Liquid chromatography-tandem mass spectrometry determination of N-nitrosamines released from rubber or elastomer teats and soothers

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method as an alternative to a gas chromatography-thermal energy analyser (GC-TEA) method recommended by the European Committee on Standardization (CEN) was validated for the simultaneous determination of eight N-nitrosamines released into artificial saliva from rubber or elastomer teats and soothers. N-nitroso-dipropylamine-d₁₄ (NDPA-d₁₄) was used as internal standard for accurate quantification. The method was validated with relatively good analytical results, including sufficiently low limits of detection (0.1–2?µg?kg^?1 of sample) and good linearity (r ^2?>?0.99) throughout the studied concentration ranges. Intra- and inter-day precisions expressed with the relative standard deviation (RSD, %) were 3.4–8.0% and 4.4–11.3%, which were below the performance criteria based on one-half of the value derived from the Horwitz value. It was also found that the LC-MS/MS method is sufficiently rugged and successfully applicable to its routine analysis for the compliance test of Commission Directive 93/11/EEC.     

液相色谱-串联质谱法测定腐乳中的生物胺

建立了一种使用液相色谱-串联质谱（LC-MS/MS）技术检测腐乳中9种生物胺的方法。样品经5%三氯乙酸水溶液提取后,进行液相色谱-串联质谱法测定,采用外标法定量。对检测方法进行方法学验证,9种生物胺在质量浓度为10～200 ng/mL范围内线性相关系数R2＞0.999,方法检出限为0.03 mg/kg,定量限为0.1 mg/kg,回收率在85%～101%之间,相对标准偏差（RSD）在0.9%～4.8%之间。该方法结果精密、准确、重复性好、操作简单,适用于腐乳中9种生物胺的测定。     

液相色谱法及液相色谱-串联质谱法测定山楂及其制品中展青霉素的结果比较与建议

目的比较液相色谱法(liquidchromatography,LC)和液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry, LC-MS/MS)测定山楂及其制品中展青霉素的方法学指标。方法 LC法:山楂及固体制品经粉碎酶解后,用乙酸乙酯提取,Mycosep?228Aflapat净化柱净化浓缩,以乙腈和水作为流动相进行梯度洗脱,液相色谱仪被测定; LC-MS/MS法:样品处理方法同LC法(除加同位素外),以乙腈和水作为流动相进行梯度洗脱,外标法定量,采用电喷雾离子源负模式测定。结果 LC法和LC-MS/MS法展青霉素在10～200 ng/mL浓度内线性良好,相关系数均大于0.9999; LC法的回收率为96.12%～104.20%, RSD均小于2.5%,检出限为0.52～0.63μg/kg,定量限为1.7～2.0μg/kg; LC-MS/MS法的回收率为94.68%～103.59%, RSD均小于2.5%,检出限为0.12～0.39μg/kg,定量限为0.38～1.29μg/kg。结论 2种方法结果无显著差异,均可适用于山楂及山楂制品中展青霉素的测定。     

茶叶中10种农药残留的液相色谱-串联质谱法和气相色谱-串联质谱法测定

建立了茶叶中啶虫脒、乐果、吡虫啉、灭多威、甲基嘧啶磷、腐霉利共6种农药残留的液相色谱-串联质谱(LC-MS/MS)测定方法和溴氰菊酯、乐果、高效氯氟氰菊酯、p,p'-滴滴伊、甲基嘧啶磷、腐霉利、哒螨灵共7种农药残留的气相色谱-串联质谱(GC-MS/MS)测定方法。其中,乐果、甲基嘧啶磷和腐霉利三种农药均能通过两种方法测定。LC-MS/MS法测定的6种农药,在5~200 μg/L范围内线性关系良好(R2>0.995),在10、50、100 μg/kg加标水平下的回收率为70.0%~105.0%,相对标准偏差为0.3%~18.7%。GC-MS/MS法测定的7种农药,在10~500 μg/L范围内线性关系良好(R2>0.996),在10、50、300 μg/kg加标水平下的回收率为82.0%~110.0%,相对标准偏差为1.8%~12.0%。该方法完善了茶叶中10种农药残留检测方法针对实际样品的检测,灵敏度满足国外限量标准要求,适合出口茶叶中农药残留的测定。     

In-house validation of an ELISA method for screening of semicarbazide in eggs

An enzyme-linked immunosorbent assay (ELISA) method is described for the semi-quantitative determination of semicarbazide (SEM), the marker residue for the banned nitrofuran drug, nitrofurazone, in chicken eggs. The sample homogenate is subjected to acid hydrolysis and derivatisation with o-nitrobenzaldehyde, followed by ethyl acetate/hexane extraction and detection by ELISA. The ELISA procedure has been validated using 0.3, 1.0 and 3 microg kg(-1) of SEM in fortified samples. Detection capability (CC(ss)) was based on the acceptance of 5% false compliant results for a given concentration level according to Commission Decision 2002/657/EC and was determined to be 0.3 microg kg(-1) with a respective limit of detection of 0.13 microg kg(-1). A validated LC-MS/MS method was used for the analysis of incurred egg samples and the results compared with ELISA. A good correlation between the results obtained from ELISA and LC-MS/MS within the concentration range 0.12-20.3 microg kg(-1) was observed in samples collected from chickens fed with a medicated ration of nitrofurazone (r = 0.992, n = 14). Validated ELISA enabled reliable monitoring of SEM levels in eggs collected from incurred chickens over a 90-day period.     

酶联免疫法与液相色谱-串联质谱法检测猪肉中沙丁胺醇

运用酶联免疫法（ELISA）与液相色谱-串联质谱法（LC-MS/MS）对猪肉中沙丁胺醇残留进行测定,并比较了二者在灵敏度、准确性和重现性等方面的差异。结果显示,ELISA法和LC-MS/MS法在猪肉样品中的检测限可达到0.5 μg/kg和0.25 μg/kg,分别向猪肉样品中添加3个质量浓度水平（1.0 μg/kg、2.0 μg/kg、4.0 μg/kg）的沙丁胺醇时,回收率分别为83.7%～90.9%和86.6%～93.5%,变异系数（CV）分别为5.4%～10.3%和6.0%～8.3%。用酶联免疫法实际样品进行检测,筛选出2个阳性样品,经液相色谱-串联质谱法确证亦为阳性,测定结果一致。研究表明,酶联免疫法重复性较好、准确度较高,适用于进行猪肉样品中沙丁胺醇的快速筛选,液相色谱-串联质谱法适用于阳性样品的确证和精确定量。     

UNE-EN ISO/IEC 17025:2005-accredited method for the determination of pesticide residues in fruit and vegetable samples by LC-MS/MS

A rapid, simple and sensitive multi-residue method was developed and validated for the simultaneous quantification and confirmation of 69 pesticides in fruit and vegetables using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted following the quick, easy, cheap, effective, rugged and safe method known as QuEChERS. Mass spectrometric conditions were individually optimised for each analyte in order to achieve maximum sensitivity in multiple reaction monitoring (MRM) mode. Using the developed chromatographic conditions, 69 pesticides can be separated in less than 17 min. Two selected reaction monitoring (SRM) assays were used for each pesticide to obtain simultaneous quantification and identification in one run. With this method in SRM mode, more than 150 pesticides can be analysed and quantified, but their confirmation is not possible in all cases according to the European regulations on pesticide residues. Nine common representative matrices (zucchini, melon, cucumber, watermelon, tomato, garlic, eggplant, lettuce and pepper) were selected to investigate the effect of different matrices on recovery and precision. Mean recoveries ranged from 70% to 120%, with relative standard deviations (RSDs) lower than 20% for all the pesticides. The proposed method was applied to the analysis of more than 2000 vegetable samples from the extensive greenhouse cultivation in the province of Almería, Spain, during one year. The methodology combines the advantages of both QuEChERS and LC-MS/MS producing a very rapid, sensitive, accurate and reliable procedure that can be applied in routine analytical laboratories. The method was validated and accredited according to UNE-EN-ISO/IEC 17025:2005 international standard (accreditation number 278/LE1027).     

基于液相色谱-串联质谱法纺织品中三氯生的普查分析

建立了液相色谱-串联质谱法（LC-MS/MS）测定五大类纺织品中三氯生的检测方法,并对市场上随机抽取的15种样品进行了普查分析。样品采用三氯甲烷超声提取,提取后的溶液经过滤、浓缩后,采用LC-MS/MS检测,选择离子模式（SIM）扫描,外标法定量。该方法的在0.01～0.5?g/mL范围内有很好的线性关系,线性方程为：y=3.5e4x-994,线性相关系数为0.9998,方法的测定低限为0.025 mg/L,平均回收率为85.6～107.2 %,相对标准偏差小于7.0%。在所有样品中仅有2个样品检出,表明在纺织品中仍会添加三氯生。     

Analysis of chloramphenicol in honeys of different geographical origin by liquid chromatography coupled to electrospray ionization tandem mass spectrometry.

A sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to detect trace amounts of the antibiotic chloramphenicol (CAP) in honey. The methodology entailed a solid-phase extraction of aqueous honey solutions followed by liquid-liquid partitioning, filtration and direct injection onto the LC-MS/MS system. Honey extracts were spiked with an isotopically labelled internal standard (d(5)-CAP) to compensate for analyte loss and potential ion suppression during the MS stage. Detection of the analyte was achieved by negative ionization electrospray in the selected reaction monitoring (SAM) mode. For confirmation, four characteristic mass transitions were monitored each for the analyte and the surrogate standard. The method was validated according to the latest European Union criteria for the analyses of veterinary drug residues in food. At all three fortification levels studied (0.1, 0.2, 0.5 microg kg(-1)) the method was accurate to within 15%. The repeatability and within-laboratory reproducibilities were <12 and 18%, respectively. The decision limit (CC alpha) and detection capability (CC beta) were both <0.1 microg kg(-1). The procedure provides a sensitive and reliable method for the determination of residues of chloramphenicol in honey. Numerous raw honeys of various geographical origins were analysed, showing extensive contamination particularly those of Chinese origin.     

GC-MS和LC-MS/MS分析麦粉中烷基间苯二酚同系物组成

建立气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用法和液相色谱-串联质谱（liquid chromatography-tandem mass spectrometry,LC-MS/MS）法测定麦粉中烷基间苯二酚组成。样品经乙酸乙酯超声提取,在GC-MS中,硅烷化衍生处理,采用选择离子监测模式进行测定,以外标法进行定量;在LC-MS/MS中,经固相萃取富集净化,以C18色谱柱分离,采用电喷雾负离子模式扫描、多反应监测模式检测,以外标法进行定量。结果表明,GC-MS和LC-MS/MS均在0.001～5 μg/mL质量浓度范围内有良好的线性关系（R2＞0.98）,GC-MS法的检出限为2.0～6.1 μg/g,加标回收率在94.17%～99.15%之间,相对标准偏差（relative standard deviation,RSD）在2.94%～4.87%之间;LC-MS/MS法的检出限为2.0～8.4 μg/g,加标回收率在89.05%～99.06%之间,RSD在2.21%～4.17%之间。本研究建立了2 种线性关系良好、低检测限、高灵敏度的检测方法,均可适用于市售麦粉产品中烷基间苯二酚同系物定性定量分析,将为麦类全谷物产品品质控制与检测提供技术指导。     

Determination of pindone in agricultural products by LC-MS/MS

A sensitive and selective analytical method for the determination of pindone in agricultural products by LC-MS/MS was developed. Pindone was extracted with acetone, and an aliquot of the crude extract was re-extracted with hexane. For lipid-rich samples, the crude extract was further cleaned up by acetonitrile-hexane partitioning. The extract was cleaned up on a tandem graphitized carbon-silica gel column. For brown rice, soybean, and tea, PSA column cleanup was added prior to LC-MS/MS determination. Average recoveries of pindone from brown rice, soybean, potato, spinach, cabbage, apple, orange, tomato, cucumber, and tea fortified at 0.001 mg/kg were 81-93%, and the relative standard deviations were 2-7%. The limit of quantitation (S/N ≥ 10) of the developed method was 0.001 mg/kg for all the tested agricultural products.     

Quantification of staphylococcal enterotoxin type A in cow milk by using a stable isotope-labelled peptide via liquid chromatography–tandem mass spectrometry

ABSTRACT

In this study, the staphylococcal enterotoxin type A (SEA) contaminant was quantified in cow milk by liquid chromatography–tandem mass spectrometry (LC–MS/MS) with the use of a stable isotope-labelled peptide of SEA as an internal standard. SEA was cleaned up in a two-step process that included pH control and trichloroacetic acid (TCA) precipitation. The pH control phase eliminated other proteins. TCA precipitation cleaned up SEA without special equipment. An appropriate enzyme-to-protein ratio maximised tryptic digestion. A desalting process guaranteed the stable retention of SEA-digested peptides. The coverage of amino-acid sequences (>10%) clearly identified the toxin’s presence. SEA was accurately quantified using LC-MS/MS based on a multiple-reaction monitoring mode. The developed method was validated based on spiked recovery tests at 50 and 100 µg kg^?1 conducted with two samples collected on a daily basis for five days based on Japanese validation guidelines. The new method exhibited good accuracy which ranged from 80% to 82%. The relative standard deviations of repeatability were 13–14% and the relative standard deviations of within-laboratory reproducibility were 13–18%. These standard deviations satisfied the criteria of the Japanese validation guidelines. The quantification limit was estimated to be 10 µg kg^?1.     

液相色谱串联质谱测定动物源性食品中孕激素类药物残留

本文以常见的肉制品为研究对象,建立并优化了经过固相萃取小柱净化,结合LC-MS/MS测定肉制品中8种孕激素残留量的方法.样品经过酶解提取,之后经C18小柱净化后,采用液相色谱串联质谱对孕激素进行检测分析.结果表明,8种孕激素分离效果好,检出限(LOD)为0.01-0.05 μg/kg,相对标准偏差＜4.0％(n = 6...     

液相色谱-串联质谱法测定山银花中有机酸和黄酮类化合物的含量

本文通过甲醇溶液超声提取,HLB固相萃取柱净化,液相色谱-串联质谱法检测,建立了山银花中4种有机酸(绿原酸、咖啡酸、异绿原酸A和异绿原酸C)和14种黄酮类化合物(槲皮素、芦丁、木犀草素、木犀草苷、山奈酚、紫云英苷、芹菜素、野漆树苷、黄芩素、黄芩苷、槲皮素-3-甲基醚、香叶木素、白杨素和山奈素)含量测定的方法。山银花样品经50%的甲醇溶液超声提取40分钟,HLB固相萃取柱净化,采用Mightysil RP-18色谱柱分离,液相色谱-串联质谱法进行检测(电喷雾离子源,多反应监测模式,负离子扫描),外标法定量进行测定。方法定量限(以S/N大于10计)0.005 g/kg-0.05 g/kg,配制0.05、0.10、0.20、0.50和1.00 g/kg线性工作曲线,线性相关系数大于0.993。在山银花样品中进行添加回收试验(添加水平绿原酸10.0、20.0和40.0 g/kg,咖啡酸1.0、2.0和4.0 g/kg,异绿原酸A和异绿原酸C 5.0、10.0和20.0 g/kg,其他化合物0.05、0.10和0.20 g/kg),方法总体回收率69.2%~116%,相对标准偏差3.3%~12.0%。方法实现了山银花中多种主要有机酸和黄酮类化合物含量的同时测定。     

LC-MS/MS法测定烟草中7种高级脂肪酸

为快速、准确检测烟草中高级脂肪酸含量,建立了测定烟草中7种高级脂肪酸的液相色谱-串联质谱（LC-MS/MS）方法。样品经KOH的甲醇溶液皂化,二氯甲烷萃取后,十七烷酸作内标直接进样LC-MS/MS分析定量。结果表明各高级脂肪酸峰面积与内标峰面积的比值和其浓度与内标浓度之比的线性关系良好（R2 ≥ 0.9818）,加标回收率在87.5% ~ 109%之间,平均相对标准偏差（RSD）在1.1%~4.7%之间,方法的检出限（LOD）和定量限（LOQ）分别为0.0004~ 0.007 mg/g和0.001~0.02 mg/g。该方法适用于烟草7种高级脂肪酸的快速测定,具有简单、快速、灵敏等特点。      

LC-MS/MS法测定食用油中的辣椒素和二氢辣椒素

建立了用氨基固相萃取小柱净化提取液,液相色谱串联质谱（LC-MS/MS）法测定食用油中辣椒素和二氢辣椒素含量的检测方法。结果表明,辣椒素在0～100 ng/mL范围内线性关系良好（R2 = 0.998 6）,平均回收率在70.6%～90.5%,相对标准偏差（RSD,n=3）在3.1%～8.9%,检出限为0.03 μg/kg;二氢辣椒素在0～20 ng/mL范围内线性关系良好（R2 = 0.998 8）,平均回收率在71.5%～100.7%,相对标准偏差（RSD,n=3）在6.0%～13.2%,检出限为0.006 μg/kg。该方法简便快速、准确可靠,是鉴别地沟油和测定食用油中辣椒素类物质的有效方法。     

Sensitive isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry method for the determination of acrylamide in chocolate.

Isotope dilution liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) was applied to the quantification of acrylamide in chocolate matrixes (dark chocolate, milk chocolate, chocolate with nuts, chocolate with almonds, and chocolate with wheat best element). The method included defatting with petroleum ether, extracting with aqueous solution of 2 mol l(-1) sodium chloride and clean-up by solid-phase (SPE) with OASIS HLB 6 cm3 cartridges. Acrylamide was detected with an Atlantis dC18 5 microm 210 x 1.5 mm column using 10% methanol/0.1% formic acid in water as the mobile phase. The analytical method was in-house validated and good results were obtained with respect to repeatability (RSD < 3.5%) and recovery (86-93%), which fulfilled the requirements defined by European Union legislation. The acrylamide levels in chocolate were 23-537 microg kg(-1). Therefore, the method was successfully used for the quantitative analysis of acrlyamide in various chocolate products.     

LC-MS/MS法测定水基胶中的3种异噻唑啉酮类防腐剂

建立了测定水基胶中3 种异噻唑啉酮的液相色谱-串联质谱(LC-MS/MS)方法。水基胶样品经水萃取、离心后进行LCMS/MS 分析,内标法定量。结果表明:MI、CMI 在浓度范围2.5~250 ng/mL、BIT 在浓度范围5~500 ng/mL 内,线性关系良好(R2 ≥ 0.9996),3 个加标水平的加标回收率在96.3%~109.6% 之间,平均相对标准偏差(RSD)在1.5%~6.7% 之间,方法的检出限(LOD)和定量限(LOQ)分别为0.011~0.015 mg/kg 和0.035~0.051 mg/kg。该方法适用于水基胶中MI、CMI、BIT 的快速测定。      

液相色谱串联质谱法测定肉中丙硫咪唑及其代谢物

建立同时测定肉中丙硫咪唑及其代谢物丙硫咪唑砜、丙硫咪唑亚砜、2-氨基丙硫咪唑砜的液相色谱串联质谱法。样品用乙腈提取,液液分配净化后,XDB-C18色谱柱分离,流动相乙腈:0.1%甲酸溶液(1:1,V/V),外标法定量。丙硫咪唑及其3种代谢物的检出限均为0.010mg/kg,在0.010～1.0mg/L范围内其质量浓度与峰面积呈良好的线性关系,相关系数大于0.99。添加量为0.010～0.050mg/kg时的回收率为82.3%～97.6%,相对标准偏差为4.9%～12.9%。该方法简便、快速、准确,可用于猪肉、牛肉、羊肉、鸡肉、香肠中丙硫咪唑及其代谢物的定性、定量检测。     

Analysis for perfluorocarboxylic acids/anions in surface waters and precipitation using GC--MS and analysis of PFOA from large-volume samples

The presence of perfluorocarboxylates (PFCAs) in the environment is of increasing concern, following the discovery of perfluoroalkyl acids (PFAs) in wildlife and human samples. Here we report a method forthe determination of (C2-C9) PFCAs by preparing the 2,4-difluoroanilides of the acids and analyzing by using GC-MS. Detector response was linear over the range 0.1 -1000 pg of each perfluoroalkyl anilide. A complete suite of PFCAs can be analyzed in an individual sample with the PFCAs detected at levels similar to or lower than those determined by other methods. For a comparison between the present method and the more common LC-MS/MS method, 10 replicates of a sewage treatment plant discharge were analyzed for perfluoro-octanoic acid (PFOA) using both methods. Results were nearly identical with low standard deviation (GC-MS 30.9 +/- 1.88 ng/L; while the LC-MS/MS 34.7 +/- 3.05 ng/L). PFCA concentrations for water samples collected from depth profiles in mid-Lake Ontario were analyzed by GC-MS with most PFCAs (C2-C8) present above the detection limit (0.5 ng/L). Major PFCAs were trifluoroacetate (TFA) (100 ng/L) and perfluorobutanoate (PFBA) (> 5 ng/L). Results for PFOA (2.5 ng/L) were in good agreement with recent analyses by LC-MS/MS. PFCAs were also detected in the precipitation samples at concentrations lower than those of the samples from the lake profiles or sewage treatment plants (STPs) effluent. Since PFOA levels may be less than the lower detection limit (<0.5 ng/L) in 1 L samples, a method for large volumes using XAD-7 resin was developed that allows detection to 0.01 ng/L. This method was applied to Lake Superior samples which produced good agreement for C6-C9 PFCAs between regular analysis (GC-MS) and the XAD-7 followed by GC-MS analysis.