Determination of Emerging Contaminants in Cereals by Gas Chromatography-Tandem Mass Spectrometry.

Cereals are staple foods for human consumption in both developed and developing countries. In order to improve agricultural outputs, resources like reclaimed water for irrigation and biosolids and manure as fertilizers are frequently used, although they may increase the input of contaminants that can potentially be absorbed by crops and enter the food chain. Emerging contaminants (human and veterinary pharmaceuticals, personal care products, surfactants, plasticizers, and industrial additives, among others) are continuously introduced in the environment from a variety sources and these contaminants may enter the food chain through plant uptake. In this study, an analytical method, based on ultrasound-assisted extraction and dispersive solid-phase cleanup, was developed for the determination of emerging contaminants from different classes in four highly consumed cereal grains (wheat, oat, barley, and rice). These analytes were selected considering the results of our previous studies carried out in soil and vegetables and those frequently detected in real samples were chosen. The target compounds selected were bisphenol A (BPA), bisphenol F (BPF), methyl paraben, propyl paraben, linear chain nonylphenol in position 4 (4-n-NP), mixture of ring and chain isomers of NP and six pharmaceutical compounds (allopurinol, mefenamic acid, carbamazepine, paracetamol, diclofenac and ibuprofen). Recoveries ranging from 68 to 119% with relative standard deviations (RSD) <18% were obtained for all the compounds except for allopurinol, with recoveries that ranged from 30 to 66% with RSD ≤ 12% and the limits of detection achieved ranged from 0.03 to 4.9 ng/g. The method was applied to the analysis of 16 cereal samples, ten were purchased in local supermarkets and the rest were collected directly from agricultural fields, five of which were fertilized with organic amendments. Bisphenol A (BPA) was detected in all samples at levels that ranged from 1.6 to 1,742 ng/g. Bisphenol F, a substitute for BPA, was also found in six samples (up to 22 ng/g). Linear 4-n-NP was found in a reduced number of samples but the mixture of NP isomers was found in all the samples, being the mean concentrations in wheat, barley, oat and rice 49, 90, 142, and 184 ng/g, respectively.

Molecularly imprinted polymer-hollow fiber microextraction of hydrophilic fluoroquinolone antibiotics in environmental waters and urine samples.

In the present work, the preparation of a new selective molecularly imprinted polymer (MIP) for the family of fluoroquinolones (FQs) in the pores of polypropylene hollow fibers (HFs) is proposed. The resulting MIP-HFs, which combine solid-phase microextraction (SPME) and molecular imprinting technologies, were used to develop a selective microextraction methodology (MIP-HFM) to determine selected FQs danofloxacin, norfloxacin, enrofloxacin and ciprofloxacin in real samples of environmental and biological interest. Measurements during the optimization of the MIP-HFM and its application to the analyses of real samples were performed by HPLC-UV and HPLC-MS/MS. In order to establish optimum rebinding conditions, the effect of key experimental parameters such as loading media, extraction time and stirring-rate were studied. The developed MIP composites exhibited recognition properties towards the selected hydrophilic antibiotics in non-polar media (toluene) and in polar protic systems such as methanol and methanol/water solutions, up to 20% water content. Recoveries by the developed method for all FQs tested in surface water, groundwater and urine spiked with the analytes of interest at two different concentration levels were within 9.4-24.5 %, with a relative standard deviation, generally <20% (n = 3). The detection limits were within 0.1-10 µg L-1, depending upon the antibiotic and the type of sample.

Analysis of emerging organic contaminants in poultry manure by gas chromatography-tandem mass spectrometry.

A multiresidue method was developed for the determination of 19 emerging organic contaminants (pharmaceutical drugs, personal care products, and bisphenol A) in poultry manure. Lyophilized samples of manure were extracted by ultrasound-assisted matrix solid-phase dispersion and the extracts were analyzed by gas chromatography with tandem mass spectrometry after derivatization. Analysis of spiked poultry manure samples, at levels ranging from 25 to 150 ng/g, gave satisfactory recovery results for all the compounds, with values from 67 to 106%. The developed procedure provided detection limits that ranged from 0.9 to 2.2 ng/g. Finally, the validated method was applied to poultry manure samples collected from 23 poultry farms in Spain. Salicylic acid was found in most of the samples analyzed at levels up to 2501 ng/g, whereas, methyl paraben, orthophenylphenol, ibuprofen, paracetamol, and carbamazepine were detected at levels up to 250 ng/g. Composting of manure showed an important decrease in the levels of the detected contaminants.

Determination of endocrine-disrupting compounds in water samples by magnetic nanoparticle-assisted dispersive liquid-liquid microextraction combined with gas chromatography-tandem mass spectrometry.

A rapid extraction procedure is presented for the determination of five endocrine-disrupting compounds, estrone, ethinylestradiol, bisphenol A, triclosan, and 2-ethylhexylsalicylate, in water samples. The analysis involves a two-step extraction procedure that combines dispersive liquid-liquid microextraction (DLLME) with dispersive micro-solid phase extraction (D-µ-SPE), using magnetic nanoparticles, followed by in situ derivatization in the injection port of a gas chromatograph coupled to triple quadrupole mass spectrometry. The use of uncoated or oleate-coated Fe3O4 nanoparticles as sorbent in the extraction process was evaluated and compared. The main parameters involved in the extraction process were optimized applying experimental designs. Uncoated Fe3O4 nanoparticles were selected in order to simplify and make more cost-effective the procedure. DLLME was carried out at pH 3, during 2 min, followed by the addition of the nanoparticles for D-µ-SPE employing 1 min in the extraction. Analysis of spiked water samples of different sources gave satisfactory recovery results for all the compounds with detection limits ranging from 7 to 180 ng l-1. Finally, the procedure was applied in tap, well, and river water. Graphical abstract Diagram of the extraction method using magnetic nanoparticles (MNPs).

Application of magnetic iron oxide nanoparticles for the analysis of PCBs in water and soil leachates by gas chromatography-tandem mass spectrometry.

Two magnetic solid-phase extraction methods (mSPE) were developed and compared for the extraction and preconcentration of polychlorinated biphenyls (PCBs) from water and soil leachates. Analyses were carried out by gas chromatography coupled to triple quadrupole mass spectrometry. The mSPE extraction parameters were optimised using Fe3O4 nanoparticles coated with palmitate or oleate. Differences were found between the developed mSPE methods depending on the magnetic nanoparticle coating. The extraction efficiency of both sorbents was studied by spiking soil leachates at three concentration levels (from 0.6 to 0.18 ng ml(-1) and from 0.4 to 0.04 ng ml(-1) using palmitate or oleate coated nanoparticles, respectively) and recoveries from 86 to 109 % were obtained. The developed method provided a preconcentration factor of 250. The detection limits were about 29 times lower with the oleate-coated nanoparticles. Although both mSPE procedures could be used for the extraction of PCBs from water and soil leachates, oleate-coated nanoparticles gave the best extractive conditions and lower quantifications limits. Finally, the mSPE using oleate-coated nanoparticles was applied to the analysis of PCBs in river waters and in soil leachates obtained from soil with different physico-chemical characteristics. The levels of PCBs present in the leachates depended on the soil sample. The present work demonstrates the applicability of both mSPE methods to the determination of PCBs in water and soil leachates, which is of interest for mobility and bioavailability studies of these compounds in soil.

Multiresidue analysis of insecticides and other selected environmental contaminants in poultry manure by gas chromatography/mass spectrometry.

An analytical method was developed for the simultaneous determination in poultry manure of 41 organic contaminants belonging to different chemical classes: pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated diphenyl ethers. Poultry manure was extracted with a modified QuEChERS method, and the extracts were analyzed by isotope dilution GC/MS. Recovery of these contaminants from samples spiked at levels ranging from 25 to 100 ng/g was satisfactory for all the compounds. The developed procedure provided LODs from 0.8 to 9.6 ng/g. The analysis of poultry manure samples collected on different farms confirmed the presence of some of the studied contaminants. Pyrethroids and polycyclic aromatic hydrocarbons were the main contaminants detected. DDT and its metabolite DDE were also found but at relatively low concentrations.

Rapid determination of natural and synthetic hormones in biosolids and poultry manure by isotope dilution GC-MS/MS.

The release of hormones into the environment due to land application of biosolids and manure is a cause of concern for their potential impacts. This paper presents the development of a rapid and sensitive method, based on extraction, for the analysis of 13 hormones in biosolids and poultry manure. A simultaneous derivatization of hydroxyl and ketone groups was carried out for the determination of hormones by GC­MS/MS. The method was validated in three matrices (sewage sludge, manure, and broiler litter). Recoveries from spiked samples at three concentration levels (50, 25, and 10 ng/g) ranged from 76 to 124% with relative SDs ≤ 16%. Method detection limits for the three matrices were in the range of 0.5­3.0 ng/g dry weight. The optimized method was applied to biosolid and poultry manure samples collected in Spain. Only seven of the 13 studied hormones were detected in the different samples. trans-Androsterone was detected at high levels (up to 3.1 µg/g in biosolid samples). Estrone and estradiol were the two hormones detected at higher levels in layer manure, whereas estrone and 4-androstene-3,17-dione presented the highest levels in broiler litter.

Determination of selected pharmaceutical compounds in biosolids by supported liquid extraction and gas chromatography-tandem mass spectrometry.

In this work, an analytical method was developed for the determination of pharmaceutical drugs in biosolids. Samples were extracted with an acidic mixture of water and acetone (1:2, v/v) and supported liquid extraction was used for the clean-up of extracts, eluting with ethyl acetate:methanol (90:10, v/v). The compounds were determined by gas chromatography-tandem mass spectrometry using matrix-match calibration after silylation to form their t-butyldimethylsilyl derivatives. This method presents various advantages, such as a fairly simple operation for the analysis of complex matrices, the use of inexpensive glassware and low solvent volumes. Satisfactory mean recoveries were obtained with the developed method ranging from 70 to 120% with relative standard deviations (RSDs) ≤ 13%, and limits of detection between 0.5 and 3.6 ng g(-1). The method was then successfully applied to biosolids samples collected in Madrid and Catalonia (Spain). Eleven of the sixteen target compounds were detected in the studied samples, at levels up to 1.1 µg g(-1) (salicylic acid). Ibuprofen, caffeine, paracetamol and fenofibrate were detected in all of the samples analyzed.

Analysis of natural-occurring and synthetic sexual hormones in sludge-amended soils by matrix solid-phase dispersion and isotope dilution gas chromatography-tandem mass spectrometry.

A sensitive analytical method is presented for the simultaneous determination of four synthetic estrogens and six steroid hormones in sludge-amended soil. The method employs matrix solid-phase dispersion (MSPD) followed by isotope dilution gas chromatography-tandem mass spectrometry injecting a large volume sample (10µL) after trimethylsilyl derivatization, using the solvent vent mode. It affords good resolution, high sensitivity and reproducibility and freedom from interferences even from complex matrices as soil amended with sewage sludge. The limits of detection (LODs) ranged from 10 to 300pgg(-1) with testosterone and progesterone having the highest limits. Soil amended with sewage sludge was spiked at 2, 10, 25 and 50ngg(-1) and the recoveries after MSPD with acetonitrile:methanol (90:10, v/v), ranged from 80 to 110% with relative standard deviations ≤9%. The method was applied to the analysis of six soil samples collected from agricultural plots and forested fields that had been amended with sewage sludge using isotopically labeled surrogates. Three of the synthetic estrogens studied were found at least in one of the six samples analyzed and trans-androsterone and estrone were the only natural hormones detected, although at very low levels (≤0.4ngg(-1)).

Gas chromatography-triple-quadrupole mass spectrometry for analysis of selected polyhalogenated pollutants in plants. Comparison of extraction methods.

Different extraction methods, followed by gas chromatography coupled to triple quadrupole mass spectrometry, were evaluated for simultaneous extraction of seven polychlorinated biphenyls (PCBs) and six polybrominated diphenyl ethers (PBDEs) from common weeds. Pressurized liquid extraction (PLE) with in-cell clean-up, ultrasound-assisted extraction (UAE) with in-column clean-up, and UAE with dispersive solid-phase extraction (dSPE) clean-up were evaluated and compared. In-cell clean-up with 4 g Florisil and 0.5 g graphitized carbon black (GCB) and two extraction cycles of 10 min with n-hexane-ethyl acetate 80:20 (v/v) at 60 °C were used for the PLE procedure. UAE with in-column clean-up was conducted under conditions similar to those reported for the PLE method whereas in UAE with dSPE clean-up purification of the extract was performed after extraction using primary and secondary amine sorbent (PSA) and GCB. Recovery from 82 to 104% was obtained for all the compounds by PLE whereas, in general, lower extraction efficiency was obtained by UAE with in-column clean-up (especially for BDE-17 and BDE-183, for which recovery was 70 and 41%, respectively) and by UAE with dSPE clean-up, for which the main drawback is that BDE-183 cannot be extracted. Finally, PLE was used for analysis of PCBs and PBDEs in different plants (Lolium rigidum, Lactuca serriola, Malva sylvestris, and Verbascum thapsus) collected from residential and/or rural areas of Madrid (Spain). Several of the analyzed compounds were detected at low levels in these plants, but only PCB-153 could be quantified.

Determination of selected organic contaminants in soil by pressurized liquid extraction and gas chromatography tandem mass spectrometry with in situ derivatization.

The determination of organic contaminants in soil is a real challenge due to the large number of these compounds with quite different physico-chemical properties. In the present work, an analytical method was developed for the simultaneous determination in soil of 40 organic contaminants belonging to different chemical classes: polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers, UV filters, parabens, bisphenols and triclosan. Soil was extracted by pressurized liquid extraction and the extracts, without the need of a clean-up step, were analyzed by gas chromatography-tandem mass spectrometry after in situ derivatization in the gas chromatographic system. In the pressurized liquid extraction step, two extraction cycles were performed with a mixture of ethyl acetate-methanol (90:10, v/v) at 80 °C. Recovery of these contaminants from soil samples spiked at levels ranging from 30 to 120 ng g(-1) was satisfactory for most of the compounds. The developed procedure provided detection method limits from 0.1 to 2.5 ng g(-1). The analysis of soil samples collected in different agricultural fields confirmed the presence of some of the studied contaminants. Polycyclic aromatic hydrocarbons were the main contaminants detected, parabens and polychlorinated biphenyls were also found but at relatively low concentration levels, 2-ethylhexyl salicylate was the UV filter that appeared most frequently at levels ranging from 17.2 to 43.4 ng g(-1) and triclosan was found in eight out of fourteen samples, at relatively low concentration levels (0.8-28.6 ng g(-1)).

Analysis of salicylate and benzophenone-type UV filters in soils and sediments by simultaneous extraction cleanup and gas chromatography-mass spectrometry.

An analytical method for the determination of UV filters in soil and sediment has been developed and validated considering benzophenones (BP) and salicylates as target analytes. Soil and sediment samples were extracted with ethyl acetate-methanol (90:10, v/v) assisted with sonication, performing a simultaneous clean-up step. Quantification of these compounds was carried out by gas chromatography-mass spectrometry (GC-MS) after derivatization of the extracts with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Recoveries from spiked soil samples ranged from 89.8% to 104.4% and they were between 88.4% and 105.3% for spiked sediment samples. The effect of the residence time and soil moisture content on the recovery of these compounds was also studied. The precision, expressed as relative standard deviation, was in all cases below 6.1% and the limits of detection (S/N=3) varied from 0.07 to 0.10 ng g(-1) and from 0.11 to 0.28 ng g(-1) for soils and sediments, respectively. The validated method was applied to the analysis of five benzophenone and two salicylate UV filters in soil and sediment samples collected in different areas of Spain.

Determination of cyclic and linear siloxanes in soil samples by ultrasonic-assisted extraction and gas chromatography-mass spectrometry.

A rapid method, based on sonication-assisted extraction in small columns (SAESC) and subsequent quantification and identification by gas chromatography-mass spectrometry (GC-MS), was developed for the determination of cyclic and linear siloxanes in soil. In the experiments with spiked samples (10-50 ng g(-1)), the recovery of cyclic and linear siloxanes ranged from 87.7 to 108.0% and from 84.9 to 107.6%, respectively. The validated method was used to determine the levels of these compounds in various types of soil samples collected from different locations in Spain. The cyclic siloxanes, decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) were detected in all the soil samples analyzed at concentrations from 9.2 to 56.9 ng g(-1) for D5 and from 5.8 to 27.1 ng g(-1) for D6 in agricultural soils and from 22 to 184 ng g(-1) for D5 and from 28 to 483 ng g(-1) for D6 in industrial soils. The total linear siloxanes concentrations (L5-L14) (sum of the 10 congeners) ranged from 191 to 292 ng g(-1) in agricultural soils and from 1411 to 8532 ng g(-1) in industrial soils.

Determination of triclosan and methyl triclosan in environmental solid samples by matrix solid-phase dispersion and gas chromatography-mass spectrometry.

In this study, a method for the determination of triclosan (TCS) and methyl triclosan (MTCS) in soil and sewage sludge samples from municipal wastewater treatment plants was developed based on the extraction by matrix solid-phase dispersion. After extraction, the analytes were derivatized with N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide for their determination by isotope dilution GC with electron impact MS detection in the SIM mode, using (13)C(12)-labeled compounds as internal standards. Recoveries of MTCS and TCS from laboratory spiked sludge samples were in the range from 95.7 to 101.0% and 97.4 to 101.3%, respectively. In the case of soil samples, the recoveries of MTCS and TCS ranged from 98.4 to 101.0% and 98.7 to 99.0%, respectively. The limits of detection (S/N=3) varied from 0.10 to 0.12 ng/g for sewage sludge samples and from 0.05 to 0.08 ng/g for soil samples. The validated method was used to assess the levels of TCS and MTCS in sewage sludge collected from 19 wastewater treatment plants located in Madrid (Spain) and in soil samples collected from agricultural fields in Madrid. Both compounds were detected in all the sludge samples at concentrations ranging from 54 to 2987 ng/g dry weight for TCS and from 4 to 311 ng/g dry weight for MTCS. The levels encountered in soil were much lower, 0.8 to 4.7 ng/g dry weight for TCS and 0.3 to 3.8 ng/g dry weight for MTCS.

Multiresidue determination of pesticides in juice by solid-phase extraction and gas chromatography-mass spectrometry.

A multiresidue method based on solid-phase extraction was developed for the simultaneous determination of 50 pesticides in commercial juices. The extraction procedure was carried out in C(18) columns preconditioned with acetonitrile and water. The subsequent elution of pesticides was performed with a mixture of hexane-ethyl acetate (1:1, v/v) prior to the determination by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM), using one target and two qualifier ions. Standards were prepared spiking blank juice samples to counteract the observed matrix effect. Average recoveries for all the pesticides studied were higher than 91% with relative standard deviations lower than 9% in the concentration range of 0.02-0.1mug/mL and the detection limits achieved ranged from 0.1 to 4.6mug/L. The proposed method was applied to the analysis of these compounds in commercial juices and diazinon, ethion and procymidone were the pesticides encountered, although the levels found were very low.

Analysis of pesticides in honey by solid-phase extraction and gas chromatography-mass spectrometry.

An analytical method for the simultaneous determination of 51 pesticides in commercial honeys was developed. Honey (10 g) was dissolved in water/methanol (70:30; 10 mL) and transferred to a C(18) column (1 g) preconditioned with acetonitrile and water. Pesticides were subsequently eluted with a hexane/ethyl acetate mixture (50:50) and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM). Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. Pesticides were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.1, 0.05, and 0.025 microg/g fortification levels for each pesticide, and the recoveries obtained were >86% with relative standard deviations of <10%. Good resolution of the pesticide mixture was achieved in approximately 41 min. The detection limits of the method ranged from 0.1 to 6.1 microg/kg for the different pesticides studied. The developed method is linear over the range assayed, 25-200 microg/L, with determination coefficients of >0.996. The proposed method was applied to the analysis of pesticides in honey samples, and low levels of a few pesticides (dichlofluanid, ethalfluralin, and triallate) were detected in some samples.

Determination of thiabendazole in orange juice and rind by liquid chromatography with fluorescence detection and confirmation by gas chromatography/mass spectrometry after extraction by matrix solid-phase dispersion.

A method was developed for the determination of thiabendazole (TBZ) in orange juice and rind based on matrix solid-phase dispersion (MSPD). TBZ was extracted with ethyl acetate and the extract was subsequently cleaned up on a solid-phase extraction column. Fungicide residues were determined by liquid chromatography with fluorescence detection. Recoveries through the method ranged from 87 to 97% with relative standard deviations < or = 11%. The detection and quantitation limits were 0.15 and 0.50 microg/kg, respectively. The confirmation of TBZ residues in positive samples was performed by solid-phase microextraction followed by gas chromatography with mass spectrometric detection using selected ion monitoring. The developed method was applied to determine TBZ levels in commercial orange juices and in juice and rind of fresh oranges. The influence of storage and washing of fruits on TBZ residues was also studied.

Multiresidue determination of pesticides in soil by gas chromatography-mass spectrometry detection.

An analytical multiresidue method for the simultaneous determination of various classes of pesticides in soil was developed. Pesticides were extracted from soil with ethyl acetate. Soil samples were placed in small columns, and the extraction was carried out assisted by sonication. Pesticides were determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode. Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. Pesticides were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.2, 0.1, and 0.05 microg/g fortification levels of each pesticide, and the recoveries obtained ranged from 87.0 to 106.2% with a relative standard deviation between 2.4 and 10.6%. Good resolution of the pesticide mixture was achieved in approximately 41 min. The detection limits of the method ranged from 0.02 to 1.6 microg/kg for the different pesticides studied. The developed method is linear over the range assayed, 25-1000 microg/L, with determination coefficients >0.999. The proposed method was used to determine pesticide levels in real soil samples, taken from different agricultural areas of Spain, where several herbicides and insecticides were found.

Determination of organophosphorus pesticides in fruit juices by matrix solid-phase dispersion and gas chromatography.

A rapid multiresidue method was developed for the determination of nine organophosphorus pesticides in fruit juices. The analytical procedure is based on the matrix solid-phase dispersion (MSPD) of juice samples on Florisil in small glass columns and subsequent extraction with ethyl acetate assisted by sonication. Residue levels were determined by gas chromatography with nitrogen-phosphorus detection. Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. The NPD response for all pesticides was linear in the concentration range studied with determination coefficients >0.999. Average recoveries obtained for all of the pesticides in the different juices and fortification levels were >70% with relative standard deviations of <11%. The detection limits ranged from 0.1 to 0.6 microg/kg. The identity of the pesticides was confirmed by gas chromatography with mass spectrometric detection using selected ion monitoring. The proposed MSPD method was applied to determine pesticide residue levels in fruit juices sold in Spanish supermarkets. At least one pesticide was found in most of the samples, although the levels detected were very low, far from the maximum residue levels established for raw fruit.

Determination of polycyclic aromatic hydrocarbons in honey by matrix solid-phase dispersion and gas chromatography/mass spectrometry.

A multiresidue method was developed for the de termination of 16 polycyclic aromatic hydrocarbons (PAHs) in unifloral and multifloral honeys. The analytical procedure is based on the matrix solid-phase dispersion of honey on a mixture of Florisil and anhydrous sodium sulfate in small glass columns and extraction with hexane-ethyl acetate (90 + 10, v/v) with assisted sonication. The PAH residues are determined by gas chromatography with mass spectrometric detection using selected-ion monitoring. Average recoveries for all the PAHs studied were in the range of almost 80 to 101%, with relative standard deviations of 6 to 15%. The limits of detection ranged from 0.04 to 2.9 microg/kg. The simultaneous extraction and cleanup of samples makes this method simple and rapid, with low consumption of organic solvents