Matrix solid-phase dispersion extraction of organophosphorous pesticides from beeswax

Beeswax is a complex mixture of lipophilic compounds and other components such as aliphatic alcohols and carotenoids. Then, extraction and clean-up for pesticide analysis in beeswax is a challenge. In this work, a multiresidue method for the analysis of dichlorvos (DCV), diazinon, malathion, methyl parathion and coumaphos (CMF) in beeswax was developed. The proposed approach is based on matrix solid-phase dispersion extraction. The adsorbent for sample clean-up was studied and a simplex-centroid cubic statistical design was applied to evaluate pure solvents and their binary and ternary mixtures to elute the analytes. Finally, Florisil and ethyl acetate were chosen as solid support and eluting solvent, respectively. After extraction, pesticides were separated and detected by gas chromatography/mass spectrometry. The method achieved acceptable recoveries (70–85%; except for DCV, 24–38%) with relative standard deviations below 5%. The repeatability of the method was lower than 8% and interday variability was below 12%. The limit of detection (LOD) for the analytes varies between 0.2 and 2.6 µg?kg^?1 and limit of quantification from 0.93 to 8.8 µg?kg^?1. LOD reached for CMF was below the maximum residue limit allowed by the legislation of the United States and Canada.     

Determination of organochlorine pesticides in propolis by gas chromatography-electron capture detection using double column series solid-phase extraction

A rapid and reliable method was developed and applied for the simultaneous determination of 17 organochlorine pesticides (OCPs) in propolis. After extraction with hexane and acetone (1:1, v/v), four sorbents (florisil, silica, graphitized carbon, and tandem graphitized carbon plus florisil) were assayed for the clean-up step. The elution solvents hexane and ethyl acetate (1:1, v/v), hexane and dichloromethane (3:7, v/v), and ethyl acetate and hexane (2:8, v/v) were studied. The results showed that the combination of the tandem graphitized carbon and florisil cartridge with the elution solvent of 6mL of ethyl acetate and hexane (2:8, v/v), which was capable of eliminating matrix interference and providing colorless eluates, was the most efficient clean-up procedure for propolis extracts when testing for OCPs. The analytical technique employed was gas chromatography with electron capture detection (GC–ECD). The correlation coefficients from linear regression for the analyzed concentrations (5∼100 μg/kg) were >0.9961. The limits of detection (LODs) varied between 0.8 μg/kg for 4,4′-DDE and 11.4 μg/kg for endosulfan II, and the limits of quantitation (LOQs) ranged from 2.6 to 38.1 μg/kg. The average recoveries varied between 62.6 and 109.6%. Relative standard deviations (RSD%) ranged from 0.8 to 9.4%. Sample analysis indicated that 4,4′-DDE was detected more often in propolis than other pesticides, such as β-HCH, δ-HCH and heptachlor. Figure GC-ECD chromatogram of a standard solution with 0.1 mg/L of OCPs     

固相萃取–气相色谱法测定饮用水中5种有机磷农药

建立了固相萃取–气相色谱法测定饮用水中敌敌畏、乐果、甲基对硫磷、马拉硫磷及对硫磷的方法。采用Cleanert PEP–SPE固相萃取柱,以二氯甲烷、乙酸乙酯、甲醇及纯水活化固相萃取柱,以5 m L/min流量富集水样,然后用二氯甲烷及乙酸乙酯洗脱浓缩后进行气相色谱分析。5种有机磷农药线性相关系数均大于0.995,方法测定下限为0.16~0.80μg/L,加标回收率为59.8%~109.0%,测定结果的相对标准偏差小于16%(n=6)。该方法灵敏度高,准确度好,适用于饮用水中5种有机磷农药的检测。     

Response surface optimization for determination of pesticide residues in grapes using MSPD and GC-MS: assessment of global uncertainty

In this work, a simple and low-cost method based on matrix solid-phase dispersion (MSPD) and gas chromatography to determine eight multi-class pesticides such as vinclozolin, dichlofluanid, penconazol, captan, quinoxyfen, fluquinconazol, boscalid, and pyraclostrobin in grapes is described. Fungicide residues were identified and quantified using gas chromatography–mass spectrometry in selected ion monitoring mode (GC-MS, SIM). The experimental variables that affect the MSPD method, such as the amount of solid phase, solvent nature and elution volume were optimized using an experimental design. The best results were obtained using 0.5 g of grapes, 1.0 g of silica as clean-up sorbent, 1.50 g of C₁₈ as bonded phase and 10 mL of dichloromethane/ethyl acetate (1:1, v/v) as eluting solvent. Significant matrix effects observed for most of the pesticides tested were eliminated using matrix-matched standards. The pesticide recoveries in grapes samples were better than 80% except for captan. Intra-laboratory precision in terms of Horwitz ratio of the pesticides evaluated was below 0.5, suggesting ruggedness of the method. The quantification limits of the pesticides were in the range of 3.4–8.7 μg kg⁻¹, which were lower than the maximum residue limits (MRLs) of the pesticides in grapes samples established by the European legislation. Decision limits (CCα) and detection capability (CCβ) have been calculated. The expanded uncertainties at two levels of concentration were <20% for all analytes.     

MSPD procedure for determining buprofezin,tetradifon, vinclozolin,and bifenthrin residues in propolis by gas chromatography–mass spectrometry

A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine bifenthrin, buprofezin, tetradifon, and vinclozolin in propolis using gas chromatography–mass spectrometry in selected ion monitoring mode (GC–MS, SIM). Different method conditions were evaluated, for example type of solid phase (C₁₈, alumina, silica, and Florisil), the amount of solid phase and eluent (n-hexane, dichloromethane, dichloromethane–n-hexane (8:2 and 1:1, v/v) and dichloromethane–ethyl acetate (9:1, 8:2 and 7:3, v/v)). The best results were obtained using 0.5 g propolis, 1.0 g silica as dispersant sorbent, 1.0 g Florisil as clean-up sorbent, and dichloromethane–ethyl acetate (9:1, v/v) as eluting solvent. The method was validated by analysis of propolis samples fortified at different concentration levels (0.25 to 1.0 mg kg⁻¹). Average recoveries (four replicates) ranged from 67% to 175% with relative standard deviation between 5.6% and 12.1%. Detection and quantification limits ranged from 0.05 to 0.10 mg kg⁻¹ and 0.15 to 0.25 mg kg⁻¹ propolis, respectively.     

固相萃取–毛细管气相色谱法同时测定水体中8种有机磷类农药残留

建立固相萃取–毛细管气相色谱法同时测定水体中敌敌畏、乙酰甲胺磷、治螟磷、乐果、甲基对硫磷、马拉硫磷、杀螟硫磷和水胺硫磷8种有机磷类农药残留。样品经OASIS HLB固相萃取柱富集,丙酮洗脱,用毛细管气相色谱(FPD)法进行定量分析。8种有机磷类农残留的质量浓度在0.05~4.0μg/m L范围内与色谱峰面积线性关系良好,相关系数均大于0.998,方法检出限为0.004~0.01μg/m L。测定结果的相对偏差为2.6%~4.5%(n=6),加标回收率为81.6%~106.2%。该方法操作简单、灵敏度高,可用于检测水体中的8种有机磷类农药残留。     

Optimization of matrix solid-phase dispersion conditions for UV filters determination in biota samples

A low solvent consumption method for the determination of eight ultraviolet (UV) filters, displaying low to medium polarities, in freeze-dried samples of marine bivalves and fish is proposed. Matrix solid-phase dispersion (MSPD) and gas chromatography with mass spectrometry (GC-MS) were used as sample preparation and determination techniques, respectively. This work describes the influence of several parameters (type and amount of dispersant and clean-up sorbents, as well as elution solvent) on the yield and the selectivity of the MSPD extraction. Under optimized conditions, samples (0.5?g) were ground with 2?g of Florisil in a mortar with a pestle and transferred into a polypropylene syringe, which contained 1?g of C18 as clean-up sorbent. Analytes were eluted with 5?mL of acetonitrile. This extract was concentrated to dryness, re-constituted with 1?mL of ethyl acetate and injected in the GC-MS system without any further clean-up. The global average recoveries, measured for three different biota samples, spiked at three different levels (between 50 and 1000?ng?g^?1), ranged from 80% to 101% with associated standard deviations below 10%. The inter-day precision of the method varied from 4% to 15% and the achieved LOQs (defined for a signal to noise ratio of 10) ranged from 4 to 28?ng?g^?1, referred to the freeze-dried matrix. Octocrylene (OCR) was found in some samples of fish and mussels at concentrations between 15 and 20?ng?g^?1, referred to dry mass.     

Simultaneous determination of eight pesticide residues in coconut using MSPD and GC/MS

A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine dimethoate, malathion, lufenuron, carbofuran, 3-hydroxycarbofuran, thiabendazole, difenoconazole and trichlorfon in coconut pulp using gas chromatography-mass spectrometry with selected ion monitoring (GC/MS, SIM). Different parameters of the method were evaluated, such as type of solid-phase (C(18), alumina, silica-gel and Florisil), the amount of solid-phase and eluent (dichloromethane, acetone, ethyl acetate, acetonitrile, n-hexane and n-hexane:ethyl acetate (1:1, v/v)). The best results were obtained using 0.5 g of coconut pulp, 1.0 g of C(18) as dispersant sorbent, 1.0 g of Florisil as clean-up sorbent and acetonitrile saturated with n-hexane as eluting solvent. The method was validated using coconut pulp samples fortified with pesticides at different concentration levels (0.25-1.0 mg kg(-1)). Average recoveries (four replicates) ranged from 70.1% to 98.7%, with relative standard deviations between 2.7% and 14.7%, except for lufenuron and difenoconazole, for which recoveries were 47.2% and 48.2%, respectively. Detection and quantification limits for coconut pulp ranged from 0.02 to 0.17 mg kg(-1) and from 0.15 to 0.25 mg kg(-1), respectively.     

Determination of coumaphos, chlorpyrifos and ethion residues in propolis tinctures by matrix solid-phase dispersion and gas chromatography coupled to flame photometric and mass spectrometric detection

A new analytical method has been developed and successfully evaluated in routine application for the quantitative analysis of a selected group of organophosphate pesticides (coumaphos, chlorpyrifos and ethion) which can be found at trace levels in propolis tinctures (ethanolic propolis extracts); a valuable commodity used as raw material in the food and pharmaceutical industries for which there have been few attempts for pesticide residue analysis reported in the literature. The proposed methodology is based on matrix solid phase dispersion (MSPD) using aluminum sulfate anh. a novel dispersant material and subsequent column chromatography clean-up in silica gel prior to gas chromatography (GC) with both flame photometric detector (FPD) and mass spectrometry (MS) detection used for the routine quantification and identification of the residues, respectively. The limits of detection, for coumaphos, chlorpyrifos and ethion were below 26.0 μg/kg in FPD and 1.43 μg/kg for MS detection. Mean recoveries were in the range of 85-123% with RSD values below 13%, which suggests that the proposed method is fit for the purpose of analyzing pesticides in propolis tinctures containing high concentration of polyphenolics. The method has been successfully applied in our laboratory for the last 2 year in the analysis of real propolis tinctures samples.     

Determination of organophosphorus insecticides in natural waters using SPE-disks and SPME followed by GC/FTD and GC/MS

Two methods for the analysis of ten organophosphorus insecticides in natural waters using solid phase extraction disks containing C₁₈ and SDB and solid phase microextraction fibers containing polyacrylate (PA) are developed. Bromophos ethyl, bromophos methyl, dichlofenthion, ethion, fenamiphos, fenitrothion, fenthion, malathion, parathion ethyl and parathion methyl were determined by GC/MS and GC/FTD. The SPE-disks require only 1000 mL of sample and provide a method limit of detection in the range of 0.01–0.07 μg/L and recovery rates from 60.7 to 104.1%. The solid phase microextraction (SPME) technique requires 2–5 mL of water sample and provides a method limit of detection in the range of 0.01 to 0.05 μg/L for all detectors and the recoveries compared to distilled water ranged from 86.2 to 119.7%. The proposed methods were applied to the trace level screening determination of insecticides in river water samples originating from different Greek regions.     

Determination of organophosphorus insecticides in natural waters using SPE-disks and SPME followed by GC/FTD and GC/MS

Two methods for the analysis of ten organophosphorus insecticides in natural waters using solid phase extraction disks containing C18 and SDB and solid phase microextraction fibers containing polyacrylate (PA) are developed. Bromophos ethyl, bromophos methyl, dichlofenthion, ethion, fenamiphos, fenitrothion, fenthion, malathion, parathion ethyl and parathion methyl were determined by GC/MS and GC/FTD. The SPE-disks require only 1000 mL of sample and provide a method limit of detection in the range of 0.01-0.07 microgram/L and recovery rates from 60.7 to 104.1%. The solid phase microextraction (SPME) technique requires 2-5 mL of water sample and provides a method limit of detection in the range of 0.01 to 0.05 microgram/L for all detectors and the recoveries compared to distilled water ranged from 86.2 to 119.7%. The proposed methods were applied to the trace level screening determination of insecticides in river water samples originating from different Greek regions.     

Microwave-assisted extraction and large-volume injection gas chromatography tandem mass spectrometry determination of multiresidue pesticides in edible seaweed

A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection gas chromatography–tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g⁻¹ and the limits of quantification were between 2.3 and 76.9 pg g⁻¹, far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed samples.     

水果蔬菜中多种杀菌剂的基质固相分散液相色谱测定方法研究

采用基质固相分散(MSPD)代替液液分配和固相萃取,从蔬菜水果中提取、净化10种常用杀菌剂农药残留,用C18硅胶交联剂作为固相吸附剂,乙酸乙酯作为洗脱液,用HPLC/PDA和LC-MS进行分析检测。10种杀菌剂在0.5~5 mg/kg含量的添加回收率在65%~110%之间,相对标准偏差小于10%,使用HPLC、PDA和LC-MS的检出限分别在0.02~0.2 mg/kg和0.002~0.01 mg/kg之间。该方法节省溶剂,提取和净化一步完成,适用于新鲜水果和蔬菜中10种杀菌剂的残留分析。     

Matrix solid-phase dispersion extraction of carbadox and olaquindox in feed followed by hydrophilic interaction ultra-high-pressure liquid chromatographic analysis

A new method involving matrix solid-phase dispersion (MSPD) extraction and hydrophilic interaction ultra-high-pressure liquid chromatography (HILIC-UHPLC) with photodiode array detection was developed for the determination of carbadox and olaquindox in feed. Separation of carbadox and olaquindox was achieved within 1 min on the 1.7 microm Acquity UPLC BEH HILIC column by using isocratic elution with a mobile phase consisting of 10 mmol L(-1) ammonium acetate in acetonitrile-water (95:5, v/v) at a flow rate of 0.5 mL min(-1). Optimization of MSPD extraction parameters, such as type of solid sorbent and elution solvent were carried out. Optimal conditions selected for MSPD extraction were: 0.25 g of feed sample, 0.5 g of octadecylsilica as solid sorbent and 10 mL of acetonitrile-methanol (8:2, v/v) as eluting solvent. Both analytes provided average recoveries from spiked feed samples ranging from 89.1 to 98.4% with relative standard deviations less than 10%. Obtained performance characteristics are comparable to those achieved by liquid-liquid extraction-HPLC with the advantages of being simpler and significantly faster.     

Application of multiwall carbon nanotubes-based matrix solid phase dispersion extraction for determination of hormones in butter by gas chromatography mass spectrometry

The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase dispersion (MSPD) was applied for the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, medroxyprogesterone, progesterone and norethisterone acetate in butter samples. The method includes MSPD extraction of the target analytes from butter samples, derivatization of hormones with heptafluorobutyric acid anhydride-acetonitrile mixture, and determination by gas chromatography-mass spectrometry. The mixture containing 0.30 g graphitized MWCNTs and 0.10 g MWCNTs was selected as absorbent. Ethyl acetate was used as elution solvent. The elution solvent volume and flow rate were 12 mL and 0.9 mL min(-1), respectively. The recoveries of hormones obtained by analyzing the five spiked butter samples were from 84.5 to 111.2% and relative standard deviations from 1.9 to 8.9%. Limits of detection and quantification for determining the analytes were in the range of 0.2-1.3 and 0.8-4.5 μg kg(-1), respectively. Compared with other traditional methods, the proposed method is simpler in the operation and shorter in the sample pretreatment time.     

Determination of parabens and endocrine-disrupting alkylphenols in soil by gas chromatography–mass spectrometry following matrix solid-phase dispersion or in-column microwave-assisted extraction: a comparative study

Two rapid methods were evaluated for the simultaneous extraction of seven parabens and two alkylphenols from soil based on matrix solid-phase dispersion (MSPD) and microwave-assisted extraction (MAE). Soil extracts were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide and analyzed by gas chromatography with mass spectrometry. Extraction and clean-up of samples were carried out by both methods in a single step. A glass sample holder, inside the microwave cell, was used in MAE to allow the simultaneous extraction and clean-up of samples and shorten the MAE procedure. The detection limits achieved by MSPD were lower than those obtained by MAE because the presence of matrix interferences increased with this extraction method. The extraction yields obtained by MSPD and MAE for three different types of soils were compared. Both procedures showed good recoveries and sensitivity for the determination of parabens and alkylphenols in two of the soils assayed, however, only MSPD yielded good recoveries with the other soil. Finally, MSPD was applied to the analysis of soils collected in different sites of Spain. In most of the samples analyzed, methylparaben and butylparaben were detected at levels ranging from 1.21 to 8.04 ng g⁻¹ dry weight and 0.48 to 1.02 ng g⁻¹ dry weight, respectively.     

Matrix solid phase dispersion–Soxhlet simultaneous extraction clean-up for determination of organochlorine pesticide residues in tobacco

A novel method combining matrix solid phase dispersion (MSPD) with Soxhlet simultaneous extraction clean-up (SSEC) was developed. Being a single-step extraction and clean-up procedure, it could be used instead of multistep solvent extraction and Florisol column clean-up. It not only reduces sample contamination during the procedure, but it also decreases the amount of organic solvent needed. The retention times of standards were used to qualitatively assess the method, and the external standard method was used to quantitatively assess it. Residues of organochlorine pesticides (OCP) in tobaccos were determined by gas chromatography–electron capture detection (GC–ECD), and their identities were confirmed by the standard addition method (SAM). The performance of the method was evaluated and validated: the detection limit was 0.01–0.02 μg g⁻¹, relative standard deviations were 5–26%, and recoveries were 72–99% at fortification levels of 0.10, 1.00 and 10.0 μg g⁻¹. The analytical characteristics of MSPD–SSEC compared very favorably with the results from the classical multistep solvent extraction and Florisol column clean-up method.     

Determination of insecticides in honey by matrix solid-phase dispersion and gas chromatography with nitrogen-phosphorus detection and mass spectrometric confirmation

A multiresidue method was developed for the determination of 12 organophosphorus insecticides (diazinon, parathion methyl, fenitrothion, pirimiphosmethyl, malathion, fenthion, chlorpyrifos, quinalphos, methidathion, ethion, azinphosmethyl, coumaphos), one carbamate (pirimicarb), and one amidine (amitraz) in unifloral and multifloral honeys. The analytical procedure was based on the matrix solid-phase dispersion of honey on a mixture of Florisil and anhydrous sodium sulfate in small glass columns and subsequent extraction with a low volume of hexane-ethyl acetate (90 + 10, v/v), assisted by sonication. The insecticide residues were determined by capillary chromatography with nitrogen-phosphorus detection and confirmed by mass spectrometry. Average recoveries at the 0.05-0.5 microg/g levels were >80% for organophosphorus insecticides and about 60% for the other insecticides, pirimicarb and amitraz, with relative standard deviations <10%. The detection limit for the different insecticides ranged between 6 and 15 microg/kg. The main advantages of the proposed method are that extraction and cleanup are performed in a single step with a low volume of organic solvent. The method is simple, rapid, and less laborious than conventional methods. Several Spanish honeys were analyzed with the proposed method and no residues of the studied insecticides were found.     

Determination of phenolic compounds in wines by novel matrix solid-phase dispersion extraction and gas chromatography/mass spectrometry

A novel matrix solid-phase dispersion (MSPD) extraction method was developed to extract simultaneously 23 phenolic compounds from wine samples prior to determination by gas chromatography with mass spectrometric detection in the selected ion monitoring mode. Different parameters of the MSPD technique such as dispersant solid-phase, eluting solvent, and sample ionic strength and pH were optimized. The optimized MSPD procedure requires a small volume of wine (1 mL), commercial silica gel (1.5 g) as dispersant solid-phase and a small volume of ethyl acetate (5 mL) as eluting solvent. Under these conditions, the extraction of the studied compounds was almost complete (mean values of recoveries between 87 and 109%) in a short time (15 min). Moreover, satisfactory standard deviations of repeatability (RSD<9% in most cases), linear regression coefficients (r(2)>0.993) and detection limits (<8 microg/L) confirm the usefulness of the methodology for routine monitoring of the concentration of individual phenolic antioxidants in wines. Application was illustrated by analysis of different wine samples.     

Ultra-preconcentration and determination of thirteen organophosphorus pesticides in water samples using solid-phase extraction followed by dispersive liquid–liquid microextraction and gas chromatography with flame photometric detection

An ultra-preconcentration technique composed of solid-phase extraction (SPE) and dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–flame photometric detection (GC–FPD) was used for determination of thirteen organophosphorus pesticides (OPPs) including phorate, diazinon, disolfotane, methyl parathion, sumithion, chlorpyrifos, malathion, fenthion, profenphose, ethion, phosalone, azinphose-methyl and co-ral in aqueous samples. The analytes were collected from large volumes of aqueous solutions (100 mL) into 100 mg of a SPE C₁₈ sorbent. The effective variables of SPE including type and volume of elution solvent, volume and flow rate of sample solution, and salt concentration were investigated and optimized. Acetone was selected as eluent in SPE and disperser solvent in DLLME and chlorobenzene was used as extraction solvent. Under the optimal conditions, the enrichment factors were between 15,160 and 21,000 and extraction recoveries were 75.8–105.0%. The linear range was 1–10,000 ng L^?1 and limits of detection (LODs) were between 0.2 and 1.5 ng L^?1. The relative standard deviations (RSDs) for 50 ng L^?1 of OPPs in water with and without an internal standard, were in the range of 1.4–7.9% (n = 5) and 4.0–11.6%, respectively. The relative recoveries of OPPs from well and farm water sat spiking levels of 25 and 250 ng L^?1 were 88–109%.