E. Bizkarguenaga

Solid-phase extraction combined with large volume injection-programmable temperature vaporization-gas chromatography-mass spectrometry for the multiresidue determination of priority and emerging organic pollutants in wastewater.

In the present work the simultaneous extraction for the multiresidue determination in wastewater samples of organic compounds such as polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), pesticides, polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PEs), alkylphenols (APs), bisphenol A (BPA) or hormones included in different lists of priority and emerging pollutants because of their action as endocrine disrupting compounds (EDCs) was developed. Different solid phase extraction (SPE) variables such as the nature of the solid phase (Oasis-HLC, C18 and Lichrolut), the sample volume, the addition of MeOH and NaCl, the pH of the water phase and the volume of the eluent solvent were optimized in order to analyze simultaneously the priority and emerging families of pollutants mentioned above. Good recoveries were obtained for Milli-Q water (80-120%), however, since the use of deuterated analogues and dilution of the sample did not correct the matrix effect, additional SPE clean-up step using Florisil® cartridges was necessary to obtain good results for wastewater samples (80-125%). In order to improve the limits of detection (LODs), large volume injection (LVI) using programmable temperature vaporizer (PTV) coupled to gas chromatography-mass spectrometry (GC-MS) was also optimized. Since analytes losses in the case of the most volatile congeners occurred during the derivatization step and no separation of the derivatized and the non-derivatized analytes was possible during SPE elution, two different injections were optimized for each analyte group. LODs were in good agreement with those found in the literature and relative standard deviations (RSDs) were in the 10-25% range for Milli-Q and 12-30% for wastewater samples. The method was finally applied to the determination of target analytes in three different wastewater treatment plants (WWTPs, Bakio, Gernika and Galindo (Spain)) and in one water purification plant (WPP) in Zornotza (Spain).

Focused ultrasound solid–liquid extraction for the determination of perfluorinated compounds in fish, vegetables and amended soil

In the present work a method was developed for the determination of different perfluorinated compounds (PFCs), including three perfluorinated sulfonic acids (PFSAs), seven perfluorocarboxylic acids (PFCAs), three perfluorophosphonic acids (PFPAs) and perfluorooctanesulfonamide (PFOSA) in fish, vegetables and amended soil samples based on focused ultrasound solid-liquid extraction (FUSLE) followed by solid-phase extraction (SPE) clean-up and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Different variables affecting the chromatographic separation (column type and pH of the mobile phase), the electrospray ionization (capillary voltage, nebulizer pressure and drying gas flow) and mass spectrometric detection (fragmentor voltage and collision energy) were optimized in order to improve the sensitivity of the separation and detection steps. In the case of FUSLE variables such as the solvent type, the solvent volume, the extraction temperature, the sonication and extraction time and the percentage of applied irradiation power were studied. Under optimized conditions, sonication of 2.5min with pulse times on of 0.8s and pulse times off of 0.2s in 7mL of (9:1) acetonitrile (ACN): water mixture in duplicate guaranteed exhaustive extraction of the matrices analyzed. Due to the non-selective extraction using FUSLE, different SPE cartridges (200-mg Waters Oasis-HLB, 150-mg Waters Oasis-WAX and 150-mg Waters Oasis-MAX) were tested in terms of extraction efficiency and matrix effect both in the extraction and detection steps. Mix mode SPE using Waters Oasis-WAX provided the best extraction efficiencies with the lowest matrix effect. The final method was validated in terms of recovery at two fortification levels (in the 80-120% for most of the analytes and matrices), precision (relative standard deviation in the 2-15% range) and method detection limits (MDLs, 0.3-12.4ng/g for vegetables, 0.2-12.5ng/g for fish and 1-22ng/g for amended soil). Finally the method was applied for the determination of the 14 PFCs in different vegetables and fish samples from a local supermarket and in a soil amended with a compost from a local wastewater treatment plant (WWTP).

Simultaneous determination of a variety of endocrine disrupting compounds in carrot, lettuce and amended soil by means of focused ultrasonic solid–liquid extraction and dispersive solid-phase extraction as simplified clean-up strategy

The present study is focused on the development of an analytical method based on focused ultrasonic solid-liquid extraction (FUSLE) followed by dispersive solid-phase extraction (dSPE) clean-up and liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) optimised for the simultaneous analysis of certain endocrine disrupting compounds (EDCs), including alkylphenols (APs), bisphenol A (BPA), triclosan (TCS) and several hormones and sterols in vegetables (lettuce and carrot) and amended soil samples. Different variables affecting the chromatographic separation, the electrospray ionisation and mass spectrometric detection were optimised in order to improve the sensitivity of the separation and detection steps. Under the optimised extraction conditions (sonication of 5min at 33% of power with pulse times on of 0.8s and pulse times off of 0.2s in 10mL of n-hexane:acetone (30:70, v:v) mixture using an ice bath), different dSPE clean-up sorbents, such as Florisil, Envi-Carb, primary-secondary amine bonded silica (PSA) and C18, or combinations of them were evaluated for FUSLE extracts before LC-MS/MS. Apparent recoveries and precision in terms of relative standard deviation (RSDs %) of the method were determined at two different fortification levels (according to the matrix and the analyte) and values in the 70-130% and 2-27% ranges, respectively, were obtained for most of the target analytes and matrices. Matrix-matched calibration approach and the use of labelled standards as surrogates were needed for the properly quantification of most analytes and matrices. Method detection limits (MDLs), estimated with fortified samples, in the ranges of 0.1-100ng/g for carrot, 0.2-152ng/g for lettuce and 0.9-31ng/g for amended soil were obtained. The developed methodology was applied to the analysis of 11 EDCs in both real vegetable bought in a local market and in compost (from a local wastewater treatment plant, WWTP) amended soil samples.

Simultaneous determination of perfluorinated compounds and their potential precursors in mussel tissue and fish muscle tissue and liver samples by liquid chromatography-electrospray-tandem mass spectrometry.

An analytical method for the simultaneous determination in fish liver and muscle tissue and mussel samples of 14 perfluorinated compounds (PFCs), including three perfluoroalkylsulfonates (PFSAs), seven perfluorocarboxylic acids (PFCAs), three perfluorophosphonic acids (PFPAs) and perfluorooctanesulfonamide (PFOSA), and 10 potential precursors, including four polyfluoroalkyl phosphates (PAPs), four fluorotelomer saturated acids (FTCAs) and two fluorotelomer unsaturated acids (FTUCAs), was developed in the present work. Different clean-up strategies by means of solid-phase extraction (SPE) using a mix-mode weak anion exchanger (WAX), reverse phase Envi-Carb or a combination of them was optimized and evaluated for the clean-up of focused ultrasonic solid-liquid (FUSLE) extracts before the analysis by liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS). Mix-mode WAX coupled in-line to Envi-Carb was finally selected since it rendered the cleanest extracts and minimum matrix effect. The FUSLE-SPE-LC-MS/MS methodology was validated in terms of recovery, precision and method detection limits (MDLs). Apparent recovery values in the 65-116%, 59-119% and 67-126% range and MDLs in the 0.1-2.7 ng/g, 0.1-3.8 ng/g and 0.2-3.1ng/g range were obtained for liver, mussel and fish muscle tissue samples, respectively. The method developed was applied to the analysis of grey mullet liver (Chelon labrosus) and mussel (Mytilus galloprovincialis) samples from the Basque Coast (North of Spain) and Yellowfin tuna muscle tissue (Thunnus albacares) samples from the Indian Ocean. To the best of our knowledge this is the first method that describes the simultaneous determination of 14 PFCs and 10 potential precursors in fish liver, fish muscle tissue and mussel samples. Besides, this is the first time that 8:2 monosubstituted polyfluorodecyl phosphate (8:2 monoPAP) and 8:2 disubstituted polyfluorodecyl phosphate (8:2 diPAP) were detected in mussel and tuna samples, respectively.

Development of stir-bar sorptive extraction–thermal desorption–gas chromatography–mass spectrometry for the analysis of musks in vegetables and amended soils

The aim of this study was to develop a sensitive and environment-friendly method based on stir-bar sorptive extraction (SBSE) followed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) to determine 8 synthetic musks (musk ambrette, musk ketone, celestolide, tonalide, galaxolide, phantolide, traseolide, and cashmeran) in vegetables (lettuce, carrot, and pepper) and amended soil samples. In a first step sorptive extraction was studied both in the headspace (HSSE) and in the immerse mode (SBSE). The best results were obtained in the immersion mode which was further studied. The influence of the main factors: methanol (20%) and NaCl addition (0%), extraction temperature (40°C) and time (180 min), extraction solvent volume (9 mL) and stirring rate (600 rpm) on the efficiency of SBSE was evaluated by means of experimental designs. In the case of TD, desorption time (10 min), desorption temperature (300°C), cryo-focusing temperature (-30°C), vent flow (75 mL/min) and vent pressure (7.2 psi) were studied using both a fractioned factorial design and a central composite design (CCD). The method was validated in terms of apparent recoveries (AR%), method detection limits (MDLs) and precision at two different concentration levels. Although quantification using instrumental calibration rendered odd results in most of the cases, satisfactory recoveries (74-126%) were obtained in the case of matrix-matched calibration approach for all of the analytes and matrices studied at the two concentration levels evaluated. MDLs in the range of 0.01-0.8 ng/g and 0.01-1.1 ng/g were obtained for vegetables and amended soil samples, respectively. RSD values within 1-23% were obtained for all the analytes and matrices. Finally, the method was applied to the determination of musks in vegetable and amended soil samples.

In-port derivatization after sorptive extractions

Derivatization is necessary when analysis of polar compounds containing hydroxyl, carboxylic acid, amine or thiol functional groups is accomplished by gas chromatography (GC), in order to improve peak symmetry, peak separation and detector response. Derivatization can be performed off-line in a reaction vessel that is separated from the GC analysis hardware. However, on-line derivatization can eliminate time-consuming sample-processing steps, decrease the amount of valuable and/or toxic reagents and solvents that are used off-line, as well as increase the speed and efficiency of the analysis performed. The present work revises on-line in-port derivatizations where the derivatization reaction is simultaneously carried out with the analysis step by injecting the sample/reagent mixture directly into the hot GC inlet after a sorptive extraction step. Sorptive extractions revised range from the more classical solid-phase extraction (SPE) to the microextraction approaches, including solid-phase microextraction (SPME) and stir-bar sorptive extraction (SBSE) applications, as well as liquid-phase microextraction (LPME) or microextraction by packed sorbent (MEPS).

Uptake of perfluorooctanoic acid, perfluorooctane sulfonate and perfluorooctane sulfonamide by carrot and lettuce from compost amended soil.

Sewage sludge, which acts like a sink for many pollutants, including metals, pathogens and organic pollutants, that are not completely removed in waste water treatment plants (WWTPs), is applied as a nutrient rich organic fertilizer in many agricultural applications. In the present work, carrot and lettuce crops were grown in two different compost amended soils fortified with perfluorooctanoic acid (PFOA), perfluorosulfonate acid (PFOS) and perfluorosulfonamide (FOSA) and cultivated in a greenhouse. The plants were harvested and divided into root core, root peel and leaves in the case of carrots and into heart and leaves for lettuces. Concentrations for all the different compartments were determined to assess the bioconcentration factors (BCFs) and the plant distribution of the target analytes. The highest carrot BCFs for PFOA and PFOS were determined in the leaves (0.6-3.4), while lower values were calculated in the core (0.05-0.6) and the peel (0.05-1.9) compartments. However, PFOA was taken up in the translocation stream and accumulated more than PFOS in the edible part of lettuce. FOSA was totally degraded in the presence of carrot; however, a lower FOSA degradation was observed in presence of the lettuce, which was dependent on the total organic carbon (TOC) content of the soil. The higher the TOC value, the higher the FOSA degradation observed. No degradation was observed in the crop absence. In the case of the carrot experiments, different polymeric materials (polyethersulfone, PES, polyoxymethylene, and silicone rod) were tested to predict the concentration in the cultivation media. A high correlation (r(2)>0.63) was observed for the BCFs in the PES and in the carrot core and peel for PFOA and PFOS. It could be, concluded that the PES can be used as a first approach for the determination of the uptake of compounds such as PFOS and PFOA in carrot.

Matrix solid-phase dispersion of polybrominated diphenyl ethers and their hydroxylated and methoxylated analogues in lettuce, carrot and soil ☆

In the present work, a novel analytical method for the simultaneous determination of ten polybrominated diphenyl ethers (PBDEs), eight methoxylated PBDEs (MeO-PBDEs) and seven hydroxylated PBDEs (OH-PBDEs) in soil, lettuce and carrot samples was developed. The procedure was based on matrix solid-phase dispersion (MSPD) followed by gas chromatography coupled to negative chemical ionization-mass spectrometry (GC-NCI-MS). Under optimum conditions, 0.5g of sample (freeze-dried in the case of lettuce and carrot samples) was dispersed with 0.5g of octadecyl-functionalized silica (C18) and 1.75g of acidified silica (10% H2SO4, w/w) was used as clean-up sorbent. A two-step fractionated elution was carried out. First, PBDEs and MeO-PBDEs were eluted in 75:25% (v/v) n-hexane/dichloromethane mixture and, then, the retained OH-PBDEs were eluted in pure dichloromethane. Both extracts were analyzed by GC-NCI-MS separately, in the case of OH-PBDEs after derivatization with N-methyl-N-(trimethylsilyl) trifluoroacetamide. The developed method was validated in terms of accuracy for soil, lettuce and carrot matrices, spiked at two fortification levels (5 and 25ngg(-1)). After correction with the corresponding surrogate, apparent recovery values (defined as the recovery obtained after correction with the corresponding surrogate) were in the 80-129% range. Precision (as relative standard deviation) in the 1-21% range and method detection limits (MDLs) in the 0.003 and 0.3ngg(-1) range for soil and in the 0.003-0.4ngg(-1) range (dry weight) for lettuce and carrot samples were obtained. For PBDEs the method was also validated with a standard reference material (SRM-2585) of house dust. Finally, the method was applied for the determination of target analytes in soil, lettuce and carrot.

Fast and simple determination of perfluorinated compounds and their potential precursors in different packaging materials.

A simple and fast analytical method for the determination of fourteen perfluorinated compounds (PFCs), including three perfluoroalkylsulfonates (PFSAs), seven perfluorocarboxylic acids (PFCAs), three perfluorophosphonic acids (PFPAs) and perfluorooctanesulfonamide (PFOSA) and ten potential precursors, including four polyfluoroalkyl phosphates (PAPs), four fluorotelomer saturated acids (FTCAs) and two fluorotelomer unsaturated acids (FTUCAs) in different packaging materials was developed in the present work. In order to achieve this objective the optimization of an ultrasonic probe-assisted extraction (UPAE) method was carried out before the analysis of the target compounds by liquid-chromatography-triple quadrupole-tandem mass spectrometry (LC-QqQ-MS/MS). 7 mL of 1 % acetic acid in methanol and a 2.5-min single extraction cycle were sufficient for the extraction of all the target analytes. The optimized analytical method was validated in terms of recovery, precision and method detection limits (MDLs). Apparent recovery values after correction with the corresponding labeled standard were in the 69-103 % and 62-98 % range for samples fortified at 25 ng/g and 50 ng/g concentration levels, respectively and MDL values in the 0.6-2.2 ng/g range were obtained. The developed method was applied to the analysis of plastic (milk bottle, muffin cup, pre-cooked food wrapper and cup of coffee) and cardboard materials (microwave popcorn bag, greaseproof paper for French fries, cardboard box for pizza and cinema cardboard box for popcorn). To the best of our knowledge, this is the first method that describes the determination of fourteen PFCs and ten potential precursors in packaging materials. Moreover, 6:2 FTCA, 6:2 FTUCA and 5:3 FTCA analytes were detected for the first time in microwave popcorn bags.

Focused ultrasound assisted extraction for the determination of PBDEs in vegetables and amended soil.

Focused-ultrasound solid-liquid extraction was developed for the extraction of polybrominated diphenyl ethers in vegetables and amended soil. Firstly, solid-phase extraction clean-up using 2g and 5 g of Florisil and 2-g silica cartridges were evaluated and elution profile was also optimised. Similar recoveries were obtained for most compounds while better recoveries were obtained for 5-g Florisil in the case of the heavier PBDEs. FUSLE extraction time (2 min) guaranteed quantitative extraction of the target analytes in the four studied matrices (69-130%). Method detection limit values were in the range of 1-5 ng g(-1) for splitless injection in a gas chromatograph coupled to a mass spectrometer and no significant improvement was obtained for large volume injection. Relative standard deviation values were between 1% and 30%. Recoveries obtained using FUSLE were compared with those obtained with microwave assisted extraction and the developed method was also applied to a certify reference material of polybrominated diphenyl ethers and polychlorinared biphenyls in sediment. Similar values were obtained in the case of carrot and pepper matrices (77-130% for FUSLE and 77-112% for MAE). However, MAE provided extraction recoveries higher than 100% for most of the BDE congeners in lettuce and amended soil.