injections were performed without excessive pollution of the mass spectrometer or loss of LC column performance.

Analysis of matrix-bound nitrofuran residues in worldwide-originated honeys by isotope dilution high-performance liquid chromatography-tandem mass spectrometry.

A sensitive and selective isotope dilution liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESIMS/MS) method is presented for the simultaneous analysis of the metabolites of four nitrofuran veterinary drugs, that is, furazolidone, furaltadone, nitrofurantoin, and nitrofurazone, in honey samples. The method entails a combined hydrolysis of protein-bound drug metabolites and derivatization of the resulting metabolites with 2-nitrobenzaldehyde (NBA) during an overnight incubation, followed by a liquid-liquid extraction and a cleanup on a polymeric solid-phase extraction cartridge. Mass spectral acquisition is carried out in the positive ion mode by applying multiple reaction monitoring (MRM) of three diagnostic transition reactions for each analyte under survey. A reliable quantification is obtained by the use of one deuterated analogue per analyte (NBA-d(4) derivative). The method has been validated in honey according to the European Union criteria for the analysis of veterinary drug residues in food. Expressed in underivatized nitrofuran metabolite concentrations, the decision limits (CCalpha) ranged within 0.07-0.46 microg/kg, and the detection capabilities (CCbeta) were within 0.12-0.56 microg/kg. The method has been successfully applied in a survey of honeys of various geographical origins, showing that furazolidone is the main nitrofuran antibiotic administered to treat bacterial diseases of bees.

Determination of Oxytetracycline Residues in Matrixes from a Freshwater Recirculating Aquaculture System

This paper describes related procedures to determine the amount of oxytetracycline (OTC) present in trout tissue (muscle with skin attached), biofilter sand, sediment, and tank water from a recirculating aquaculture system. OTC was extracted from the matrixes by different techniques, depending on complexity of the matrix and desired OTC detection level in that matrix. Listed in order of increasing complexity, OTC was extracted from tank water by dilution with acidic buffer containing ethylenediaminetetraacetic acid (EDTA); from biofilter sand by shaking with 0.1 N HCl; from sediment by homogenization and shaking with buffer/EDTA; and from ground trout by homogenization and shaking with buffer/EDTA (twice), with further cleanup and concentration of the extract on a polymeric solid-phase extraction cartridge. The 4 procedures all used the same reversed-phase gradient chromatography on a polymeric column with UV detection at 350 nm. The lower limit of detection (estimated) and upper limit of validation for each of these 4 matrixes were 0.04-4.0 microg/g (ppm; trout), 0.03-20 ppm (biofilter sand), 1-6000 ppm (sediment), and 0.003-10 ppm (water). Recoveries ranged from 82 to 108%, with relative standard deviation <20% over the applicable concentration ranges. These procedures were used to monitor OTC residues resulting from medicated feed administered to rainbow trout in a recirculating aquaculture system.

Quantification of BK1-5, the Stable Bradykinin Plasma Metabolite in Humans, by a Highly Accurate Liquid-Chromatographic Tandem Mass Spectrometric Assay

Bradykinin is a vasoactive nonapeptide involved in cardiorenal physiology and inflammatory states. It has been linked to the pathophysiology of hypertension and diabetes. Correlating levels of bradykinin with disease states has been hampered by its rapid degradation, artifactual production during blood sampling, and nonspecific radioimmunoassay techniques. We previously identified BK1-5 as the stable in vivo plasma metabolite of systemic bradykinin in humans. We now report a sensitive and specific assay method for BK1-5 in human blood utilizingliquid chromatography–tandem mass spectrometry(MS) with electrospray ionization. [13C2,15N]Glycine was incorporated into chemically synthesized BK1-5 for use as an internal standard. Blood samples (5 ml) were collected into 15-ml chilled ethanol to prevent artifactual kinin production and degradation. BK1-5 in ethanolic plasma supernatant was purified on a polymeric solid phase extraction cartridge. MS analysis was in the selective reaction monitoring mode. Precision of the assay is ±7.5% and accuracy is 99%. Recovery of BK1-5 through sample preparation was 43% and the lower limit of detection is 4 fmol/ml blood. Concentrations of BK1-5 in 12 normal volunteers were 44.2 ± 7.1 fmol/ml blood (mean ± SE). During blood sampling, no artifactual production of BK1-5 was detected for up to 60 s prior to denaturing the sample. This assay provides the first accurate and precise method using MS to quantify BK1-5 in human blood as a marker for the production of systemic bradykinin in humans.

Stability of sulfonated derivatives of benzene and naphthalene on disposable solid-phase extraction pre-columns and in an aqueous matrix

The stability of 14 sulfonated benzene and naphthalene compounds was investigated using polymeric solid-phase extraction cartridges, based on the styrene–divinylbenzene polymer Isolute ENV+. Several different storage conditions were tested to carry out the stability study in polymeric cartridges, which included storage at room temperature, at 4°C and at −20°C, during a period of up to 3 months. An additional stability study was carried out, not with the polymeric solid matrix, but in an aqueous matrix. This study was performed storing the samples at 4°C, during 2 months under three different conditions: acidifying the water sample to pH 2.5–3 with sulfuric acid, adding 1% of formaldehyde (additive used in waste water analyses), and storing the water sample at 4°C without any additives. The extraction of the SPE process is analyzed by ion-pair chromatography–electrospray mass spectrometry, in the negative ion mode. This study showed that the stability of polar aromatic sulfonic acids on disposable polymeric cartridges and in the water matrix is related to temperature and pH, respectively. Target aromatic sulfonated compounds stored in polymeric solid-phase extraction cartridges, are more stable at lower temperatures. The target analytes showed also good stability when stored in water at acidic pH. From the different analytes studied, substituted naphthalenesulfonates suffered more degradation than mononaphthalenesulfonates or benzenesulfonates under the experimental conditions of this work.

Tracing polar benzene- and naphthalenesulfonates in untreated industrial effluents and water treatment works by ion-pair chromatography-fluorescence and electrospray-mass spectrometry

This paper presents a protocol for the determination of a class of polar, ionic and highly water-soluble organic pollutants: benzene- and naphthalenesulfonic acids, compounds widely used in chemical, pharmaceutical, tannery, paper and textile industries. This protocol involves the use of a solid-phase extraction (SPE) followed by ion-pair chromatography-electrospray-mass spectrometry (IPC-ESI-MS). In this work two polymeric solid-phase extraction cartridges (Isolute ENV+ and Lichrolut EN) were compared, with the more effective being Isolute ENV+ sorbent. Recoveries and breakthrough volumes were calculated by loading volumes of 150, 200 and 300 ml of spiked ground water through the SPE columns. To enhance the effectiveness of the methodology, 1 ml of water containing 5 mM TEA was added before eluting with methanol. Average recoveries ranging from 70 to 100% were obtained for a variety of 13 analytes (only two naphthalenesulfonate compounds had recoveries below 50%.). Determination of benzene- and naphthalenesulfonates was accomplished by ion-pair chromatography-fluorescence detection (IPC-FLD). The ESI-MS parameters were optimized to achieve maximum sensitivity. [M–H] − ion was the base peak using low energies (fragmentor voltage: 80 V). Significant fragmentation of the quasi-molecular [M–H] − ion occurs at higher fragmentor voltages, leading to [M–SO 2H] −, [M–SO 3H] − and [SO 3] − as diagnostic ions, but with some sensitivity losses (more than two orders of magnitude when 150 V are applied as fragmentor voltage). Collision-induced dissociation (CID) of the parent ions for the benzene- and naphthalenesulfonates studied gave the [SO 3] − fragment ion common to sulfonated compounds, it has been shown to be characteristic of aromatic sulfonated compounds and could be used as a diagnostic tool to indicate the presence of these compounds. Limits of detection (signal-to-noise ratio = 3) ranging from 0.03 pg to 0.05 ng, were achieved when 150 ml of ground water were processed and quantified by IPC-FLD. In IPC-ESI-MS, time-scheduled SIM mode with post-column addition of 0.2 m min −1 of methanol was used. LODs range from 0.6 pg to 0.13 ng. In summary, with the development of a methodology based on SPE followed by IPC-ESI-MS, good sensitivity, structural information and unequivocal identification can be achieved. This protocol was applied to the analysis of surface waters, untreated industrial waste waters and wastewater treatment works effluents and influents. In the case of tannery effluent samples, isomers of naphthalenesulfonic acid were found as major pollutants in concentrations up to 0.8 and 1.0 mg l −1, for 1-naphthalenesulfonate and 2-naphthalenesulfonate, respectively. The main contaminants in wastewater treatment work samples were 2,6-naphthalenedisulfonate, 1-hydroxy-3,6-naphthalenedisulfonate, 3-nitrobenzenesulfonate, 1-naphthalenesulfonate and 2-naphthalenesulfonate, with levels of ug/l.

Determination of chlorobenzidines in industrial effluent by solid-phase extraction and liquid chromatography with electrochemical and mass spectrometric detection

The analysis of chloroanilines in industrial effluents is severely complicated by the total organic content (TOC) (10–100 mg/l) and high particle content, which reflects the presence of many compounds other than the analytes of interest. Therefore, both the extraction procedure and the application of a selective and sensitive detection technique are important. Five different polymeric solid-phase extraction cartridges were tested to extract chloroanilines and benzidines from Milli-Q and industrial effluent waters. The analyses were performed by liquid chromatography with electrochemical detection and with atmospheric pressure chemical ionization mass spectrometry in positive ionization mode. These techniques were used to detect several mono- and dichloroanilines in industrial effluents, which had a TOC between 1 and 70 mg/l.

Determination of sulfonated azo dyes in groundwater and industrial effluents by automated solid-phase extraction followed by capillary electrophoresis/mass spectrometry

One monosulfonated (Mordant Yellow 8) and seven disulfonated azo dyes (Acid Red 1, Mordant Red 9, Acid Red 13, Acid Red 14, Acid Red 73, Acid Yellow 23 and Acid Blue 113) were determined in spiked groundwater samples and industrial effluents by automated solid-phase extraction followed by capillary electrophoresis with UV detection and by capillary electrophoresis/mass spectrometry (CE/MS). The MS parameters were optimized to achieve maximum sensitivity and minimum fragmentation. The main ions observed were losses of Na+ cations replaced by hydrogen atoms. Two polymeric solid-phase extraction cartridges (Isolute ENV+ and LiChrolut EN) were compared for the preconcentration of 300 or 500 ml water samples. The recoveries varied from 64 to 80% for all dyes, with the exception of Acid Blue 113 and Acid Yellow 23, the recoveries of which varied from 15 to 34% when using Isolute ENV+. The protocol developed in this work was applied to the determination of sulfonated azo dyes in real samples from industrial effluents. The method detection limit ranged from 10 to 150 μg l-1 for CE/UV detection and from 100 to 800 μg l-1 for CE/MS under time-scheduled selected-ion monitoring conditions, with the exception of Acid Red 73 (>1700 μg l-1), which exhibited a low response. © John Wiley & Sons, Ltd.