Selective pressurized liquid extraction of polybrominated diphenyl ethers in fish

A fast and simple method for the analysis of polybrominated diphenyl ethers (PBDEs) in fish samples was developed using a one-step extraction and clean-up by means of pressurized liquid extraction (PLE) combined with gas chromatography-ion trap tandem mass spectrometry (GC-ITMS-MS). The selective PLE method provided to obtain ready-to-analyse extracts without any additional clean-up step, using a sorbent as fat retainer inside the PLE cell. Several PLE operating conditions, such as solvent type, extraction temperature and time, number of cycles and type of fat retainer, were studied. Using Florisil as fat retainer, maximum recoveries of PBDEs (83-108%) with minimum presence of matrix-interfering compounds were obtained using a mixture of n-hexane:dichloromethane 90:10 (v/v) as solvent, an extraction temperature of 100 °C and a static extraction time of 5 min in combination with three static cycles. Quality parameters of the method were established using standards and fish samples. Limits of detection and quantification ranged from 10 to 34 pg g⁻¹ wet weight and between 34 and 68 pg g⁻¹ wet weight, respectively. In addition, good linearity (between 1 and 500 ng ml⁻¹) and high precision (RSD % < 15%) were achieved. The method was validated using the standard reference material SRM-1945 (whale blubber) and was then applied to the analysis of PBDEs in fish samples.     

Simultaneous pressurized liquid extraction and clean-up for the analysis of polybrominated biphenyls by gas chromatography-tandem mass spectrometry

This paper describes a fast and simple pressurized liquid extraction (PLE) method combined with gas chromatography coupled to ion trap tandem mass spectrometry (GC-ITMS-MS) for the determination of polybrominated biphenyls (PBBs) in fish samples. The method is based on a simultaneous extraction/clean-up step to reduce analysis time and solvent consumption. The effect of several PLE operating conditions, such as solvent type, extraction temperature and time, number of cycles, and lipid retainer, was optimized to obtain maximum recovery of the analytes with the minimum presence of matrix-interfering compounds. The best conditions were obtained at 100 °C with n-hexane using 15 g of silica modified with sulphuric acid (44%, w/w) as sorbent for lipid removal. Quality parameters of the GC-ITMS-MS method were established, achieving good linearity (r > 0.998), between 1 and 500 ng ml⁻¹, and low instrumental limits of detection (0.14-0.76 pg injected). For the whole method, limits of detection ranging from 0.03 to 0.16 ng g⁻¹ wet weight and good precision (RSD < 16%) were obtained.     

Determination of pesticides in seaweeds by pressurized liquid extraction and programmed temperature vaporization-based large volume injection–gas chromatography–tandem mass spectrometry

A rapid method for the simultaneous identification and quantification of pesticide residues in edible seaweed has been developed. Target analytes were three pyrethroid, a carbamate and two organophosphorus pesticides. The procedure consists of a pressurized liquid extraction (PLE) with integrated clean-up, followed by gas chromatography coupled to tandem mass spectrometry. Five PLE parameters were investigated using a screening design: temperature, static extraction time, number of cycles, percent of flush volume and quantitative composition of the n-hexane/ethyl acetate extraction solvent. The effect of the in-cell clean-up with Florisil^® and graphitized carbon black adsorbents was investigated using a Doehlert response surface design. Large volumes of sample extracts were injected using a programmed-temperature vaporizer (PTV-LVI) to improve both sensitivity and selectivity of measurements. Quantification was carried by the internal standard method with surrogate deuterated standards. The method showed excellent linearity (R² > 0.999) and precision (relative standard deviation, RSD ≤ 8%) for all compounds, with detection limits ranging from 0.3 pg g⁻¹ for chlorpyrifos-ethyl, to 3.0 pg g⁻¹ for carbaryl (23.1 pg g⁻¹ for deltamethrin). Recoveries in real seaweed samples were within the range 82–108%. The method was satisfactory validated for the analysis of wild and cultivated edible seaweeds. The presence of pyrethroid and organophosphorus pesticides in some of the samples was evidenced.     

Pressurized solvent extraction followed by gas chromatography tandem mass spectrometry for the determination of benzotriazole light stabilizers in indoor dust

A novel and sensitive method for the determination of five benzotriazole compounds (commonly used as light stabilizers) in indoor dust is presented. Pressurized liquid extraction (PLE) and gas chromatography followed by tandem in time mass spectrometry (GC–MS/MS) were used as sample preparation and determination techniques, respectively. Extraction and clean-up were integrated on-line and, after an evaporative concentration step, the extract provided by the PLE instrument was injected directly in the GC–MS/MS system. Parameters affecting the performance of the sample preparation process were evaluated using experimental factorial designs. Under optimized conditions, analytes were recovered from 0.5 g samples in 3 static extraction cycles of 10 min, using a hexane:dichloromethane (7:3) mixture, at 90 °C. Silica (1 g) was placed in the bottom of the extraction cells as clean-up sorbent. The recoveries of the method varied from 82 to 122%, with standard deviations below 13. The inter-day precision ranged from 9 to 12%, and the limits of quantification (LOQs) remained below 10 ng g⁻¹ for all species. For the first time, four of the five investigated species were found in dust from indoor environments. Their mean concentrations ranged from 71 to 780 ng g⁻¹.     

Determination of tetrabromobisphenol-A,tetrachlorobisphenol-A and bisphenol-A in soil by ultrasonic assisted extraction and gas chromatography–mass spectrometry

In this work, an isotope dilution method for the determination, in agricultural and industrial soil samples, of tetrabromobisphenol-A, tetrachlorobisphenol-A and bisphenol-A by gas chromatography–mass spectrometry was developed. The compounds were extracted from soil by sonication assisted extraction in small columns (SAESC) with a low volume of ethyl acetate as extraction solvent. For dirty soil samples, such as industrial soils, a simultaneous clean-up on an acidified Florisil–anhydrous sodium sulfate mixture was carried out to remove interferences. After extraction, solvent was evaporated and analytes were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and determined by isotope dilution gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC–MS–SIM), using ¹³C₁₂ labeled compounds as internal standards. Recoveries from spiked samples were between 88% and 108% and the estimated limits of detection (S/N = 3) varied from 30 pg g⁻¹ to 90 pg g⁻¹. The response obtained with this method was linear over the range assayed, 5–300 ng ml⁻¹, with correlation coefficients equal or higher than 0.999. The validated method was used to investigate the levels of these phenolic compounds in soil samples collected from different locations in Spain. Bisphenol-A was detected in all samples at concentrations from 0.7 ng g⁻¹ to 4.6 ng g⁻¹ in agricultural soils and from 1.1 ng g⁻¹ to 44.5 ng g⁻¹ in industrial soils. Tetrabromobisphenol-A was found in various soil samples at levels in the range of 3.4–32.2 ng g⁻¹ in industrial soils and at 0.3 ng g⁻¹ in one agricultural soil, whereas tetrachlorobisphenol-A was not detected.     

Gas chromatography–ion trap tandem mass spectrometry method for the analysis of methoxylated polybrominated diphenyl ethers in fish

Gas chromatography coupled to ion trap tandem mass spectrometry (GC–ITMS-MS) is proposed for the analysis of methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in fish and shellfish. MS–MS operating parameters related to the isolation and fragmentation of the precursor ions were optimized to achieve maximum sensitivity and selectivity. This new method allows the determination of both MeO-PBDEs and PBDEs in a single run. Low limits of detection (0.4–2.5 pg injected) and high precision (RSD < 13%) were achieved. A sample treatment based on a selective pressurized liquid extraction (PLE) using Florisil as fat retainer was applied for the analysis of these compounds in fish samples. Method limits of quantification ranged from 0.11 to 0.95 ng g⁻¹ lipid weight for MeO-PBDEs and between 0.18 and 0.50 ng g⁻¹ lipid weight for PBDEs. In addition, good repeatability of the whole method was achieved (RSD < 15%). The suitability of the method was evaluated by analyzing a certified reference material (SRM 1945, whale blubber) with satisfactory results. The developed method was applied to the simultaneous analysis of MeO-PBDEs and PBDEs in fish and shellfish samples from the Mediterranean Sea.     

Pressurised membrane-assisted liquid extraction of UV filters from sludge

A method for the determination of 11 UV-filter compounds in sludge has been developed and evaluated. The procedure includes the use of non-porous polymeric membranes in combination with pressurised liquid extraction (PLE). Firstly, the solid sample, wetted with the extraction solvent, was enclosed into tailor-made bags prepared with low density polyethylene. Secondly, these packages were submitted to a conventional PLE (70 °C, 4 cycles of 5 min static time). Finally, the analytes were determined by liquid chromatography–atmospheric pressure photoionisation–tandem mass spectrometry. The main advantage of this procedure is the reduction of time, solvent and labour effort ought to the combination of extraction and clean-up in a single step. Although the extraction is not quantitative (thus, standard addition is recommended for quantification) selectivity is clearly gained using the membrane as a consequence of the differences of permeation and transport through the membrane between the analytes and other sample matrix components. The optimised protocol provides limits of detection ranging from 0.3 ng g⁻¹ (ethylhexyl dimethyl p-aminobenzoate (OD-PABA)) to 25 ng g⁻¹ (ethylhexyl triazone (EHT)) with only 0.5 g of sludge sample. All the studied UV filters were found in the samples at concentration levels between 1.4 and 2479 ng g⁻¹, emphasising the high adsorption potential of this kind of environmental pollutants onto solid samples such as sludge. Also, this method has permitted the determination of seven of the studied UV filters in sludge samples for the first time.     

Optimized determination of polybrominated diphenyl ethers and polychlorinated biphenyls in sheep serum by solid-phase extraction-gas chromatography-mass spectrometry

We describe a solid-phase extraction (SPE) method, followed by gas chromatography-mass spectrometry (GC-MS), for the simultaneous determination of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in sheep serum samples. The denaturation of serum proteins by formic acid, water-1-propanol and water-2-propanol were compared and optimized. Seven different solid-phase sorbents were tested and it was found that Strata-X cartridge (200 mg, 6 mL) gave the best recoveries (92-106%, SD < 6%, n = 3) for all the target analytes. The different extraction solvents (iso-hexane and dichloromethane), either alone or in combination, were used to extract these persistent organic compounds from spiked serum samples by SPE. Removal of co-extracted biogenic materials was achieved using adsorption chromatography with acid modified silica and activated silica. Iso-hexane was found to be the most appropriate solvent for clean-up providing good recoveries and clear chromatographic separation; its use is preferable to that of DCM because it is less environmentally toxic. The limits of detection (LOD) of the proposed method were 47-105 pg g⁻¹ and 16-24 pg g⁻¹ for the different PBDEs and PCBs studied, respectively. The developed method was linear over the range from 0.05 to 30 ng g⁻¹, for all PBDEs except PBDE 183 (0.10-30 ng g⁻¹), and from 0.02 to 30 ng g⁻¹ for all tested PCB congeners. The established method was successfully applied to sheep serum samples from Scotland, UK, for the determination of the target PBDEs and PCBs.     

Simple approach based on ultrasound-assisted emulsification-microextraction for determination of polibrominated flame retardants in water samples by gas chromatography–mass spectrometry

A simple, efficient, innovative and environmentally friendly analytical technique was successfully applied for the first time for the extraction and preconcentration of polybrominated diphenyl ethers (PBDEs) from water samples. The PBDEs selected for this work were those most commonly found in the literature in natural water samples: 2,2′,4,4′-tetraBDE (BDE-47), 2,2′,4,4,5-pentaBDE (BDE-99), 2,2′,4,4,6-pentaBDE (BDE-100) and 2,2,4,4′,5,5′-hexaBDE (BDE-153). The extracted PBDEs were separated and determined by gas chromatography–mass spectrometry (GC–MS). The extraction/preconcentration technique is based on ultrasound-assisted emulsification-microextraction (USAEME) of a water-immiscible solvent in an aqueous medium. Several variables including, solvent type, extraction time, extraction temperature and matrix modifiers were studied and optimized over the relative response the target analytes. Chloroform was used as extraction solvent in the USAEME technique. Under optimum conditions, the target analytes were quantitatively extracted achieving enrichment factors (EF) higher than 319. The detection limits (LODs) of the analytes for the preconcentration of 10 mL sample volume were within the range 1–2 pg mL⁻¹. The relative standard deviations (RSD) for five replicates at 10 pg mL⁻¹ concentration level were <10.3%. The calibration graphs were linear within the concentration range of 5–5000 pg mL⁻¹ for BDE-47 and BDE-100; and 5–10,000 pg mL⁻¹ for BDE-99 and BDE-153, respectively. The coefficients of estimation were ≥0.9985. Validation of the methodology was performed by standard addition method at two concentration levels (10 and 50 pg mL⁻¹). Recovery values were ≥96%, which showed a successful robustness of the analytical methodology for determination of picogram per milliliter of PBDEs in water samples. Significant quantities of PBDEs were not found in the analyzed samples.     

Development of a simultaneous pressurised-liquid extraction and clean-up procedure for the determination of UV filters in sediments

A useful tool for the determination of eight UV filters in sediments which combines extraction and clean-up in a single-step has been developed. To this end, the protocol incorporates silica gel and copper powder placed directly in the pressurised-liquid extraction (PLE) cell. After extract evaporation, salicylate- and benzophenone-type UV filters are derivatised with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA). Trimethylsilylation increases the sensitivity of these UV filters about 4-10-fold when they are finally analysed by gas chromatography-mass spectrometry (GC-MS). Derivatisation conditions (temperature, time and volume of BSTFA) and PLE parameters (temperature, time, number of cycles and solvent composition) were optimised using multivariate experimental designs. Under optimal conditions, the developed procedure provides an excellent linearity, detection limits (1-5 ng g⁻¹) and recoveries above 73% for all the compounds. Compared to the few existing methods, this analytical approach affords optimal throughput and method automation. Finally, the proposed method was applied to the analysis of three sediment samples.     

An improved method for the simultaneous analysis of phenolic and steroidal estrogens in water and sediment

This paper describes an improved method for the extraction and analysis of seven endocrine disrupting chemicals with wide-ranging polarities from water and sediments using gas chromatography-tandem mass spectrometry (GC-MS/MS). The analytes were 4-tert-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol, 17α-ethynylestradiol and 16α-hydroxyestrone. The optimised GC-MS/MS method produces increased selectivity and sensitivity compared to GC-MS, with limit of detection ranging from 0.01 to 0.49 ng L⁻¹ in water and from 0.05 to 0.14 ng g⁻¹ in sediment. Extraction from aqueous samples was performed by solid-phase extraction (SPE) and from sediment samples by microwave-assisted extraction (MAE). The improved method for the clean-up of sediment extracts carried out by SPE enhanced EDC recovery (86-102%) while reducing matrix interference and sample drying time. Derivatisation of final sample extracts was achieved using N,O-bis(trimethylsilyl)trifluoroacetamide and pyridine, and their stability was enhanced by reconstituting the derivatised extracts with hexane. The method was validated by spiking experiments which showed good recovery and reproducibility. The method was applied to samples taken from the Medway estuary in Kent, UK, where non-conservative behaviour of EDCs was demonstrated.     

Determination of pharmaceuticals in soils and sediments by pressurized liquid extraction and liquid chromatography tandem mass spectrometry

The present work describes the development of a sensitive analytical method based on pressurized liquid extraction (PLE) and pre-concentration by solid-phase extraction (SPE), followed by liquid chromatography–electrospray tandem mass spectrometry (LC–ESI-MS/MS) for the determination of seventeen pharmaceuticals in soils and sediments. The method is based on sample homogenisation using Na₂–EDTA washed sand and extraction with water at 90 °C. Special emphasis was placed on the optimization of the extraction procedure to develop a green method that reduces, at a maximum, the use of organic solvents in order to eliminate matrix components during the clean-up. The proposed method was linear in a concentration range from 0.3 to 333 ng g⁻¹, with correlation coefficients higher than 0.993. Method detection (MDLs) and quantification (MQLs) limits ranged from 0.1 to 6.8 ng g⁻¹ and from 0.25 to 23 ng g⁻¹, respectively. Absolute recoveries were analyte dependent, varying between 50% and 105% at the MQL level, except for fenofibrate (40%) and diclofenac (34%). The intra-day and inter-day precision was given by RSD values from 0.7% to 7.9% and from 1.6% to 14.5%, respectively. Acetaminophen, carbamazepine, ciprofloxacin, clofibric acid, codeine, diazepam, fenofibrate, metropolol, ofloxacin and propanolol were detected at concentrations from MDL to 35.62 ng g⁻¹ in soils and sediments from marsh areas. Due to the low recoveries, results for fenofibrate and diclofenac can only be considered as semi-quantitative. The method was fully suitable for the other 15 pharmaceuticals.     

On-line coupling of dynamic microwave-assisted extraction to solid-phase extraction for the determination of sulfonamide antibiotics in soil

A rapid technique based on dynamic microwave-assisted extraction (DMAE) coupled on-line with solid-phase extraction (SPE) was developed for the determination of sulfonamides (SAs) including sulfadiazine, sulfameter, sulfamonomethoxine and sulfaquinoxaline in soil. The SAs were first extracted with acetonitrile under the action of microwave energy, and then directly introduced into the SPE column which was packed with neutral alumina for preconcentration of analytes and clean-up of sample matrix. Subsequently, the SAs trapped on the alumina were eluted with 0.3% acetic acid aqueous solution and determined by liquid chromatography-tandem mass spectrometry. The DMAE parameters were optimized by the Box-Behnken design. Maximum extraction efficiency was achieved using 320 W of microwave power; 12 mL of extraction solvent and 0.8 mL min⁻¹ of extraction solvent flow rate. The limits of detection and quantification obtained are in the range of 1.4-4.8 ng g⁻¹ and 4.6-16.0 ng g⁻¹ for the SAs, respectively. The mean values of relative standard deviation of intra- and inter-day ranging from 2.7% to 5.3% and from 5.6% to 6.7% are obtained, respectively. The recoveries of SAs obtained by analyzing four spiked soil samples at three fortified levels (20 ng g⁻¹, 100 ng g⁻¹ and 500 ng g⁻¹) were from 82.6 ± 6.0% to 93.7 ± 5.5%. The effect of standing time of spiked soil sample on the SAs recoveries was examined. The recoveries of SAs decreased from (86.3-101.9)% to (37.6-47.5)% when the standing time changed from one day to four weeks.     

Method for determination of fatty acid amides in polyethylene packaging materials—Gas chromatography/mass spectrometry

A new method for determination of fatty acid amides in polyethylene packaging film was developed using gas chromatography/mass spectrometry (GC/MS). Liquid extraction, Soxhlet extraction ultrasonic-assisted extraction and pressurized solvent extraction (PSE) methods were compared and the results showed that pressurized solvent extraction was the best for extracting these compounds. After extraction, solvent was blown by nitrogen and a trifluoroethyl derivation step was carried out. The derivative compounds were identified and quantified by GC/MS using an HP-Innowax column. The retention times were 6.20 min for derivative hexadecanoamide, 8.56 min for derivative octadecanamide, 8.84 min for derivative oleamide and 13.68 min for derivative erucamide, respectively. The detection limits were 61.0 ng g⁻¹, 74.0 ng g⁻¹, 103.0 ng g⁻¹, and 105.0 ng g⁻¹, respectively, and the linearity were good. The proposed method was applied satisfactorily to determine these chemicals in different types of polyethylene samples.     

Determination of polybrominated diphenyl ethers in fish tissues by matrix solid-phase dispersion and gas chromatography coupled to triple quadrupole mass spectrometry: Case study on European eel (Anguilla anguilla) from Mediterranean coastal lagoons

This paper describes the development and validation of an analytical methodology to determine 28 polybrominated diphenyl ethers (PBDEs) in European eel (Anguilla anguilla) tissues using matrix solid-phase dispersion (MSPD) and gas chromatography coupled to triple quadrupole mass spectrometry (GC-QQQ-MS/MS). A total of 28 PBDEs were targeted, including tri- to deca-brominated congeners.The robustness and effectiveness of the proposed sample preparation procedure was demonstrated in lipid-rich eel tissues. The use of batch MSPD with activated silica gel and H₂SO₄-impregnated silica gel, followed by H₂SO₄ digestion and multilayer cartridge clean-up allowed for complete lipid removal and eliminated matrix effects during GC-QQQ-MS/MS analysis. The average PBDE recoveries from eel muscle samples spiked with PBDEs at two levels were in the range 56.2-119.0%. Precision was satisfactory since relative standard deviations were lower than 19.6%, regardless of spike level, and method quantification limits ranged between 1 and 170 pg g⁻¹ (wet weight).The method demonstrated its successful application for the analysis of eel samples from two coastal lagoons located on the western French Mediterranean coast. All samples tested positive, but for tri- to hexa-brominated congeners only and total PBDE levels observed in this study were in the range 0.08-1.80 ng g⁻¹ wet weight.     

Development of a method for the analysis of seven banned azo-dyes in chilli and hot chilli food samples by pressurised liquid extraction and liquid chromatography with electrospray ionization-tandem mass spectrometry

An automated, confirmatory and sensitive procedure has been developed and validated for the determination of Sudan (I-IV), Sudan Orange G, Sudan Red 7B and Para Red in hot chilli food samples. The proposed method includes pressurised liquid extraction (PLE) with acetone, gel permeation chromatography (GPC) clean-up and detection by liquid chromatography (LC) coupled to electrospray ionization in positive mode tandem mass spectrometry (ESI-MS-MS). The main parameters affecting the performance of the different ionization sources and PLE parameters were previously optimised using statistical design of experiments (DOE). The method was in-house validated on chilli powder and chilli meat. Linear calibrations were obtained with correlation coefficients R² > 0.999. The limits of detection (LOD) and quantification (LOQ) of the method were in the ranges of 0.002-0.012 ng g⁻¹ and 0.006-0.036 ng g⁻¹, respectively for chilli powder. The decision limit and detection capability were between 0.005-0.022 ng g⁻¹ and 0.007-0.026 ng g⁻¹, respectively for chilli meat. Recoveries ranged from 94% to 105%. The applicability of the method to the determination of azo-dyes in hot chilli products was demonstrated.     

Determination of polybrominated diphenyl ethers in water and soil samples by cloud point extraction-ultrasound-assisted back-extraction-gas chromatography–mass spectrometry

A novel and efficient analytical methodology is proposed for extracting and preconcentrating polybrominated diphenyl ethers (PBDEs) from samples of environmental interest prior gas chromatography–mass spectrometry (GC–MS) analysis. It is based on the induction of micellar organized medium by using a non-ionic surfactant (Triton X-114) to extract the target PBDEs. To enable coupling the efficient extracting technique with GC analysis, ultrasound-assisted back-extraction (UABE) into an organic solvent was required. Several factors, including surfactant type and concentration, equilibration temperature and time, ionic strength, pH and buffers nature and concentration were studied and optimized over the extraction efficiency of the proposed technique. Under optimal experimental conditions, the target analytes were quantitatively extracted achieving an enrichment factor of 250 when 10 mL aliquot of ultrapure water spiked with PBDE-standard mixture (10 pg mL⁻¹ each PBDE) was extracted. Method detection limits (MDLs) calculated with aqueous PBDEs solutions as three times the signal-to-noise ratio (S/N), ranged from 1 to 2 pg mL⁻¹ with RSDs values ≤8.5% (n = 5). The coefficients of estimation of the calibration curves obtained following the proposed methodology were ≥0.9987 and linear range of all PBDEs was 4–150 pg mL⁻¹. The proposed methodology was validated by carrying out a recovery study by spiking the samples at two different concentration levels of PBDEs (10 and 50 pg mL⁻¹ for waters samples). Recoveries values in the range of 96–106% for water samples were obtained showing satisfactory robustness of the method for analyzing PBDEs in water samples. The proposed methodology was applied for the analysis of PBDEs: 2,2′,4,4′-tetraBDE (BDE-47), 2,2′,4,4,5-pentaBDE (BDE-99), 2,2′,4,4,6-pentaBDE (BDE-100) and 2,2,4,4′,5,5′-hexaBDE (BDE-153) in water samples, including drinking, lake, river water and soil samples. Significant quantities of PBDEs were not found in the analyzed samples.     

Rapid and sensitive gas chromatography–ion-trap tandem mass spectrometry method for the determination of tobacco-specific N-nitrosamines in secondhand smoke

Tobacco-specific nitrosamines (TSNAs) are some of the most potent carcinogens in tobacco and cigarette smoke. Accurate quantification of these chemicals is needed to help assess public health risks. We developed and validated a specific and sensitive method to measure four TSNAs adsorbed to model surfaces and secondhand smoke (SHS) particles using gas chromatography–ion-trap tandem mass spectrometry. In an 18-m³ room-sized chamber, a smoking machine generated realistic concentrations of SHS that were actively sampled on Teflon-coated fiber glass (TCFG) filters, and passively sampled on cellulose substrates. A simple solid–liquid extraction protocol using methanol as solvent was successfully applied to both substrates with recoveries ranging from 85 to 115%. For each TSNA, tandem MS parameters were optimized and the major fragmentation pathways were elucidated. The method showed excellent performance, with a linear dynamic range from 2 to 1000 ng mL⁻¹, low detection limits (S/N > 3) of 30–300 pg mL⁻¹ and precision with experimental errors below 10% for all compounds. Moreover, no interfering peaks were observed, indicating a high selectivity of MS/MS without the need for a sample clean-up step. This method provides a suitable analytical tool to detect and quantify traces of TSNA in indoor environments polluted with SHS.     

Development of an analytical methodology for the determination of the antiparasitic drug toltrazuril and its two metabolites in surface water,soil and animal manure

This paper presents the development, optimization and validation of a LC–MS/MS methodology to determine the antiparasitic veterinary drug toltrazuril and its two main metabolites, toltrazuril sulfoxide and toltrazuril sulfone, in environmental surface water, soil and animal manure. Using solid phase extraction and selective pressurized liquid extraction with integrated clean-up, the analytical method allows for the determination of these compounds down to 0.06–0.13 ng L⁻¹ in water, 0.01–0.03 ng g⁻¹ dw in soil and 0.22–0.51 ng g⁻¹ dw in manure. The deuterated analog of toltrazuril was used as internal standard, and ensured method accuracy in the range 96–123% for water and 77–110% for soil samples. The developed method can also be applied to simultaneously determine steroid hormones in the solid samples. The antiparasitic drug and its metabolites were found in manure and soil up to 114 and 335 pg g⁻¹ dw, respectively. Little is known regarding the environmental fate and effects of these compounds; consequently more research is urgently needed.     

Preparation of magnetic strong cation exchange resin for the extraction of melamine from egg samples followed by liquid chromatography-tandem mass spectrometry

In the work, magnetic strong cation exchange (MSCX) resins were prepared using hydrophobic Fe₃O₄ magnetite as the magnetically susceptible component, styrene and divinylbenzene as polymeric matrix components, acetyl sulfonate as the sulfonation agent. The resins were successfully applied to the extraction of melamine (MEL) from egg samples. The extraction procedure was carried out in a single step by blending and stirring the sample, extraction solvent and the magnetic resins. The MEL was extracted from the sample matrix then adsorbed onto the resins directly through ion-exchange interaction. When the extraction was completed, the resins with adsorbed analyte were easily separated from the sample matrix by applying an appropriate magnetic field. Main factors affecting the extraction of MEL such as the amount of MSCX resins, extraction time, washing and eluting conditions were optimized. The MEL eluted from the resins was determined by liquid chromatography-tandem mass spectrometry. The linearity of quantification obtained by analyzing matrix-matched standards is in the range of 10-1000 ng g⁻¹. The limit of detection and quantification obtained are 2.6 and 8.8 ng g⁻¹, respectively. The relative standard deviations of intra- and inter-day ranging from 1.6% to 6.5% and from 2.1% to 7.2% are obtained. The recoveries of MEL are in the range of 77.2-99.3%. The proposed method was successfully applied to determine MEL in eggs obtained from different local markets. MEL was detectable with the contents of 43.5 and 234.1 ng g⁻¹ in two samples.