Determination of pesticide residues and related compounds in water and industrial effluent by solid-phase extraction and gas chromatography coupled to triple quadrupole mass spectrometry

Pollution of drinking water supplies from industrial waste is a result of several industrial processes and disposal practices, and the establishment of analytical methods for monitoring organic compounds related to environmental and health problems is very important. In this work, a method using solid-phase extraction (SPE) and gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) was developed and validated for the simultaneous determination of pesticide residues and related compounds in drinking and surface water as well as in industrial effluent. Optimization of the method was achieved by using a central composite design approach on parameters such as the sample pH and SPE eluent composition. A single SPE consisting of the loading on a polymeric sorbent of 100 mL of sample adjusted to pH 3 and elution with methanol/methylene chloride (10:90, v/v) permitted the obtaining of acceptable recoveries in most cases. The concentration factor associated with sensitivity of the chromatographic analysis permitted the achievement of the method limit of detection values between 0.01 and 0.25 μg L^?1. Recovery assays presented mean recoveries between 70 and 120 % for most of the compounds with very good precision, despite the different chemical nature of the compounds analyzed. The selectivity of the method, evaluated through the relative intensity of quantification and qualification ions obtained by GC-QqQ-MS/MS, was considered adequate. The developed method was finally applied to the determination of target analytes in real samples. River water and treated industrial effluent samples presented residues of some compounds, but no detectable residues were found in the drinking water samples evaluated.     

Optimization of the Extraction and Analysis of Natural Androgen Steroids and Their Metabolites in Urine by GC/MS and GC/FID

A multiresidue method was developed for screening, quantification, and confirmation of nine natural androgen steroids and their metabolites in urine. Steroids were first extracted from urine by solid phase extraction, enzymatically deglucuronated, re-extracted using a liquid/liquid extraction for purification, and finally acetylated for GC/MS and GC/FID analysis. Each step of sample preparation, as well as analysis, was optimized: solid phase extraction, liquid/ liquid extraction, and derivatization reaction … Therefore, a rugged sample preparation procedure was developed leading to extracts of sufficient purity (recoveries >66% and few matrix compounds). The whole methodology allowed reliable detection and quantification of the nine steroids at low concentration levels. Linearity and repeatability were established and were found to be satisfactory (R² > 0.996, RSD < 11%). Finally, the method was applied to quantify compounds of interest in real samples collected from healthy volunteers and patients treated with 4-androstenedione or dehydroepiandrosterone.     

Development and Validation of a Dispersive Solid Phase Extraction Liquid Chromatography Mass Spectrometry Method with Electrospray Ionization for the Determination of Multiclass Pesticides and Metabolites in Meat and Milk

A dispersive solid phase extraction–liquid chromatography tandem mass spectrometry method with electrospray ionization was validated in food of animal origin for the determination of multiclass pesticide residues and their metabolites. A simple and low-cost sample preparation procedure using freezing as the clean-up step was used to identify and quantify analytes belonging to 39 different chemical classes in meat and milk matrices. Mean recoveries in the range of 70–120% with relative standard deviations <10% were obtained for the majority of the analytes. The limit of quantification of the method was 10 µg/kg. The matrix effects were statistically evaluated and the quantification of the analytes was conducted using calibration curves constructed with matrix matched calibration standards covering concentrations from 5 to 200 µg/kg. The proposed method was applied in 86 samples of animal origin taken from the Greek market, two of which were found positive for pesticides.     

Solid‐phase extraction coupled with ultra high performance liquid chromatography and electrospray tandem mass spectrometry for the highly sensitive determination of five iodinated X‐ray contrast media in environmental water samples

A highly sensitive method based on solid‐phase extraction and ultra high performance liquid chromatography with electrospray tandem mass spectrometry has been developed for simultaneous determination of five iodinated X‐ray contrast media in environmental water samples. Various solid‐phase extraction cartridges have been evaluated and a combination of LiChrolute EN and ENVI‐Carb solid phase extraction cartridges was selected for sample enrichment. The method was comprehensively validated on ground water, tap water, surface water, drinking water, and waste water by the conventional procedures: linearity, method detection limits, accuracy and precision, matrix effects. Good linearity (R² > 0.999), low detection limits (0.4–8.1 ng/L), satisfactory recoveries (55.1–109.5%) and precision (0.8–10.0% for intra‐day precisions and 0.6–16.5% for inter‐day precisions) were obtained for all the target compounds. Iopamidol, iohexol, and diatrizoate in some matrices were affected by matrix effects, which were slightly eased by using the isotope‐labeled internal standard. The developed method was successfully applied for real samples collected in Shanghai, China, with detected concentrations up to 2200 ± 200 and 9000 ± 1000 ng/L for iohexol and iopamidol, respectively.     

Online solid-phase extraction–liquid chromatography–electrospray–tandem mass spectrometry determination of multiple classes of antibiotics in environmental and treated waters

An online solid-phase extraction and liquid chromatography in combination with tandem mass spectrometry method was developed for the simultaneous determination of 31 antibiotics in drinking water, surface water and reclaimed waters. The developed methodology requires small sample volume (10 mL), very little sample preparation and total sample run time was 20 min. An Ion Max API heated electrospray ionization source operated in the positive mode with two selected reaction monitoring transitions was used per antibiotic for positive identity and quantification performed by the internal standard approach, to correct for matrix effects and any losses in the online extraction step. Method detection limits were in the range of 1.2–9.7, 2.2–15, 5.5–63 ng/L in drinking water, surface water and reclaimed waters, respectively. The method accuracy in matrix spiked samples ranged from 50–150 % for the studied antibiotics. The applicability of the method was demonstrated using various environmental and reclaimed water matrices. Erythromycin was detected in more than 85 % of the samples in all matrices (28–414, n.d.–199, n.d.–66 ng/L in reclaimed, river and drinking waters respectively). The other frequently detected antibiotics in reclaimed waters were nalidixic acid, clarithromycin, azithromycin, trimethoprim, and sulfamethoxazole.     

Determination of organochlorine pesticides (OCPs) in breast milk from Rio Grande do Sul,Brazil, using a modified QuEChERS method and gas chromatography-negative chemical ionisation-mass spectrometry

ABSTRACT

The food chain is the main source of exposure to humans by organochlorine pesticides (OCPs) due to the bioaccumulation. Breast milk can accumulate OCPs, so this matrix is often used as an environmental bioindicator. The currently available methods for the determination of several OCPs and metabolites in breast milk involve, in general, multi-step sample preparation and quantification techniques with low selectivity, high cost and much time and labour. Thus, a fast and efficient method based on sample preparation using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with gas chromatography coupled to mass spectrometry with negative chemical ionisation (GC-NCI-MS) was developed, validated and applied for determination of 16 OCPs and metabolites in breast milk samples. The extract was cleaned by dispersive solid-phase extraction (d-SPE) using MgSO₄ and C18, evaporated in a Turbovap® system, redissolved and analysed by GC-NCI-MS. The method was validated showing acceptable recoveries (72–118%) and precision (RSD <19%). Method limits of detection (LODs) and quantification (LOQs) ranged from 0.75 to 7.5 ng g^?1 and from 2.5 to 25 ng g^?1 lipid, respectively. The method was successfully applied to 20 samples of breast milk from different regions of the Rio Grande do Sul state, Brazil, of which 75% contained residues below the LOQs.     

Validation studies for multicomponent quantitative NMR analysis: the example of apple fruit juice

Laboratories intending to work as official laboratories for food control have to be accredited according to ISO/IEC 17025. This necessitates the use of validated analytical methods. In this study, we present validation results of the recently commercialized “JuiceScreener” based on nuclear magnetic resonance (NMR) spectroscopy with apple juice as application example. The quantitative analysis included 29 compounds such as major sugars, amino acids, organic acids, as well as acetoin, arbutin, benzaldehyde, hydroxymethylfurfural, acetaldehyde, methanol, and ethanol. Limit of detection (LOD), limit of quantification (LOQ), coefficients of variation (CV) for replicated measurements, repeatability, linear range, and recoveries were determined. The LOD and LOQ values varied in the 0.48–16 mg/L and in the 1.9–122 mg/L ranges with the lowest values for shikimic acid and highest for the principal sugars. The ¹H NMR assays were linear in broad concentration ranges (R > 0.99), encompassed typical concentration in apple juices, and are sufficient to control the requirements of the code of practice of the European fruit juice association. Recoveries between 92 and 109 % on average for five separate standard additions were obtained. The average CVs were found to be 3.0 % (intraday) and 3.6 % (interday) excluding sample preparation (by measuring five time one solution) and 5.5 % (intraday) and 6.2 % (interday) including sample preparation (by preparing and analyzing five separate samples). The NMR method was judged as suitable for the simultaneous quantification of compounds in apple juice for official food control purposes. Our results show that multiparameter NMR methods can be successfully validated with standard instrumentarium and that they are fit for the purpose of official food control.     

An SPE Method for the Concurrent Extraction of Organochlorine and Phenoxy Acidic Pesticides in River Water

We present the validation of a multiresidue method for the concurrent SPE of organochlorine (OCP) and phenoxy-acidic pesticides (PA) in river water. The two classes of compounds show very different chemical characteristics. The analyses were performed by gas chromatography?Cmass spectrometry and by liquid chromatography?Celectrospray ionization?Cmass spectrometry. The method was validated at three different concentrations: method limit of quantitation, 0.5 and 5 ??g L^?1. The recoveries were in the range 65?C135% for all the target compounds and in the range 83?C113% with RSD <20% for most of them at all the concentrations tested. The method showed good accuracy, precision, and sensitivity, and allowed the analysis of the selected pesticides at a concentration lower than that required by the EU current legislation for surface water [1]. The single-step procedure reduced artifacts, matrix effects, and speeded up sample preparation.     

Analysis and validation of perfluorinated compounds in water,sediment and fish with LC-ESI–MS/MS

The analysis of perfluorinated compounds (PFCs) in environmental matrices is challenging, as the concentrations are generally low, but the risk of contamination is high. Sample preparation is a critical step and it is necessary to minimise the possibility of contamination. In this study, we successfully applied and validated a modified ion pair extraction method to quantify PFCs in sediment and fish samples. A large volume injection method was validated and used to quantify PFCs in different water matrices. Isotope internal standard of every analyte was applied to correct matrix effects. The recoveries of the analytes were 92–106% for water matrix, 93–119% for fish matrix and 86–103% for soil matrix whereas the achieved limit of quantitation values were 1.3–14.9 ng/L for water, 0.19–0.28 μg/kg for fish and 0.14–0.41 for soil samples. Thirty-one surface water, 8 stormwater and 41 sediment samples collected all over Estonia were analysed and 4 (out of 8 analysed) PFCs were found in quantitative amount. The most frequently detected analyte perfluorobutanoic acid (PFBA) was found in 26% of the water samples with a maximum concentration of 137 ng/L.     

Highly Sensitive Determination of Butyl Xanthate in Surface and Drinking Water by Headspace Gas Chromatography with Electron Capture Detector

A highly sensitive and convenient method for the determination of butyl xanthate in surface water and drinking water was developed by headspace gas chromatography with electron capture detector (HS–GC–ECD). The analytical method was based on the decomposition of butyl xanthate under an acidic condition, generating carbon disulfide, which could be sensitively detected by gas chromatography with electron capture detector. The signal of CS₂ from the decomposition of potassium butyl xanthate was directly proportional to the concentration of potassium butyl xanthate over the range 0.7–100 ng/mL. The detection limit at a signal-to-noise ratio of three (S/N = 3) for potassium butyl xanthate was 0.3 ng/mL (~1.6 × 10⁻⁹ mol/L), which was more than two orders of magnitude lower than the popular UV methods and close to one order of magnitude lower than the similar headspace gas chromatography–mass spectroscopy method. The relative standard deviation (R.S.D.) within a day and in 3 days for potassium butyl xanthate at both 5 and 50 ng/mL was less than 4.7 %, suggesting good analytical performance of the present method. Good recoveries from 93.3 to 104.7 % were obtained from spiked surface and drinking water samples, indicating that the proposed HS–GC–ECD method was applicable for the quantification of butyl xanthate in surface and drinking water. Compared with other reported methods, the present method is highly sensitive, without sample preparation, and easily extended to the analysis of other xanthates.

     

Development and validation of a (semi-)quantitative UHPLC-MS/MS method for the determination of 191 mycotoxins and other fungal metabolites in almonds, hazelnuts, peanuts and pistachios

A multi-target method for the determination of 191 fungal metabolites in almonds, hazelnuts, peanuts and pistachios was developed. The method includes all mycotoxins regulated in the European Union and mycotoxins regularly found in food. After extraction with an acidified acetonitrile water mixture, the raw extract was diluted and injected directly into the UHPLC-MS/MS system. In two chromatographic runs, analysis was performed in positive and in negative ionisation mode. The method was in-house validated for the most important 65 analytes in these four commodities. Apparent recoveries between 80 and 120 % were obtained for about half of the analyte–matrix combinations. Good repeatabilities (standard deviations?<?10 %) were achieved for the vast majority (83 %) of all cases. Only in 6 % of all combinations did the standard deviations exceed 15 %. Matrix effects, arising during electrospray ionisation, significantly influenced the determination. For instance, signal suppression was observed for several early-eluting analytes and also signal enhancement up to 295 % for physcion in peanuts was determined. Concerning extraction recovery, 94 % of the analyte–matrix combinations showed values higher than 50 %. Lower limits of quantification ranged between 0.04 μg?kg^?1 for enniatin B3 in peanuts and 500 μg?kg^?1 for HC toxin in hazelnuts. Additionally, the applicability of the developed method was demonstrated through the analysis of 53 naturally contaminated nut samples from Austria and Turkey. Overall, 40 toxins were quantified; the most frequently found mycotoxins were beauvericin (79 %), enniatin B (62 %) and macrosporin (57 %). In the most contaminated hazelnut sample, 26 different fungal metabolites were detected.     

Simultaneous extraction and determination of pharmaceuticals and personal care products (PPCPs) in river water and sewage by solid-phase extraction and liquid chromatography-tandem mass spectrometry

This study features the simultaneous extraction and quantification of 18 pharmaceuticals and personal care products (PPCPs). This is a pioneering method for the quantification of acetaminophen, sulfamethoxazole, diclofenac, atenolol, metoprolol, diethyltoluamide and oxybenzone in atmospheric pressure chemical ionisation mode. The method was validated for high repeatability and reproducibility with relative standard deviations less than 10%. Instrument quantification limits for PPCPs were within the range of 0.05–1.0 µg L^?1, and the method quantification limits (MQLs) for ultrapure water were within the range of 0.3–15 ng L^?1. All samples were extracted using Oasis© hydrophilic–lipophilic balanced cartridges with optimised sample size and extraction conditions. Good accuracy was demonstrated, with solid-phase extraction recoveries above 80% for most PPCPs. In environmental matrices, the MQLs for river water, sewage treatment plant (STP) effluent and STP influent were 4–25, 10–153 and 38–386.5, respectively. The method was successfully applied to investigate occurrences of persistent PPCPs in Malaysian river and sewage samples.     

Solid-phase extraction and field-amplified sample injection–capillary zone electrophoresis for the analysis of benzophenone UV filters in environmental water samples

A field-amplified sample injection–capillary zone electrophoresis (FASI-CZE) method for the analysis of benzophenone (BP) UV filters in environmental water samples was developed, allowing the separation of all compounds in less than 8 min. A 9- to 25-fold sensitivity enhancement was obtained with FASI-CZE, achieving limits of detection down to 21–59 μg/L for most of the analyzed BPs, with acceptable run-to-run and day-to-day precisions (relative standard deviations lower than 17 %). In order to remove water sample salinity and to enhance FASI sensitivity, an off-line solid-phase extraction (SPE) procedure using a Strata X polymeric reversed-phase sorbent was used and afforded recoveries up to 72–90 % for most BPs. With the combination of off-line SPE and FASI-CZE, limits of detection in the range 0.06–0.6 μg/L in a river water matrix, representing a 2,400- to 6,500-fold enhancement, were obtained. Method performance was evaluated by quantifying a blank river water sample spiked at 1 μg/L. For a 95 % confidence level, no statistical differences were observed between found concentrations and spiked concentrations (probability at the confidence level, p value, of 0.60), showing that the proposed off-line SPE-FASI-CZE method is suitable for the analysis of BP UV filters in environmental water samples at low microgram per liter levels. The method was successfully applied to the analysis of BPs in river water samples collected up- and downstream of industrialized and urban areas, and in some drinking water samples.     

Validation of QuEChERS-based UPLC-MS/MS method for determination of quinoid niclosamide (LDS) residue in water,soil and rice samples

A sensitive, rapid and easy analytical method was validated for the determination of quinoid niclosamide (LDS) molluscicide in water, rice and soil using a QuEChERS extraction procedure and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection. The LDS was extracted by using acetonitrile and then cleaned up by using dispersive solid-phase extraction with florisil and C18 sorbents. The determination of the target compound was achieved in less than 3 min using an electrospray ionisation source in negative mode. The overall average recoveries for this method in water, rice and soil matrix at three fortified levels ranged from 82.54 to 99.9%, with relative standard deviations in the range of 1.51 to 4.86% (n = 5). The calculated limits of detection were lower than 0.1 µg kg^?1 and quantification was 5 µg kg^?1; these values were much lower than the maximum residue levels established by the Australian standard (0.01 mg kg^?1). The results of the method validation confirmed that this proposed method is convenient and reliable for the determination of LDS molluscicide in water, rice and soil samples.     

QuEChERS sample preparation followed by ultra-performance liquid chromatography – tandem mass spectrometry for rapid screening of dioctyl sulfosuccinate sodium salt in avian egg tissue

A quantification method was developed for the determination of dioctyl sulfosuccinate sodium salt (DOSS) in avian egg samples based on a QuEChERS extraction technique followed by UPLC-MS/MS analysis. DOSS is an anionic surfactant that is part of the Corexit^® 9500 dispersive mixture that prevents the formation of oil slicks on water bodies. It was extensively used when the Deepwater Horizon rig exploded and a large amount of crude oil was released into the Gulf of Mexico. QuEChERS provided a simple, effective and time saving sample preparation method prior to analysis without reducing analytical sensitivity and became an excellent substitute to lengthy traditional extraction methods. Weak anionic exchange cleanup significantly reduced matrix effects and improved analyte sensitivity. Ultra-performance liquid chromatography provided an effective separation method, while MS/MS provided the necessary selectivity and increased sensitivity. Our method achieved baseline separation of DOSS, surrogate (sodium octyl sulfate – d17) and the internal standard (sodium dioctyl sulfate – d25), with limits of detection (LOD) and limits of quantitation (LOQ) for DOSS being 260 and 500 pg/mL, respectively. Quality control recoveries were 70.5 ± 7.3% (mean ± standard deviation, n = 3) for the laboratory control sample and 72.4 ± 4.9% (n = 3) for the matrix spike. The extraction efficiency was monitored by adding surrogate compound to every sample with recoveries of 104.6 ± 14.1 for SDS-d1 and 81.8 ± 6.8 for SOS-d17. Currently, limited peer reviewed scientific data are reported on the effects of oil dispersants on the environment. Our analytical method for the determination of DOSS in avian egg matrix can be used to provide reliable data on the fate and effects of DOSS in biological systems.     

A multiresidue method for the determination of 109 pesticides in rice using the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography/mass spectrometry with temperature control and vacuum concentration

A rapid, specific and sensitive multiresidue method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with mass spectrometric detection by selected ion monitoring (GC/MS-SIM) has been developed for the routine analysis of 109 pesticides in rice. The method uses one quantification ion and two identification ions. Temperature control during sample preparation helps improve the recovery of thermally labile pesticides such as captan. The method was validated by the analysis of samples spiked at 0.025-0.150 mg/kg in rice matrix. The recoveries of all pesticides were between 80% and 115% with a relative standard deviation of less than 15%. The limit of quantitation (LOQ) for most compounds met the maximum residue limits (MRLs) for pesticides in rice in Korea.     

Determination of 19 Preservatives in Various Matrices by High-Performance Liquid Chromatography

A simple and sensitive high-performance liquid chromatography (HPLC) method was developed for the determination of 19 preservatives in cosmetic matrices. The composition of the mobile phase was optimized as a gradient to achieve a lower detection limit when compared to previously validated methods, and sample preparation conditions were investigated to optimize separation of the 19 preservatives. A C18 column was used with methanol, 0.05 mol/L ammonium acetate buffer, and water as the mobile phase under gradient elution conditions. Preservatives in cosmetics were extracted with 70% methanol using an ultrasonicator, after which they were analyzed with an HPLC-photodiode array detector. All preservatives were separated within 55 min. The recoveries ranged from 94.9% to 102.8%, with relative standard deviations of less than 3.2% and no correlation coefficients lower than 0.9986. Additionally, the developed method has a low detection limit, which makes it possible to analyze trace levels of compounds in various cosmetic and ingredient matrices.     

Wide-scope analysis of veterinary drug and pesticide residues in animal feed by liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry

A fast and generic method has been developed for the simultaneous monitoring of >250 pesticides and veterinary drugs (VDs) in animal feed. A ‘dilute-and-shoot’ extraction with water and acetonitrile (1 % formic acid) followed by a clean-up step with Florisil cartridges was applied. The extracts were analysed by ultra-high performance liquid chromatography coupled to hybrid analyser quadrupole-time-of-flight mass spectrometry using both positive and negative electrospray ionisation. The detection of the residues was accomplished by retention time and accurate mass using an in-house database. The identification of the detected compounds was carried out by searching of fragment ions for each compound and isotopic pattern. The optimised method was validated and recoveries ranged from 60 % to 120 % at three concentrations (10, 50 and 100 μg kg^?1) for 30 %, 68 % and 80 % of compounds, respectively, included in the database (364) in chicken feed. Document SANCO 12495/2011 and Directive 2002/657/CE were used as guidelines for method validation. Intra-day and inter-day precisions, expressed as relative standard deviations, were lower than 20 % for more than 90 % of compounds. The limits of quantification ranged from 4 to 200 μg kg^?1 for most analytes, which are sufficient to verify compliance of products with legal tolerances. The applicability of the procedure was further tested on different types of feed (chicken, hen, rabbit and horse feed), evaluating recoveries and repeatability. Finally, the method was applied to the analysis of 18 feed samples, detecting some VDs (sulfadiazine, trimethoprim, robenidin and monensin Na) and only one pesticide (chlorpyrifos).     

Rapid QuEChERS Approach Using Novel Solid Phase Extraction for Insecticides in Lobster and Shellfish Tissue with Gas Chromatography–Tandem Mass Spectrometry

Novel, rapid, inexpensive, and simple QuEChERS extraction followed by phospholipid solid phase extraction was successfully developed and validated for the determination of methoprene, resmethrin, bifenthrin, cyhalothrin, and permethrin in lobster and shellfish tissues by gas chromatography–tandem mass spectrometry. This method is equivalent in final sample purity to the traditional gel permeation and open column chromatography sample preparation techniques, but has clear advantages due to reductions in time, labor, solvent use, and can be performed with minimal staff training. The proposed methodology was effectively applied to the analysis of North Atlantic lobster (hepatopancreas and muscle) and shellfish tissue. The linearity of the calibration curves for all analytes were R² > 0.9991. The surrogate recoveries were 98.2 ± 18.0%, while the target compound recoveries, for fortified samples, were in the range of 62.0%–128.8% with RSD values <17.2% for all compounds. The detection limits for the analytes ranged from 0.0056 µg/g to 0.76 µg/g with 84.4–119.5% accuracy and relative standard deviations less than 3.77%.