Multiresidue method for pesticides and veterinary drugs in bovine milk using GC/MS and LC/MS/MS

A simple, sensitive and selective method with gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been developed to detect 342 pesticides and veterinary drugs contaminating bovine milk at the maximum residue limits (MRLs) defined in the "positive list system". Sample preparation was performed by extracting the analytes with acetonitrile, followed by salting-out with sodium chloride. For some pesticides, the extract was further cleaned up by n-hexane partitioning and PSA cartridge column chromatography. GC/MS-EI or -NCI was used to determine pesticide residues, while LC/MS/MS-ESI was applicable to the determination of pesticide and veterinary drug residues. The variation of the recoveries of these drugs at MRL was relatively wide; however the relative standard deviations of the recovery of each drug were within 28%, suggesting that the present method is good enough for use as a screening test for contaminants at the MRLs. These results show that this method is useful for multiresidue analysis of numerous pesticides and veterinary drugs in bovine milk.     

Simultaneous determination of sedecamycin and terdecamycin in livestock products by LC/MS

A simple and rapid LC/MS method for simultaneous determination of sedecamyin (SCM) and terdecamycin (TDM) in livestock products has been developed. SCM and TDM were extracted with acetonitrile. The extract was washed with n-hexane and then evaporated to dryness. The residue was dissolved in methanol, and injected into the LC/MS. The mass spectrometer was operated in the positive electrospray ionization (ESI) mode. LC separation was performed on a high-pH-resistant C18 column with 10 mmol/L carbonic acid-ammonia buffer (pH 10.0)-acetonitrile as a mobile pahse. The recoveries from swine muscle and liver fortified at the levels of 0.01 and 0.05 microg/g were 77-88%, and those from poultry muscle and liver fortified at the levels of 0.01 and 0.3 microg/g were 51-93%. The quantitation limits of SCM and TDM were 0.008 microg/g and 0.005 microg/g, respectively.     

Determination method for ractopamine in swine and cattle tissues using LC/MS

Simple and reliable methods using LC/MS have been developed for the determination of the beta-agonist ractopamine in swine and cattle tissues. Ractopamine was extracted with ethyl acetate from muscle and liver, and the ethyl acetate layer was evaporated to dryness. The residue was purified by partition with acetonitrile/n-hexane. In the case of fat, ractopamine was extracted and purified by partition with acetonitrile/n-hexane. The resulting acetonitrile solutions were evaporated to dryness. The residue was dissolved in methanol, and subjected to LC/MS. The LC separation was performed on a Wakosil-II 3C18HG column (150 x 3 mm i.d.) in isocratic mode with 0.05% trifluoroacetic acid-acetonitrile (80:20) as a mobile phase at a flow rate of 0.4 mL/min. The MS detection was performed in the selected ion recording (SIR) mode, with detection of the M + H+ ion of ractopamine (m/z 302) produced by electrospray ionization (ESI). The mean recoveries of the drug from swine muscle (0.01 microg fortified), fat (0.01 microg fortified) and liver (0.04 microg/g fortified) were 99.7%, 99.5% and 100.8%, and those from cattle samples were 108.3%, 97.0% and 109.4%, respectively. The relative standard deviations (RSDs) ranged from 0.1% to 9.5%. The limit of quantification (LOQ) of the drug was 1 ng/g.     

Simple preprocessing method for multi-determination of 235 pesticide residues in cooked ingredients of foods by GC/MS and LC/MS/MS

A simple preprocessing method was developed for multiresidue determination of pesticides in processed agricultural products. Residues were extracted from homogenized samples with acetonitrile in a glass centrifuge tube, followed by salting-out and partitioning with n-hexane. Co-extractives were removed by means of mini-column clean up. Analysis was performed by GC/MS and LC/MS/MS. The prepared sample solutions were examined for matrix effects. Matrix effects had both positive and negative effects on quantitative value. Calibration was achieved by preparing matrix-matched calibration standards to counteract the matrix effects. Of the 235 pesticides spiked at 0.05 or 0.10 microg/g (Method GC), 0.025 or 0.05 microg/g (Method LC) into 8 foods (garlic paste, diced green sweet pepper, green peas paste, celery paste, sweet potato paste, dried adzuki beans, boiled bamboo shoots, tomato paste), recoveries of 214 pesticides were between 50 and 100% and the coefficient of variation was below 20%. This method is useful as a multi-residue analysis method for screening of pesticides in foods.     

Simultaneous determination of pesticides in agricultural products by LC/MS/MS using clean-up with ultrafiltration

A method for simultaneous determination of multiple pesticide residues in agricultural products was developed by using a pretreatment with ultrafiltration, followed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The pretreatment process (extraction of pesticides from agricultural products with methanol, dilution of the extract with water, and ultrafiltration) gave recoveries in the range of 50-150% for 63 of 83 pesticides spiked at 0.25 microg/ g into 6 agricultural products. The detection limits of pesticides by LC/MS/MS were below 0.0005-0.05 micro/g. This method is useful for screening purposes and for multiresidue analysis of pesticides in agricultural products. Pesticide residues in 50 domestic crops were investigated by this method, and residues of 14 pesticides were detected in 30 crops.     

Simultaneous determination of quinolones in foods by LC/MS/MS

A simple method was developed for the simultaneous determination of seven quinolones (enoxacin, ofloxacin, ciprofloxacin, danofloxacin, lomefloxacin, enrofloxacin and sarafloxacin) in foods using liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The seven quinolones were extracted with acetonitrile containing 0.2% formic acid, and the extracted solution was cleaned up on a C18 cartridge. The extract was diluted with 5 mmol/L IPCC-MS3 for injection into the LC-ESI-MS/MS. The LC separation was carried out on an ODS column with gradient elution of 5 mmol/L IPCC-MS3-acetonitrile as the mobile phase. Mass spectral acquisition was done in the positive ion mode by applying selected reaction monitoring (SRM). The recoveries of the seven quinolones were mostly greater than 60% from foods fortified at 10 ng/g. The detection limits in foods were 2 ng/g for enoxacin and ciprofloxacin, and 1 ng/g for the other drugs. Twenty cattle muscle, 7 swine muscle, 9 chicken muscle, 16 milk, 19 prawn and 20 broiled eel samples from retail markets were analyzed by this method. Enrofloxacin and its metabolite ciprofloxacin were detected in 9 broiled eel at the level of trace (tr)-34 ng/g and tr-10 ng/g, respectively.     

Analytical method of clofencet in animal fishery products by LC/MS

A method for the determination of clofencet in animal and fishery products was developed, using liquid chromatography with electrospray ionization mass spectrometry (LC/ESI-MS). The sample was homogenized with water and hexane, and the homogenate was extracted with acetonitrile, then acetonitrile-water (4 : 1). An aliquot of the crude extract was passed through a C18 cartridge column (1,000 mg), and the eluate was concentrated. A solution of 10% sodium chloride and 1% sodium hydrogen carbonate, and ethyl acetate were added to the residue, and the mixture was shaken. After shaking, the aqueous phase was recovered and acidified with hydrochloric acid, and then clofencet was extracted with ethyl acetate. The extract was evaporated to dryness and the residue was dissolved in methanol-water (3 : 7). Clofencet was analyzed by LC/MS. The recoveries of clofencet from ten kinds of animal and fishery products were 77.8-97.8%, and the relative standard deviations were 0.6-5.8% (n=5). S/N of the peak of clofencet was >10 and no interfering peak was found in animal and fishery products fortified at 0.01 mg/kg.     

QuEChERS结合GC-MS/MS法测定果蔬汁中21种农药残留

建立一种采用QuEChERS前处理结合Quick Pro净化柱-气相色谱串联质谱（GC-MS/MS）法测定果蔬汁中的21种农药残留量的方法。样品采用乙腈提取,EN方法盐包盐析,经Quick Pro净化柱净化,DB-35MS UI色谱柱分离,采用选择离子监测（SIM）模式扫描,外标法定量。在质量浓度0.01～0.50 μg/mL范围内相关系数（R）均＞0.995,样品在0.01 mg/kg、0.02 mg/kg、0.10 mg/kg的添加水平下,21种农药的回收率在75.2%～117.8%之间,回收率实验结果相对标准偏差（RSD）在1.9%～11.5%之间。该方法操作简便,分析时间短,精密度好,适用于果蔬汁中多种农药残留的检测。     

Analytical method of hydramethylnon in agricultural products by LC-MS/MS

A simple determination method of hydramethylnon in agricultural products by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The sample was homogenized with phosphoric acid and extracted with acetone. An aliquot of crude extract was re-extracted with hexane and sat. NaCl solution. In the case of tea leaf, solidification processing using ammonium chloride and phosphoric acid was performed before re-extraction with hexane. Clean-up was performed using a silica-gel mini column (500 mg). The LC separation was performed on a C18 column using methanol-water (8 : 2) containing 10 mM ammonium acetate as the mobile phase and MS detection with positive ion electrospray ionization. The calibration curve was linear between 0.002-0.2 μg/mL of hydramethylnon. Recoveries (n=5) of hydromethylnon from 10 kinds of agricultural products fortified at 0.01 μg/g (0.05 μg/g for pineapple) were 82-110%, and their relative standard deviations were 2-12%.     

QuEChERS结合液相色谱-串联质谱法测定食用菌中13种农药残留

目的:建立并应用QuEChERS结合液相色谱-串联质谱法测定食用菌中13种农药残留。方法:样品5.0 g用乙腈-水(4:1)15 mL超声提取,经N-丙基乙二胺(PSA)30.0 mg和无水硫酸镁15.0 mg分散固相萃取吸附剂净化。使用HSS T3色谱柱,0.1%甲酸和乙腈为流动相梯度洗脱。质谱采用电喷雾正离子源和多反应监测模式。结果:13种农药的质量浓度在0.5~200 μg/L范围内与峰面积呈良好的线性关系,检出限(S/N=3)0.03~0.3 μg/kg。加标回收率84.3%~102%,相对标准偏差(n=6)2.8%~6.3%。结论:该方法可用于食用菌中13种农药残留的检测。     

Multiresidue method for determination of pesticides in fruits and vegetables by GC/MS (SCAN) and LC/MS (SIM)

A rapid multiresidue method has been developed for determination of many pesticides in fruits and vegetables using GC/MS and LC/MS. The method of analysis was the same as that reported by Kakimoto et al. in 2003 except for the use of LC/MS. Good recoveries in the range of 70-120% were obtained for 70 (32 by GC/MS, 38 by LC/MS) of 113 pesticides spiked at 0.1 microg/g into fruits and vegetables. For screening purposes, the method could be appiled to 82 pesticides. Considering the report by Kakimoto et al. in 2004, 177 pesticides were suitable for screening by this method. The limits of detection were 0.001-0.015 microg/g (by GC/MS) and < 0.001-0.010 microg/g (by LC/MS). The calibration curves were linear for most pesticides, with correlation coefficients of 0.976-1.000 (by GC/MS) and 0.968-1.000 (by LC/MS). The values obtained for fruits and vegetables naturally contaminated with pesticides by this method were nearly equal to those by the official method.     

气相色谱-串联质谱法测定鲜猴头菇中16种农药残留

建立气相色谱-串联质谱（GC-MS/MS）法测定猴头菇中16种农药残留的定性、定量分析检测方法。样品经乙腈旋涡振荡提取、净化、浓缩、过滤、定容后,采用气相色谱串联质谱进行定性、定量检测分析。结果表明,16种农药在质量浓度为0.05～1.00 μg/mL范围内的线性关系良好,相关系数（R2）为0.998 6～0.999 9。在猴头菇样品中分别添加质量浓度为0.05 mg/kg、0.20 mg/kg、0.40 mg/kg的混合农药组分,平均回收率为86.08%～93.63%,相对标准偏差（RSD）为3.96%～8.92%,检出限为0.010～0.075 mg/kg。该法操作便捷、灵敏度高、回收率良好、精密度可靠,适用于猴头菇中多种有机农药残留的同时检测。     

Simultaneous determination of veterinary drugs in livestock foods and seafoods using liquid chromatography/tandem mass spectrometry

A simultaneous determination of veterinary drugs in livestock food and seafood using liquid chromatography with tandem mass spectrometry (LC/MS/MS) was developed. Veterinary drugs were extracted with 95% acetonitrile. The solution was passed through a Florisil column, and the solvent was replaced with phosphate buffer. The extract was charged on a Sep-Pak Plus C(18) mini-column and divided into 40% methanol eluate fraction and 70% acetonitrile eluate fraction. Test solutions were analyzed by LC/MS/MS with gradient elution. By using this method, 37 kinds of veterinary drugs were obtained with over 60% recovery, and quantitation was possible in cattle muscle, egg and fish. This method was inapplicable to 28 kinds of veterinary drugs. Although quantitation was not achieved, 42 other kinds of veterinary drugs can be screened. Since the limit of quantitation for this method is less than the provisional limit in general, it is useful as a screening method in residual analysis of veterinary drugs.     

Determination of seventeen pesticide residues in agricultural products by LC/MS

Residues of 17 pesticides in agricultural products were determined by LC/MS with an atmospheric pressure chemical ionization (APCI) interface in both positive and negative ion modes. Pesticides were extracted with acetonitrile, and the extracts were cleaned-up with a primary and secondary amine (PSA) mini-column eluted with acetone-hexane (1:1). Rice, orange and potato were spiked with the 17 pesticides at 0.1 microgram/g and analyzed by the proposed method. The average recoveries of these pesticides usually ranged from 70 to 98% and the relative standard deviations were usually around 10%. These results suggested that LC/MS with APCI could be used to determine the residue levels of the 17 pesticides in these crops.     

Studying the Effect of Household-Type Treatment and Processing on the Residues of Ethion and Profenofos Pesticides and on the Contents of Capsaicinoids in Green Chili Pepper Using GC-MS/MS and HPLC

The first aim of this study was to create, test, and apply a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, based on acetonitrile extraction, for simultaneous determination of pesticide residues in green chili pepper (fresh and dried forms). There is a group of 86 repeatedly detected pesticides in the agricultural food commodity in Al-Qassim region, Saudi Arabia. The suggested method is utilizing GC-MS/MS for simultaneous determination of those 86 pesticides. The limit of quantitation (LOQ) for each pesticide was set as the lowest fortification level that achieved acceptable recoveries in the range 70–120% with precision (RSD ≤ 20%). The results indicated that two organophosphorus pesticides, ethion and profenofos, in the analyzed chili pepper samples have significantly exceeded the European maximum residual limit (MRL) for pesticides. The second purpose of the study was to evaluate the effect of some different household-type treatment and processing procedures on the detected pesticide residues and on capsaicinoids (particularly, capsaicin and dihydrocapsaicin) which are responsible for the pungency of chili pepper, using GC-MS/MS and HPLC. Some recommendations were concluded for the best practices.     

高效液相色谱- 质谱法测定牛奶中6 种氨基甲酸酯农药残留

为建立同时测定牛奶中6 种氨基甲酸酯类农药残留量的方法,样品经乙腈提取,Oasis HLB 固相萃取柱净化后,采用高效液相色谱- 离子阱质谱(HPLC-ESI-MS/MS)进行测定,测定条件为：C18 色谱柱分离,甲醇-0.02mol/L醋酸铵溶液梯度洗脱,多反应监测模式检测。结果表明,6 种杀虫剂的定量限为1.0～10.0μg/kg,平均添加回收率为79.21%～91.38%,相对标准偏差为3.44%～5.71%。本实验所建立的6 种杀虫剂的测定方法完全可以满足当前农药残留分析的要求。     

Multiresidue analysis of pesticides in agricultural products by GC/MS,GC-ECD and GC-FTD using acetonitrile extraction and clean-up with mini-columns

An analytical method was developed for determination of organochlorine, pyrethroid and nitrogen-containing pesticide residues in agricultural products by GC/MS, GC-ECD and GC-FTD. Pesticides were extracted with acetonitrile, and the organic layer was cleaned up on C18 and ENVI-Carb/LC-NH2 cartridges. Pesticides were determined by GC/MS, GC-ECD and GC-FTD. Detection limits of pesticides by GC/MS and GC were below 1-30 ng/g and 1-3 ng/g, respectively. Recoveries of 27 out of 53 pesticides determined by GC/MS and 47 out of 53 determined by GC were 70-120%. This method was useful for the multiresidue analysis of pesticides in agricultural products. Pesticide residues in 81 domestic crops were investigated from April 2001 to March 2002. Residues of 31 pesticides were detected from 21 crops.     

Simultaneous determination of N-methylcarbamate and urea pesticides in agricultural products by LC/MS

A simultaneous determination method of 7 N-methylcarbamate and 7 urea pesticides in agricultural products by liquid chromatography/mass spectrometry (LC/MS) has been developed. Under reversed-phase liquid chromatographic conditions, 14 pesticides were analyzed using electrospray ionization (ESI) with simultaneous acquisition of positive ions and negative ions. Fourteen pesticides were extracted with acetone, 10% NaCl solution was added, and the pesticides were re-extracted with dichloromethane. The extract was concentrated under reduced pressure, and dissolved in methanol. The detection limits of 14 pesticides ranged from 0.0012 to 0.0056 microgram/g. The recoveries of pesticides were from 36.5 to 112.5% [RSD (n = 3) ranged from 0.5 to 48.1%] for 4 agricultural products.     

固相萃取一在线凝胶渗透色谱一气相色谱质谱联用测定蔬菜干制品中的18种有机磷和拟除虫菊酯残留

建立了蔬菜干制品中18种有机磷农药和拟除虫菊酯农药残留的在线凝胶渗透色谱一气相色谱／质谱（GPC-GC／MS）分析方法。样品以乙腈为提取剂超声波高速匀浆提取,提取液经ENVI．Carb固相萃取柱净化,除去样品中大部分的色素等干扰基质,再经在线GPC进一步净化除去大分子干扰物质,有效降低了样品基质带来的背景干扰。采用外标法定量,在质量浓度为0．02mg／kg,-0．5mg／kg有良好的线性关系,加标水平为0．4mg／kg时,18种农药的回收率基本都在80％-130％,相对标准偏差小于10％,检出限为0．001mg／kg-0．026mg／kg。经实验证明,该方法是一种快速,准确,灵敏度高的同时检测梅菜干中多种农药残留的检测方法。     

Determination of sucralose in foods by liquid chromatography/tandem mass spectrometry

A simple method for the determination of sucralose in various foods using liquid chromatography-electrospray ionization tandem mass spectrometry (LC/MS/MS) was developed. Sucralose was extracted with water or methanol, and the extract was cleaned up on a C18 cartridge, and diluted with water for injection into the LC/MS/MS. The LC separation was performed with a reversed-phase gradient on an ODS column, and the mass spectral acquisition was done in the negative ion mode by applying selected reaction monitoring (SRM). The recoveries of sucralose from various kinds of foods fortified at 100 micrograms/g and 5 micrograms/g were 88.1-96.7% and 92.7-98.5%, respectively. The lower limits of quantification were 0.5 microgram/g in beverage, low-malt beer, yogurt and chocolate and 2.5 micrograms/g in other foods. Forty-three commercial foods containing sucralose were analyzed by this method. Sucralose was detected in all samples at levels of 3.8-481 micrograms/g.