Optimization of matrix solid-phase dispersion extraction method for the analysis of isoflavones in Trifolium pratense

A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 12 isoflavones in Trifolium pratense L. Dried leaf samples were blended with C₁₈, placed in small columns and isoflavones extracted with dichloromethane–methanol. Analyses were performed by high performance liquid chromatography with diode array detection (HPLC-DAD) with 2-methoxyflavone as internal standard. Several dispersants, eluents and clean-up steps were tested during the optimization of the process in order to obtain the best selectivity and yields. Mean recoveries ranged from 70% to 119%, with relative standard deviations <18%. The limits of detection were between 0.006 mg/l for biochanin A and 0.108 mg/l for daidzin. The performance of the optimized method in real samples was compared with a conventional method based in solid–liquid extraction (SLE).     

固相萃取法与基质固相分散法在橙子中有机磷农药残留分析中的应用

建立了固相萃取(SPE)-反相高效液相色谱(RP-HPLC)同时测定橙子中痕量辛硫磷、二嗪农有机磷农药残留量的方法。样品经甲醇超声提取、C18固相萃取柱净化后,采用液相色谱柱分离,以乙腈-水(体积比为85∶15)为流动相等度洗脱,于254 nm下紫外检测。结果表明:在0.1～10.0 mg/L和0.4～10.0 mg/L范围内,辛硫磷、二嗪农的质量浓度与峰面积呈良好的线性关系;样品的加标平均回收率为87.3%～102.7%,相对标准偏差(RSD)为0.9%～4.9%。将该分析结果与用基质固相分散法(MSPD)处理样品所得的结果相比较,发现SPE对二嗪农的提取效果较好,而MSPD对辛硫磷的提取效果较好,但两种方法都能较好地净化样品,均能满足残留量的分析要求。     

Analysis of pesticide residues in fruit and vegetables by matrix solid phase dispersion (MSPD) and different gas chromatography element-selective detectors

Summary A comparison between different element selective detectors for the determination of organophosphorus and organochlorine pesticide residues, from fruit and vegetables, was performed by capillary GC with electron capture detector (ECD), nitrogen phosphorus detector (NPD), flame photometric detector (FPD) in the sulphur and phosphorus modes, and mass spectrometry detector (MSD) in selected ion monitoring (SIM) mode. Pesticides were extracted from the different foodstuffs by Matrix Solid Phase Dispersion (MSPD). Recoveries of 41–108 % with relative standard deviation of 2–14 % in the concentration range 0.5–10 μg L⁻¹ were obtained in oranges, lemons, grapefruit, pears, plums, lettuces and tomatoes. The results demonstrated that the extracts of all the samples can be analyzed by the detectors used since no interfering co-extracted compounds were detected.     

Screening of fluoroquinolones in environmental waters using disk-based solid-phase extraction combined to microplate fluorimetric determination and LC-MS/MS

Fluoroquinolones are in the order of the day concerning environmental contamination through anthropogenic activities, resulting in increased risk for antibiotic resistance dissemination. In this context, accessible, low-cost analytical methods are required for implementation of comprehensive surveillance and screening schemes. In this work, we propose a down-scaled disk-based solid-phase extraction system from which the eluate can be first screened by miniaturized fluorimetric reading, followed by individual determination of target fluoroquinolones (ciprofloxacin, norfloxacin, and enrofloxacin) by liquid chromatography combined to tandem mass spectrometry. The fluorimetric measurement is based on the intrinsic fluorescence of fluoroquinolones. Disk-based retention was performed after sample acidification (pH 4.0) by mixed-mode cation exchange using polystyrene divinylbenzene sulphonated sorbent. Sample loading was precisely controlled in a dedicated flow system operating at 4.0 mL min^?1. Different eluent compositions were tested, with elution performed by 1.00 mL of methanol-ammonium hydroxide (98:2, v/v), with subsequent reading of eluate in both detectors. Quantification was attained for 2–25 µg L^?1 range, with LOD values at 1 µg L^?1. The proposed approach was successfully applied to estuarine waters from the Douro River, with comparable results to a conventional SPE-LC-MS/MS procedure.     

On-line solid-phase extraction LC-MS/MS for the determination of Ac-SDKP peptide in human plasma from hemodialysis patients

We developed a high-throughput method based on on-line solid-phase extraction liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS) to determine N-terminal thymosin-β fragment peptide (N-acetyl-seryl-aspartyl-lysyl-proline, Ac-SDKP) in human plasma samples. Quantification of Ac-SDKP was performed using direct injection for on-line SPE based on C(18), reversed-phase LC separation and stable isotope dilution electrospray ionization-MS/MS in multiple reaction-monitoring (MRM) mode. The Ac-SDKP-(13)C(6), (15)N(2) (m/z 496 → 137) was synthesized for the internal standard. The MRM ion for Ac-SDKP was m/z 488 → 129 (quantitative ion)/226. The limit of detection and lower limit of quantitation were 0.05 and 0.1 ng/mL in standard solution, respectively. Recovery values were 98.3-100.4% with inter-day (relative standard deviation, RSD, 0.4-14.1%) and intra-day (RSD, 0.8-19.7%) assays. This method was applied to the measurement of Ac-SDKP levels in plasma from hemodialyzed subjects. Concentrations were 0.59 ± 0.23 ng/mL (pre-hemodialyzed subjects, n = 9) and 0.44 ± 0.19 ng/mL (post-hemodialyzed subjects, n = 9). All plasma Ac-SDKP levels were decreased by dialysis. Thus, plasma Ac-SDKP was decreased through dialysis in chronic kidney disease. The findings in this study will be useful for the treatment of anemia in chronic kidney disease with dialysis.     

Trimethylsilyldiazomethane derivatization coupled with solid-phase extraction for the determination of alendronate in human plasma by LC-MS/MS

Alendronate is an important representative of bisphosphonates, strongly polar compounds that lack chromophores. With rare exceptions, derivatization of the analytes is necessary for bioanalysis. In this study, a rapid liquid chromatography–tandem mass spectrometry method employing pre-column derivatization was developed and validated for the determination of alendronate concentrations in human plasma. The procedure was based on derivatization with trimethylsilyldiazomethane during solid-phase extraction on a weak anion-exchange solid-phase cartridge, which integrated sample purification and derivatization into one step. The alendronate derivative was eluted with methanol. Chromatographic separation was performed on a Capcell PAK-C18 column. The total run time was 6.5 min. The calibration curve was linear in the range 1.00–1,000 ng/mL using d6-alendronate as the internal standard. The lower limit of quantification was 1.00 ng/mL. The intra- and inter-assay precision (in RSD) calculated from quality control samples was less than 15%, and the accuracy was between 98.1% and 100.2%. The validated method was successfully applied to characterize the pharmacokinetic profiles of alendronate following the intravenous infusion of 5 or 10 mg alendronate sodium to healthy volunteers.     

基质固相分散萃取-高效液相色谱法同时测定五味子中5种木脂素类化合物北大核心CSCD

研究建立了基质固相分散萃取-高效液相色谱(MSPD-HPLC)分析五味子中5种木脂素类化合物(五味子醇甲、五味子醇乙、五味子甲素、五味子乙素、五味子丙素)的方法。采用反相C_(18)色谱柱进行分离,以0.1%(v/v)甲酸水溶液和乙腈为流动相进行梯度洗脱,在波长250 nm下检测。考察了包括硅胶、酸性氧化铝、中性氧化铝、碱性氧化铝、佛罗里硅土、Diol、XAmide、Xion和C_(18)、C_(18)-ME、C_(18)-G_(1)、C_(18)-HC等在内的12种吸附剂以及吸附剂的质量、洗脱剂的种类、洗脱剂体积对五味子木脂素类化合物得率的影响。选定Xion作为MSPD-HPLC分析五味子中木脂素类化合物的吸附剂;基于吸附剂Xion的萃取参数优化结果表明:以0.25 g五味子粉末为固定值,Xion(0.75 g)为吸附剂,甲醇(15 mL)为洗脱剂,MSPD对五味子中木脂素类化合物具有较高的得率。建立的五味子中5种木脂素类化合物的分析方法,各目标分析物具有良好的线性关系(相关系数R^(2)≥0.9999),检出限与定量限分别介于0.0089~0.0294μg/mL和0.0267~0.0882μg/mL之间。对五味子木脂素类化合物进行低、中、高3个水平的加标回收试验,平均回收率为92.2%~111.2%,相对标准偏差为0.23%~3.54%。日内和日间精密度均小于3.6%。与超声辅助提取和热回流提取前处理相比,MSPD具有萃取和净化相结合、耗时少、所需溶剂量少的优点,且MSPD-HPLC获得的结果优于经典方法。所建立的方法成功应用于17批五味子中5种木脂素类化合物含量的分析。     

基质固相分散-高效液相色谱法测定鲫鱼肌肉中残留的辛硫磷

建立了鲫鱼肌肉中残留的辛硫磷的基质固相分散-高效液相色谱-二极管阵列检测(MSPD-HPLC-DAD)的分析方法。通过优化样品处理条件,确定选取0.50 g鲫鱼肌肉样品与1.5 g弗罗里硅土、0.5 g无水硫酸钠混合研磨,并采用丙酮-正己烷溶液(体积比为40:60)为洗脱剂,洗脱剂用量为25 mL。优选的最佳色谱条件为：ODS色谱柱(250 mm×4.6 mm,5 μm),流动相为甲醇-水(体积比为50:50),流速0.6 mL/min,检测波长270 nm,进样量为20 μL。在上述条件下,辛硫磷质量浓度在0.01～10 mg/L范围内与响应信号呈良好的线性关系(r20.9994),检出限为3.3 μg/kg;相对标准偏差为1.1%～6.3%(n7);3个添加水平(0.05,0.1,1 mg/kg)下得到的回收率为88%～112%。该方法操作简单,耗时少,精密度高,符合农残分析的要求。     

液相色谱-串联质谱法测定牛奶中11种真菌毒素残留量

采用液相色谱-串联质谱法测定牛奶中11种真菌毒素的残留量。样品经乙腈沉淀蛋白和提取,正己烷脱脂,无水硫酸钠干燥,M160型多功能净化柱净化。以Agilent Eclipse XDB-C18色谱柱为分离柱,以不同体积比的水和甲醇混合液为流动相进行梯度洗脱,采用多反应监测模式检测。11种真菌毒素的质量分数均在4.0μg·kg-1以内与其峰面积呈线性关系,方法的检出限(3S/N)在0.001~0.006ng之间。加标回收率在60.1%~95.2%之间,测定值的相对标准偏差(n=6)在3.2%~9.6%之间。     

Determination of organochlorine pesticides in sewage sludge by matrix solid-phase dispersion and gas chromatography-mass spectrometry

A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 16 organochlorine pesticides (OCs) in sludge from municipal sewage plants. Samples of lyophilized sludge were blended with alumina, placed in small columns and OCs extracted with dichloromethane assisted by sonication. Purification of the extracts was accomplished by solid-phase extraction on C₁₈ columns and OCs were eluted with acetonitrile. Analyses were performed by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC–MS-SIM) using deuterated OCs as internal standards. The limits of detection were between 0.03 ng/g for 4,4′-DDE and 0.7 ng/g for endrin aldehyde.

Levels of OCs were determined in sewage sludge collected from 19 water treatment plants located in the province of Madrid (Spain). In all of the analyzed samples, aldrin was the compound most often found with a mean concentration of 76 ng/g. Endosulfan-I, -BHC, 4,4′-DDE and 4,4′-DDT were also present at high concentrations, with average values ranging from 32.3 to 74.3 ng/g. OCs were detected in all of the samples, with a total concentration ranging from 52 to 528 ng/g dry weight.     

Determination of sulfonamides in livers using matrix solid-phase dispersion extraction high-performance liquid chromatography

The matrix solid-phase dispersion (MSPD) was applied for extracting seven sulfonamides (SAs) in liver samples. The separation and determination were carried out by high-performance liquid chromatography. The analytes were derivated with fluorescamine and detected with fluorescence detector. The types of dispersion adsorbents for MSPD were examined and the highest recovery was obtained when the diatomaceous earth was used as the dispersion adsorbent and the mass ratio of dispersion adsorbent to sample was 3:1. The acetone was used as the elution solvent. Under the optimal conditions, the linear range for determining the SAs in liver samples was 5.0-1000.0 ng/g. The porcine, chicken and cattle liver samples were analyzed and the average recoveries of seven SAs were higher than 84.6%.     

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 phosmet and its metabolites in olives by matrix solid-phase dispersion and gas chromatography-mass spectrometry

An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spectrometry (GC/MS) was developed for determination of phosmet residues and its metabolites (phosmet-oxon, phthalimide, N-hydroxymethylphthalimide, and phthalic acid) in olive fruits. After testing different sorbents and eluents for MSPD extraction, C₁₈ and acetonitrile were found to be the most appropriate for clean-up of the samples, in terms of yields and efficient removal of interfering compounds. All analytes were determined in selective ion monitoring (SIM) mode following a derivatization step with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) containing 1% of trimethylchlorosilane (TMCS), except for phosmet and phosmet-oxon which were analyzed directly. The method showed suitable linearity (correlation coefficients higher than 0.8919 for all the compounds) and suitable sensitivity (limit of detection lower than 0.06 mg/kg). It was successfully applied in the analysis of olive fruits collected during the preharvest interval and olive oil. Phosmet residues found in all samples were lower than the maximum residue limits established by legislation (2 mg/kg).     

底物固相分散法测定土壤中甲氰菊酯残留量

以甲氰菊酯为分析对象，将一种新型的样品预处理技术-底物固相分散法(MSPD)应用于测定土壤中农药残留。确定了MSPD法的实验条件：土壤量为4g，水的加入量为1mL，固相吸附剂弗罗里硅土的用量为10．0g，淋洗剂为15mL石油醚-乙酸乙酯(1 9)。土壤样品在此条件下处理后无需进一步净化即可用气相色谱／电子捕获检定器测定。三种土壤的三种加标水平的回收率均在90％以上，相对标准偏差小于5％(n＝5)，最小检出质量比为0．002mg/kg。     

基质固相分散萃取和固相萃取-高效液相色谱-三重四极杆-复合线性离子阱质谱同时测定奶制品中6种雌激素

采用了基质固相分散萃取（MSPD）和固相萃取（SPE）技术分别对奶制品（奶粉和牛奶）中6种雌激素进行提取和净化。结果显示,MSPD适用于固体奶粉的处理,而SPE则适用于液体牛奶的处理。基于优化结果,利用高效液相色谱-三重四极杆-复合线性离子阱质谱（HPLC-Q-TRAP-MS）建立了在不同奶制品中同时测定6种雌激素含量的方法。方法学考察结果显示,建立的分析方法符合含量测定要求,在0.1~200 mg/L（雌三醇为0.1~20 mg/L）范围内线性关系良好（相关系数（R²）>0.99）;检出限（LOD,S/N=3）和定量限（LOQ,S/N=10）分别为0.01~0.05 mg/L和0.05~0.10 mg/L。在添加水平分别为1.0、5.0和10 mg/kg时,固态奶粉经MSPD处理后,6种雌激素的平均回收率为71.8%~106.0%（RSD为1.6%~9.2%,n=3）;液态牛奶经SPE处理后,6种雌激素的平均回收率为70.3%~108.4%（RSD为2.0%~11.0%,n=3）。该方法灵敏度和重复性高,适于分析复杂基质中雌激素的痕量残留。     

Two-dimensional coordination polymer matrix for solid-phase extraction of pesticide residues from plant Cordia salicifolia

The 2D coordination polymer (_∞[Gd(DPA)(HDPA)]) was tested for extraction of acephate, chlorpropham, pirimicarb, bifenthrin, tetradifon, and phosalone from the medicinal plant Cordia salicifolia, whose extracts are commercialized in Brazil as diuretic, appetite suppressant, and weight loss products, using GC/MS, SIM. Considering that there are no Brazilian regulations concerning maximum permissible pesticide residue concentrations in medicinal herbs, recovery experiments were carried out (seven replicates), at two arbitrary fortification levels (0.5 and 1.0 mg/kg), resulting in recoveries in range of 20 to 107.7% and SDRSDs were between 5.6 and 29.1% for _∞[Gd(DPA)(HDPA)] sorbent. Detection and quantification limits for herb ranged from 0.10 to 0.15 mg/kg and from 0.15 to 0.25 mg/kg, respectively, for the different pesticides studied. The developed method is linear over the range assayed, 0.5–10.0 μg/mL, with correlation coefficients ranging from 0.9975 to 0.9986 for all pesticides. Comparison between _∞[Gd(DPA)(HDPA)] sorbent and conventional sorbent (neutral alumina) showed similar performance of _∞[Gd(DPA)(HDPA)] polymeric sorbent for three (bifenthrin, tetradifon, and phosalone) out of six pesticides tested.     

基质固相萃取-气相色谱电子捕获检测器同时测定大米中12种有机氯农药残留量

建立了大米中12种有机氯农药气相色谱-电子捕获检测器检测方法.采用基质固相分散(Matrix Solid Phase Disperse, MSPD)技术进行样品前处理, 用气相色谱-电子捕获检测器进行快速定性定量分析.基质固相分散集提取、过滤、净化于一步完成, 避免了样品均化、转溶、乳化、浓缩造成的待测农药组分的损失, 大大提高了方法的准确度和精密度.12种有机氯农药的添加回收率在83%～103%之间,相对标准偏差为2.2%～19%.     

Coordination polymer adsorbent for matrix solid-phase dispersion extraction of pesticides during analysis of dehydrated Hyptis pectinata medicinal plant by GC/MS

The coordination polymer [Zn(BDC)(H₂O)₂]_n was tested for extraction of pyrimethanil, ametryn, dichlofluanid, tetraconazole, flumetralin, kresoxim-methyl and tebuconazole from the medicinal plant Hyptis pectinata, with analysis using gas chromatography-mass spectrometry in selected ion monitoring mode (GC/MS, SIM). Experiments carried out at different fortification levels (0.1, 0.5 and 1.0 μg g⁻¹) resulted in recoveries in the range 73-97%, and RSD values were between 5 and 12% for the [Zn(BDC)(H₂O)₂]_n sorbent. Detection and quantification limits ranged from 0.02 to 0.07 μg g⁻¹ and from 0.05 to 0.1 μg g⁻¹, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.04-14.0 μg g⁻¹), with correlation coefficients ranging from 0.9987 to 0.9998. Comparison between [Zn(BDC)(H₂O)₂]_n and the commercial phase C₁₈-bonded silica showed good performance of the [Zn(BDC)(H₂O)₂]_n polymeric sorbent for the pesticides tested.     

Molecularly imprinted matrix solid-phase dispersion for extraction of chloramphenicol in fish tissues coupled with high-performance liquid chromatography determination

The synthesis and evaluation of a molecularly imprinted polymer (MIP) as a selective matrix solid-phase dispersion (MSPD) sorbent, coupled with high-performance liquid chromatography for the efficient determination of chloramphenicol (CAP) in fish tissues are studied. The polymer was prepared using CAP as the template molecule, vinylpyridine as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer, and sodium dodecyl sulfate as the surfactant in the presence of water as a solvent by miniemulsion polymerization. The CAP-imprinted polymers and nonimprinted polymers (NIPs) were characterized by Fourier transform IR spectroscopy, scanning electron microscopy, and static adsorption experiments. The CAP-imprinted material prepared showed high adsorption capacity, significant selectivity, and good site accessibility. The maximum static adsorption capacity of the CAP-imprinted and the NIP material for CAP was 78.4 and 59.9 mg g(-1), respectively. The relative selectivity factors of this CAP-imprinted material were larger than 1.9. Several parameters influencing the MSPD process were optimized. Finally, the CAP-imprinted polymers were used as the sorbent in MSPD to determine CAP in three kinds of fishes and resulted in satisfactory recovery in the range 89.8-101.43%. CAP-imprinted polymer as a sorbent in MSPD is better than C18 and attapulgite in terms of both recovery and percent relative standard deviation. The baseline noise was measured from a chromatogram of a blank fish sample which was treated after the MSPD procedure using CAP-imprinted polymer as a sorbent. Signal values of 3 times the noise (signal-to-noise ratio of 3) and 10 times the noise (signal-to-noise ratio of 10) were used to calculate the limit of detection and the limit of quantitation of the calibration curve. The limit of detection for CAP was 1.2 ng g(-1) and the limit of quantitation was 3.9 ng g(-1).