Application of ion-exchange cartridge clean-up in food analysis III. Determination of benzylpenicillin, phenoxymethyl-penicillin, oxacillin, cloxacillin, nafcillin and dicloxacillin in bovine liver and kidney by liquid chromatography with ultraviolet detection

A multiresidue analytical method was developed for the simultaneous determination of benzylpenicillin (PCG), phenoxymethylpenicillin (PCV), oxacillin (MPIPC), cloxacillin (MCIPC), nafcillin (NFPC) and dicloxacillin (MDIPC) in bovine liver and kidney. The method involves the use of an ion-exchange cartridge for sample clean-up followed by ion-pair high-performance liquid chromatography with ultraviolet detection. The recoveries of PCG, PCV, MPIPC, MCIPC, NFPC and MDIPC from bovine liver spiked at levels of 0.5 mg/kg and 0.1 mg/kg were in the range of 73–91% and 83–96% with coefficients of variation of 1.4–4.2% and 3.4–8.7%, respectively. For bovine kidney spiked at levels of 0.5 mg/kg and 0.1 mg/kg, the recoveries of these compounds were 79–92% and 82–92% with RSDs of 1.8–5.9% and 2.7–7.8%, respectively. The detection limits for the six penicillins were 0.02–0.05 mg/kg in bovine liver and kidney.     

Application of ion-exchange cartridge clean-up in food analysis. VI. Determination of six penicillins in bovine tissues by liquid chromatography-electrospray ionization tandem mass spectrometry

A multiresidue analytical method was developed for the quantification of benzylpenicillin (PCG), phenoxymethylpenicillin (PCV), oxacillin (MPIPC), cloxacillin (MCIPC), nafcillin (NFPC) and dicloxacillin (MDIPC) in bovine tissues using liquid chromatography- electrospray ionization tandem mass spectrometry (LC-ESI MS/MS) with a multiple reaction monitoring technique. Using the deuterated PCG and NFPC as internal standard was effective for improvement of repeatability and accuracy. We chose [M-H-141]- as a monitor ion of MRM analysis and [M-H]- as a precursor ion for each penicillin. Combination of an ion-exchange cartridge clean-up and ion-pair LC enable us to determine the residual penicillins using the standard curves made from standard solutions without the influence of sample matrix on the MS. The average recoveries of PCG, PCV, MPIPC, MCIPC, NFPC and MDIPC from bovine liver, kidney and muscle at the same concentrations as the tolerance levels of PCG (50 microg/kg) ranged from 77 to 101% with the coefficients of variation ranging from 0.7 to 4.2% (n = 5). The limits of quantification for the six penicillins were 2-10 microg/kg in bovine muscle, liver and kidney (S/N ratio >10).     

Application of ion-exchange cartridge clean-up in food analysis IV. Confirmatory assay of benzylpenicillin, phenoxymethylpenicillin, oxacillin, cloxacillin, nafcillin and dicloxacillin, in bovine tissues by liquid chromatography-electrospray ionization tandem mass spectrometry

A multiresidue analytical method was developed for the confirmation of benzylpenicillin (PCG), phenoxymethylpenicillin (PCV), oxacillin (MPIPC), cloxacillin (MCIPC), nafcillin (NFPC) and dicloxacillin (MDIPC) in bovine tissues using electrospray ionization liquid chromatography-tandem mass spectrometry (LC-ESI-MS-MS) with a product ion scan mode. All penicillins gave [M-H]-, [M-H-CO2]- and [M-H-141]- as the product ion, when [M-H]- was selected as the precursor ion. Combination of an ion-exchange cartridge clean-up and the LC-ESI-MS-MS method can reliably identify all of these penicillins fortified at a concentration of 0.05 mg/kg in bovine tissues, including liver, kidney and muscle. The limits of confirmation satisfy the maximum residue limits for each of the penicillins established by the World Health Organization, US Food and Drug Administration, European Union and Japan.     

Studies on residual antibacterials in foods. IV. Simultaneous determination of penicillin G, penicillin V and ampicillin in milk by high-performance liquid chromatography

A rapid and simple method for the simultaneous determination of penicillin G (PCG), penicillin V (PCV) and ampicillin (ABPC) in milk is described. The retention behaviour of these beta-lactam antibiotics in reversed-phase liquid chromatography with mobile phases containing sodium alkylsulphonate was studied. Good separations were obtained with methanol-water-0.2 M phosphate buffer (pH 4.0) (5:13:2) containing 11 mM sodium 1-heptanesulphonate and a LiChrosorb RP-18 column. The sample was pre-treated with a Sep-Pak C18 cartridge. The peaks corresponding to each beta-lactam antibiotics can be confirmed with the treatment using penicillinase. The recoveries from milk fortified with sodium PCG, potassium PCV and ABCP at levels of 0.5 and 0.1 micrograms/g each were generally better than 87% and the relative standard deviations were 1.17-4.98%. The detection limits corresponded to 0.03 microgram/g of these beta-lactam antibiotics in milk.     

柱前衍生-高效液相色谱-荧光检测法测定罐头食品中的尿素

建立了罐头食品中尿素残留检测的柱前衍生-高效液相色谱-荧光检测方法.取5.0 g样品,经20 mL 1%(v/v)乙酸溶液提取、定容,离心后取上清液过滤,吸取0.5 mL提取液用呫吨醇进行衍生,采用高效液相色谱-荧光检测器进行测定.尿素在0.1~500 mg/L内线性良好,相关系数大于0.9995.实验表明,在5种罐头食品中各添加0.001~30 g/kg尿素,其平均回收率为80.2%~109.7%,相对标准偏差(n=6)为2.05%~6.53%,检出限为0.5 mg/kg,定量限为1.0 mg/kg.利用本研究建立的方法对168个实际样品进行测定,在3个肉类罐头样品中检出尿素,含量分别为10.6、62.1和2.6 mg/kg.方法稳定、可靠、操作简单,适用于罐头食品中尿素的检测.     

Determination of glyphosate and its metabolite, (aminomethyl)phosphonic acid, in serum using capillary electrophoresis.

Capillary electrophoresis has been used to separate and quantitate glyphosate and its major metabolite, (aminomethyl)phosphonic acid (AMPA), in serum. The two compounds, after derivatization with p-toluenesulphonyl chloride, were clearly separated with 0.1 M boric acid-sodium hydroxide buffer (pH 9.6) containing 10% methanol. The separation was completed within 15 min at an applied potential of 30 kV. Calibration curves for the assay were linear over both the lower (0.5-10 micrograms/ml) and the higher (10-100 micrograms/ml) concentration ranges. The within-run and day-to-day coefficients of variation of peak area were 1.4-4.4 and 4.4-8.5%, respectively, for glyphosate and 1.8-2.9 and 1.8-2.9%, respectively, for AMPA. The within-run and day-to-day precisions of the migration time for both compounds were less than 1.8% and less than 2.5%, respectively. The detection limit of both derivatives was 0.1 microgram/ml in spiked sera, and the recoveries of glyphosate and AMPA were 87.9-88.8 and 78.4-86.9%, respectively. In this study, the reproducibility and the effect of pH changes on the electropherograms were especially examined.     

Determination of beta-agonists in liver and retina by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the determination of bromobuterol, cimaterol, clenbuterol, clenpenterol, hydroxymethylclenbuterol, isoxsuprine, mabuterol, ractopamine, ritrodrine, salbutamol, terbutaline, and tulobuterol residues in bovine liver and retina is reported. This procedure uses enzymatic digestion, liquid-liquid extraction, and cleanup on Oasis HLB solid-phase extraction cartridges, followed by determination of the residues by LC-tandem quadrupole MS using atmospheric pressure chemical ionization in the positive ion mode. Overall average recoveries ranged from 23 to 76% for liver and 34 to 77% for retina. The mean values for samples fortified at levels between 0.5-2.0 microg/kg (liver) and 5-20 microg/kg (retina) agreed within 98-118% of the spiked levels, with coefficients of variation ranging from 6 to 20%. The decision limits, CCalpha, ranged from 0.1 to 0.3 microg/kg for liver, 1-3 microg/kg for retina, and detection capabilities, CCbeta, from 0.2-0.5 microg/kg for liver and 2-5 microg/kg for retina.     

分散固相萃取-高效液相色谱-串联质谱法同时测定畜禽肉中63种兽药残留

建立了分散固相萃取-高效液相色谱-串联质谱(dispersive-SPE-HPLC-MS/MS)同时测定畜禽肉中 β-内酰胺类、喹诺酮类、磺胺类、磺胺类增效剂和抗寄生虫类共5类63种兽药残留的新方法。样品经0.1 mol/L Na₂EDTA溶液及含1% (体积分数)乙酸的乙腈溶液涡旋提取,提取液经C18分散固相萃取净化后,用Poroshell EC-C18色谱柱(100 mm×2.1 mm, 2.4 μm)分离,在电喷雾离子源正离子模式下以动态多反应监测(DMRM)方式采集数据并做定性筛查和定量分析。63种药物在相应的浓度范围内线性关系良好,相关系数均大于0.99;不同畜禽肉(猪肉、牛肉及鸡肉)在3个不同添加水平下的平均回收率为62.2%~112.0%,相对标准偏差(RSD)为3.1%~16.3%,检出限(LOD, S/N≥3)和定量限(LOQ, S/N≥10)分别为0.1~3.0 μg/kg和0.5~10.0 μg/kg。该方法简便快速、灵敏可靠,适用于畜禽产品中兽药多残留的同时快速定性筛查和定量分析。     

气相色谱-质谱联用法同时测定乳及乳制品中的三聚氰胺及肌酐

建立了同时测定乳制品中三聚氰胺及肌酐的气相色谱-质谱联用方法。样品经1%三氯乙酸溶液萃取,混合型阳离子交换固相萃取净化,提取液用氮气吹干后加入N,O-双(三甲基硅基)三氟乙酰胺-三甲基氯硅烷(BSTFA-TMCS)硅烷化试剂,于75 ℃下衍生60 min,最后采用选择离子模式下的气相色谱-质谱测定。三聚氰胺和肌酐的定量限分别为0.10 mg/kg和0.20 mg/kg;在0.1～50 mg/L范围内的线性相关系数均大于0.99。实际样品中,肌酐在10～100 mg/kg和三聚氰胺在0.1～5.0 mg/kg添加范围内的回收率分别为80.7%～116.8%和77.6%～107.5%,相对标准偏差分别小于9.4%和8.5%。该方法能有效除去干扰,灵敏度高,回收率较好,可用于乳制品中三聚氰胺和肌酐的同时测定。     

Quantification of veterinary antibiotics (sulfonamides and trimethoprim) in animal manure by liquid chromatography-mass spectrometry

A fast and cost effective method was developed to extract and quantify residues of veterinary antimicrobial agents (antibiotics) in animal manure by liquid-liquid extraction and liquid chromatography-mass spectrometry. The compounds investigated include six sulfonamides, one metabolite, and trimethoprim. The method was performed without sample clean up. Recoveries from spiked manure slurry samples (spike level = 1 mg/kg) were as follows: sulfaguanidine (52%), sulfadiazine (47%), sulfathiazole (64%), sulfamethazine (89%), its metabolite N4-acetyl-sulfamethazine (88%), sulfamethoxazole (84%), sulfadimethoxine (51%), and trimethoprim (64%). Relative standard deviations of the recoveries were less than 5% within the same day and less than 20% between days. The limit of quantification was below 0.1 mg/kg liquid manure slurry for all compounds and calibration curves obtained from extracts of spiked samples were linear up to a level of 5 mg/kg liquid manure, except for trimethoprim (0.01-0.5 mg/kg). Analysis of six grab samples taken in Switzerland from manure pits on farms where medicinal feed had been applied revealed total sulfonamide concentrations of up to 20 mg/kg liquid manure.     

不同类别食品中21种邻苯二甲酸酯的气相色谱-质谱测定及其分布情况研究

首次建立了同时测定不同类别食品中21种邻苯二甲酸酯的气相色谱-质谱(GC-MS)分析方法.对各种类别的食品采取不同的分离、净化方法;优化了成分复杂的香精或植物提取物等样品的色谱测定条件,通过提取特征离子进行检测和确证,消除了基质干扰,避免产生假阳性结果;探讨了邻苯二甲酸酯类的质谱碎裂机理.21种邻苯二甲酸酯的质量浓度在...     

液相色谱-串联质谱法检测食品中的多种易滥用着色剂

建立了硬糖、果酱、液态奶、果汁中酸性红52、红色2G、喹啉黄、专利蓝、酸性红26、柠檬黄、靛蓝、胭脂红、诱惑红、日落黄、亮蓝、苋菜红等12种易滥用着色剂残留量的液相色谱-串联质谱分析方法。样品用水溶液稀释提取,经聚酰胺固相萃取柱净化后,在Agilent XDB-C18色谱柱分离,以20 mmol/L乙酸铵溶液和乙腈为流动相进行梯度洗脱。质谱采用电喷雾负离子(ESI~)模式电离,多反应监测(MRM)模式检测,基质匹配标准溶液外标法定量。易滥用着色剂在0.5～50 mg/L范围内呈线性相关,相关系数(r)均大于0.99,其定量限(信噪比大于10)为0.5 mg/kg,检出限(信噪比大于3)为0.1 mg/kg。各种基质样品在0.5、5和50 mg/kg添加水平时,易滥用着色剂的回收率范围为62.6%～115.3%,相对标准偏差(RSDs)为2.6%～26.3%,可以满足食品中易滥用着色剂含量的检测需要。     

Sample preparation for residue determination of gentamicin and neomycin by liquid chromatography

The effect of sample preparation on the determination of gentamicin and neomycin residues in animal tissues was investigated. The extract was mixed with an ion-pair reagent and applied to an octadecyl cartridge. The cartridges were washed with buffer followed by water, and analytes were eluted with ion-pair buffer-acetonitrile mixture. The aminoglycosides were derivatized with 9-fluorenylmethyl chloroformate prior to liquid chromatography using a reversed-phase column and fluorescence detection. Under the conditions applied neomycin was fully separated from all the gentamicin compounds. The highest recoveries of gentamicin and neomycin from spiked tissues were obtained using trichloroacetic acid after initial extraction with phosphate-buffered saline. No interfering peaks from endogenous compounds of matrix were noted at the elution position of the analytes. An intra-laboratory validation of the whole procedure was performed. The calibration graphs were linear from 0.1 to 1.0 mg/kg for gentamicin, and from 0.2 to 1.0 mg/kg for neomycin. Limits of detection were 0.05 mg/kg and 0.10 mg/kg for gentamicin and neomycin, respectively. Limits of quantitation for gentamicin and neomycin were 0.1 and 0.20 mg/kg muscle, liver or kidney tissue, respectively. Recoveries of gentamicin spiked at levels of 0.1 mg/kg porcine tissues ranged from 76 to 86%. Recoveries of neomycin spiked at levels of 0.2 mg/kg porcine tissues ranged from 77 to 83%. The validated procedure was used to determine gentamicin concentrations in porcine tissue after dosing with gentamicin at a level of 5 mg/kg body mass.     

Analysis of DDT residues in soil by ELISA: an international interlaboratory study

An international interlaboratory study was conducted to determine the performance of a group of laboratories from developing and developed countries. The study used a commercial microwell ELISA on unknown samples spiked with different levels of DDT. The study design was based on Youden pairs and balanced replicates. Two soils, differing in particle size distributions, organic matter content, and cation-exchange capacities and thought to be DDT-free, were spiked at 5 DDT levels between 0.025 and 2 mg/kg. Nineteen laboratories in 17 countries took part in the collaborative trial; of these, the majority were modestly equipped laboratories in developing countries. Samples were analyzed without filtration or cleanup and using standards of pure DDT in methanol. Data were analyzed for repeatability and reproducibility, and average recoveries at the spike levels were calculated. Mean real recoveries for both soils were similar (103% for soil A and 100% for soil B), with values between 0.1 and 2 mg/kg DDT. Precision estimates were best in the linear working range of the assay (0.1-0.5 mg/kg DDT), with reproducibility relative standard deviations (RSDR) typically averaging about 38 and 46% near the upper and lower detection limits, respectively. Corresponding repeatability relative standard deviation (RSDr) values were 20-36% and 36-57%. Thus, even though much of the trial was performed under developing country conditions, performance statistics were similar to other reported results obtained with ELISAs on small molecules of agricultural importance, such as mycotoxins and pesticide and antibiotic residues.     

GC-MS同时测定油脂性的食品及食品添加剂中16种邻苯二甲酸酯类迁移物

采用气相色谱电子轰击离子源质谱(GC-EI-MS)技术同时分析油脂性食品及油脂性添加剂中16种邻苯二甲酸酯(PAEs)环境激素的迁移量。以GC-EI-MS选择离子检测模式(SIM)进行定性和定量分析,优化出了油脂性基质的系统前处理方法。当样品的加标浓度水平分别为0.25和0.50 mg/kg时,加标回收率为58.9%～111.1%,相对标准偏差为1.0%～4.6%。16种PAEs在0.1～2.0 mg/L浓度范围内16种PAEs都呈现良好的线性关系,r为0.9960～0.9995,检测限(LOD)均为0.07～0.70μg/kg。方法已用于8批油脂性的食品和7批油脂性食品添加剂中16种痕量PAEs迁移物的分析。     

Determining the procedure for routine residue monitoring of sulfamethazine in edible animal tissues.

A simplified method to determine/identify residual sulfamethazine (SMZ) in edible tissues from cattle, pigs, chickens and sheep by a high-performance liquid chromatography (HPLC) with a photo-diode array detector is presented. The sample preparation was performed by homogenizing with 30% (v/v) ethanol in water followed by an Ultrafree-MC/PL as a centrifugal ultra-filtration unit. For determination/identification of SMZ, a reversed-phase C(4) column and a mobile phase of 15% (v/v) ethanol in water with a photo-diode array detector was used. Average recoveries from spiked SMZ (0.1-1.0 mg kg(-1)) were >or=80% with coefficients of variation between 1.3 and 4.3%. The limits of quantitation were calculated to be 0.057-0.060 mg kg(-1). The total time and solvent required for the analysis of one sample were <40 min and <2 mL of ethanol, respectively.     

碳青霉烯类抗生素亲水作用色谱方法研究及其应用

建立了测定人尿液和自来水中4种碳青霉烯类抗生素(比阿培南、美罗培南、多利培南和厄他培南)的亲水作用色谱方法,所用流动相具有较好的质谱兼容性,可用于色谱-质谱联用。以XAmide为色谱柱,考察了乙腈比例、缓冲盐浓度和pH值对4种抗生素保留的影响,提出了可能的保留机理;所发展的方法对目标样品具有良好的线性响应:比阿培南、多利培南和厄他培南的线性范围为0.1~250 mg/L, R²=0.9999;美罗培南的线性范围为0.5~250 mg/L, R²=0.9998; 4种抗生素的定量限(LOQ)为0.1~0.5 mg/L。尿液样品和自来水样品在5 mg/L和25 mg/L两个水平的加标回收率分别为100.4%~111.9%和79.6%~107.4%,相对标准偏差(RSD)分别不大于1%和5%。该方法准确、灵敏、简便,可用于人尿液和自来水中多种碳青霉烯类抗生素的检测。     

固相萃取-气相色谱-质谱法测定食品中23种邻苯二甲酸酯

建立了同时检测食品中23种邻苯二甲酸酯类化合物的固相萃取-气相色谱-质谱(GC-MS)分析方法。样品经正己烷或乙腈提取、玻璃ProElut PSA固相萃取柱净化,GC-MS选择离子监测模式(SIM)测定。考察了不同种类食品的提取、净化方法。23种邻苯二甲酸酯的线性范围除邻苯二甲酸二异壬酯(DINP)和邻苯二甲酸二异癸酯(DIDP)为0.5～5 mg/L外,其余均为0.05～5 mg/L,相关系数(r)除DIDP外均大于0.99。方法的检出限(信噪比为3)为0.005～0.05 mg/kg,定量限(信噪比为10)为0.02～0.2 mg/kg。在10种食品基质中3个加标水平的平均回收率为77%～112%,相对标准偏差(RSD,n=6)为4.1%～12.5%。该方法稳定、可靠,操作简单,适用于食品中邻苯二甲酸酯类化合物的检测与确证。     

反相高效液相色谱法同时测定化妆品中7种萘二酚类物质

建立了反相高效液相色谱((RP-HPLC))同时测定化妆品中7种萘二酚类物质的分析方法。膏霜类、乳液类和水类样品用95%(v/v)乙醇提取,粉类样品用95%乙醇-0.1%乙酸(3:2, v/v)溶液提取,经离心、过滤后,用C18柱,以甲醇-0.1%乙酸溶液为流动相梯度洗脱分离,使用二极管阵列检测器检测,以保留时间定性,并以紫外吸收光谱图辅助定性,外标法定量。结果表明,萘二酚类物质在线性范围内线性关系良好,相关系数均不低于0.999 0,方法的定量限(以信噪比为10计)为0.5～1.2 mg/kg,添加水平为5.0～50 mg/kg时回收率为84.0%～102%,相对标准偏差(n=6)为1.3%～5.7%。该法前处理简单、回收率高、精密度好,适用于非蜡基类化妆品中萘二酚类物质的测定。     

高分辨快速液相色谱-串联质谱法测定肉制品中的刚果红

建立了肉制品中刚果红的高分辨快速液相色谱-串联质谱(RRLC-MS/MS)测定方法。均质后的样品经乙腈与正己烷混合溶剂(1∶1)提取,乙腈提取层离心后直接上机测试。使用Agilent XDB C18色谱柱,以乙腈和10 mmol/L甲酸铵水溶液为流动相梯度洗脱,采用多反应监测方式(MRM)负离子模式检测,定量离子对与定性离子对分别为m/z 325.0/416.0与m/z 651.0/152.0,外标法定量。结果表明,刚果红在0.1～10mg/L范围内线性关系良好(r2>0.999),加标回收率为91%～102%,RSD为1.2%～4.0%,检出限与定量下限分别为0.07 mg/kg和0.18 mg/kg。该方法准确、高效,可用于肉制品中刚果红染料的快速检测。