Determination of Veterinary Drug Residues in Animal-derived Foods by Liquid Chromatography-Mass Spectrometry

[Objectives]This study was conducted to establish a rapid and effective method for simultaneous extraction of 54 kinds of veterinary drug residues in animal-derived food, including sulfonamides, quinolones, tetracyclines, malachite greens, penicillins, nitroimidazoles, tranquilizers and macrolides, by HPLC-MS. [Methods] The samples were extracted with 80% acetonitrile water(containing 0.1% formic acid), combined with QuEChERS extraction technology and C18 and PSA purification, analyzed by high performance liquid chromatography-mass spectrometry, and quantified by external standard method. The target substances were analyzed on ZORBAX Eclipse C18 chromatographic column using 0.2% formic acid water and 0.2% methanol as mobile phases. The gradient elution mode was used for chromatographic separation and multiple reaction detection. [Results] In the linear range of 0.5-50.0 ng/ml, the linear relationship of the 54 kinds of veterinary drug residues was good, with correlation coefficients(r~2) greater than 0.995, and the detection limits ranged from 0.30 to 1.00 μg/kg. The results showed that the recovery ranged from 75.4% to 118.2% when different matrixes were added for recovery. [Conclusions] This method is simple, efficient, accurate, stable, and highly operable. It is applicable to simultaneous batch screening of veterinary drug residues in animal-derived food, and has high practical application value.

CO₂Absorption Solvent Degradation Compound Identification Using Liquid Chromatography-Mass Spectrometry Quadrapole-Time of Flight (LCMSQTOF)

The degradation of the alkanolamine solvent used in the removal of acid gases from natural gas streams due to exposure to contaminants, thermal degradation and presence of oxygen or oxygen containing compounds will change the solvent properties, such as heat transfer coefficient, diffusion coefficient, and mass transfer coefficient of the solvent. Therefore, characterization and quantification of amine degradation product becomes one of the important analyses to determine alkanolamine solvent’s health. In order to identify degradation products of alkanolamine solvent, analytical strategies by using mass spectrometry (MS) as detector have been studied extensively. In this work, due to the low concentration of the amine degradation product, a method was developed for identification of alkanolamine degradation products using LCMS-QTOF technique. A strategy for identification of trace degradation products has been identified. Six (6) alkanolamine degradation products had been identified by using LCMS-QTOF targeted analysis in the blended alkanolamine solvent used in natural gas processing plant. Another fifteen (15) molecular formulas having similarity in chemical structure to alkanolamine degradation products were identified using untargeted analysis strategy, as possible compounds related to degradation products. Using LCMS-QTOF via targeted and untargeted analysis strategy, without tedious column separation and reference standard, enables laboratory to provide a quick and indicative information for alkanolamine solvent’s organic degradation compounds identification in CO2 adsorption, within reasonable analysis time.

HPLC及LC-MS测定榛子中氯吡苯脲和多菌灵残留

本文采用高效液相色谱法(HPLC)和液相色谱-质谱法(LC-MS)对干果榛子中氯吡苯脲和多菌灵残留量进行含量测定.HPLC和LC-MS均使用C18色谱柱,含量测定采取等度洗脱,流动相:甲醇-水(55∶45,体积比);体积流量:1.0 mL·min-1;测定波长:260 nm;柱温:30℃.LC-MS采取电喷雾离子源,梯度洗脱,体积流量:0.6 mL·min-1,柱温:30℃.结果表明,榛子中氯吡苯脲与多菌灵存在残留,氯吡苯脲质量浓度在1.00~10.00μg·mL-1范围内线性关系良好,加样回收率在95.58%~100.58%;多菌灵质量浓度在1.005~15.075μg·mL-1范围内具有良好的线性关系,加样回收率在95.61%~104.39%.实验证明,HPLC与LC-MS相结合的方法具有操作简便、灵敏度高、检出限低等优点,能有效地检测到榛子样品中膨大剂氯吡苯脲及杀菌剂多菌灵的残留,并确定其残留量,线性关系和回收率结果均令人满意.根据被检测的8批样品中氯吡苯脲和多菌灵两项农药残留量推断,作为一般干果食用榛子是安全的.

基于不确定度评估研究ID-LC-MS/MS法检测鸡蛋中氟虫腈砜残留量的关键控制点

为了控制检测结果准确性,以鸡蛋粉中氟虫腈砜残留分析标准物质[GBW(E)100779]为测试样,采用“自下而上”法对基于多功能净化柱(PAC柱)净化的同位素稀释液相色谱串联质谱(ID-LC-MS/MS)法进行测量不确定度评估。“鱼骨图”分析表明,不确定度分量主要来源有样品称样量、内标溶液添加体积、标准工作溶液浓度及其移取体积。内标溶液添加体积引入的不确定度最大,对检测结果不确定度的贡献率为68.59%;万分之一天平称量引入的不确定度可忽略不计。同位素内标的添加过程是ID-LC-MS/MS法检测的关键控制点,参考基准的合理选择和目标物的完全提取是准确测量的前提。进一步用LC-MS/MS法对参考物质、稀释剂和内标溶液的适用性进行了评估,并基于国家有证标准物质[GBW(E)100779]对提取方法进行了优化。研究结果有利于提升鸡蛋食品安全的检测质量和质控水平,为精准检测质控方案的设计提供新思路。

基于LC-MS/MS测定人体类固醇激素的研究进展

类固醇激素是一类具有环戊烷多氢菲结构的化合物,由细胞色素P450酶催化形成,在调节机体代谢、促进性器官发育等方面起着重要作用。临床上将类固醇激素水平作为肾上腺疾病、精神类疾病等的诊断指标。液相色谱-串联质谱(LC-MS/MS)联用技术因具有高灵敏度、高通量和高专属性的特点,已成为类固醇临床测定的首选方法。本文综述了LC-MS/MS在内源性类固醇激素测定中的应用,特别是在样品前处理、色谱条件和质谱条件优化等方面的研究进展,为临床上类固醇激素的诊断检测提供参考。

Chemical Components of Achyranthes bidentata Leaves by Ultra High Performance Liquid Chromatography-Mass Spectrometry

[Objectives] To study the chemical components and relative content of Achyranthes bidentata leaves and provide a scientific basis for further development and utilization of A. bidentata leaves.[Methods] The chemical components of A. bidentata leaves were rapidly analyzed using the ultra high performance liquid chromatography-time of flight-high resolution mass spectrometry (UHPLC-TOF-MS).[Results] Thirty eight chemical compounds were identified in samples of A. bidentata leaves collected from Wen County of Henan Province, in which seven chemical compounds had the relative content higher than 5%, linoleic acid reached 25.7% and inokosterone A reached 13.8%.[Conclusions] A. bidentata leaves contain many kinds of chemical compounds. This study is expected to provide a certain basis for further extraction of linoleic acid and inokosterone A.

A Validated Liquid Chromatography-Mass Spectrometry Method for the Detection and Quantification of Oxidative Metabolites of 2,2',4,4'-Tetrabromodiphenyl Ether in Rat Hepatic Microsomes

In the present study, we developed and validated an analytical method using ultra performance liquid chromatography-mass spectrometry (UPLC/MS) for the quantitative determination of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) metabolism by rat hepatic microsomes. BDE-47 is a brominated flame retardant that was widely used in a variety of consumer products and has subsequently been identified as a ubiquitous environmental contaminant. Hydroxy-bromodiphenyl ethers (OH-BDEs) were isolated from rat hepatic microsomes by liquid-liquid extraction. Chromatographic separation was achieved by UPLC on a C18 column with gradient elution using a mobile phase consisting of methanol and water, each containing 0.1% formic acid, at a flow rate of 0.2 mL/min. Detection and quantification were performed using a mass spectrometer in single ion recording mode with negative electrospray ionization. The UPLC/MS method was validated for linearity, limit of quantification (LOQ), accuracy, precision and recovery. The weighted calibration curves (1/X2) were linear over a concentration range of 5 - 250 nM with LOQ values between 5 nM and 50 nM for the individual OH-BDEs. Intra- and inter- day accuracy (%DEV) and precision (%RSD) values ranged from –11.7% to 9.5% and 5.9% to 16.5%, respectively. Recovery values of 70% to 90% were obtained for all OH-BDEs. The validated method allowed us to successfully analyze metabolite formation following incubation of BDE-47 with hepatic microsomes prepared from phenobarbital-treated rats. Results demonstrate that the UPLC/MS method has sufficient sensitivity and reproducibility to fully characterize the in vitro metabolism of BDE-47 and possibly other PBDEs.

Captiva EMR-Lipid技术结合UPLC-MS/MS快速测定牛羊产品中甲苯咪唑及其代谢物的残留量

建立了牛羊产品中甲苯咪唑及其代谢物羟基甲苯咪唑、氨基甲苯咪唑的通过式净化-超高效液相色谱-串联质谱测定的分析方法。样品经0.2%氨化乙腈溶液振荡提取,冷冻离心后,经Captiva EMR-Lipid小柱净化,直接进样分析。以安捷伦SB-C_(18)色谱柱(2.1 mm×100 mm,1.8μm)进行分离,以0.1%甲酸水和乙腈为流动相进行梯度洗脱,电喷雾正离子(ESI^(+))模式电离、多反应监测(MRM)模式进行检测,采用基质匹配标准工作曲线,内标法定量。结果表明,甲苯咪唑及其代谢物在0.2~50 ng/mL范围内线性良好,相关系数均大于0.999,甲苯咪唑及其代谢物的检出限(S/N>3)为0.3μg/kg,三水平的加标回收率在80.5%~108.0%之间,RSD为1.1%~5.8%。该方法操作简便、结果准确,克服了目前方法前处理繁琐、检测周期长等不足,适用于牛羊产品中甲苯咪唑及其代谢物残留量的快速检测。

Liquid Chromatography-mass Spectrometry Analysis on Effect of Roughage Types on Liver Metabolic in Dairy Cows

The major objective of this study was to determine the effect of corn straw or mixed diet on the small molecule metabolites of liver and milk production of healthy Chinese Holstein cows during lactation.In this study,metabolomic methods based on ultra performance liquid chromatography-mass spectrometry(LC-MS)were used to study the liver metabolites of dairy cows fed on corn straw diet or mixed diet.Ten healthy Chinese Holstein cows were randomly assigned to two groups,under the same management condition,fed different diets respectively,corn straw group(CS)or a mixture of alfalfa hay and Chinese wild rye hay mixed forage group(MF).All the cows were fed for 8 weeks and recorded body weight,dry matter intake,body condition score,fat,protein,lactose,milk yield and the total solids.Livers were sampled from each cow through a liver puncture needle for analysis of a significant difference in small molecule metabolites in cow liver samples from the two different diets.The results suggested that different diet types had significant effects on liver metabolism and milk components in dairy cows.The contents of milk fat,the total solids,milk protein,lactose,dry matter intake(DMI),milk yield,milk protein(%),lactose(%)and milk fat(%)of the corn straw group were significantly lower than those of the mixed forage group(p<0.05);the contents of phosphatidylcholine(PC),histidine,hypoxanthine and mridine in liver tissues of the corn straw group were significantly lower than those in the mixed forage group(p<0.05);acetylcarnitine,uric acid,triacylglycerol(TG),acetal phosphatidylcholine(plasmenyl-PC),acetalphosphatidylethanolamine(plasmenyl-PE)and sphingomyelin(SM)of the corn straw group were significantly higher than those in the mixed forage group(p<0.05).In summary,cows fed on mixed forage diet significantly improved milk yield and lactation performance clearly.

Novelties Filtration Theory of Liquid Chromatography-Mass Spectrometry in Volume Nanotube of Cotton Filament of Layers Woven Fabrics

Objectives of the research to present a modern theory of water purification for multiple purposes entitled “a novelties filtration theory of liquid chromatography-mass spectrometry” is an exceedingly sensitive and specific analytical technique in volume layers woven fabrics that can precisely determine the identities and quantities of compounds within volume Nanotube of cotton filament of layers woven fabrics. The problems are that the filters in the local and international markets have increased complications in configuration, installation and cost without reaching the efficiency that humanity hopes. Throw materials and methods the chromatography-mass spectrometry in layers woven fabrics, and throw the nanotube of cotton filament for purification of water dyes and smells. Industry, in which mass spectrometry is a convenient, versatile method for characterization and identification of process throw the Nanotube of cotton filament for purification of water dyes and smells. Results came up with a theme “innovations in textiles”, and also, for characterization of fibers and contaminants of the fabrics. Additive manufacturing in layers woven fabrics, are the processes used to synthesize a volume object under computer control with successive material layers that have been used and highlighted. The conclusions has included chromatography-mass spectrometry drop, physico-chemical, biological, combined physical-biological and chemical-biological treatment processes recently being developed to meet Jet-filtration, the strict discharging limits set by ASTM standards. Some important aspects of both qualitative and quantitative data analysis have been described and the power of using mass profiles to enhance selectivity and sensitivity has been demonstrated.

QuEChERS-LC-MS/MS测定姜油树脂、姜精油中8种农药残留及膳食风险评估

本研究建立了QuEChERS-液相色谱-串联四极杆质谱(LC-MS/MS)法测定姜油树脂、姜精油样品中噻虫嗪、吡虫啉、噻虫胺等8种农药残留,通过方法优化,选择乙腈-水-正己烷体系提取样品,QuEChERS方法净化提取液,在电喷雾离子源正离子模式下电离,多反应监测(MRM)模式下测定,并采用基质匹配标准曲线内标法进行定量分析。结果表明,8种农药在1~32μg/L浓度范围内的线性关系良好,相关系数(R 2)均大于0.99,方法检出限和定量限分别为0.03~0.16、0.10~0.53 mg/kg;3种不同加标水平下的回收率均在70%~119%之间,相对标准偏差(RSD)均小于20%。采用该方法测定实际样品,其中,噻虫嗪、吡虫啉、噻虫胺阳性样本的检出率较高,分别为56%、58%、52%,残留量大于1 mg/kg的样本量占比分别为12%、16%、10%,最高残留量分别为2.16、1.92、2.01 mg/kg,其他5种农药的检出率均低于20%。基于实际样品中农药残留中位值评估干姜片、姜精油和姜油树脂中噻虫嗪、吡虫啉、噻虫胺的慢性膳食摄入风险,评估结果远小于100%,表明农药残留的慢性摄入风险较小。

基于LC-MS/MS的大米中香兰素含量测定分析

采用液相色谱-串联质谱法(Liquid Chromatography Tandem Mass Spectrometry,LC-MS/MS)对不同品种和产地的大米中香兰素含量进行了测定和分析。本实验通过比较9种大米的香兰素含量,分析品种和产地对香兰素含量的影响,并探究不同储存条件下香兰素含量的变化。结果表明,籼稻品种的香兰素含量普遍高于粳稻品种,不同产地大米的香兰素含量存在明显差异,且储存条件对香兰素含量的保持有一定影响。本研究为大米品质评估和储存管理提供了科学依据。

基于LC-MS/MS的头孢他啶-阿维巴坦钠的血药浓度测定研究

目的:建立基于液相色谱串联质谱法(liquid chromatography-tandem mass spectrometry,LC-MS/MS)的头孢他啶-阿维巴坦钠的血药浓度测定方法,为临床头孢他啶-阿维巴坦钠的安全、合理用药提供参考。方法:以ACQUITY UPLC BEH C18色谱柱(2.1 mm×50 mm,1.7μm)、10 mmol/L乙酸铵(A)-100%乙腈(B)流动相、0.3 mL/min流速、正负离子切换多反应监测模式等为条件,建立LC-MS/MS的头孢他啶-阿维巴坦钠的血药浓度测定方法,并检验该测定方法的专属性、精密度、准确度、回收率、稳定性。结果:头孢他啶和阿维巴坦的保留时间分别为0.89 min和0.46 min,血浆中内源性物质对头孢他啶和阿维巴坦的检测无过多干扰;头孢他啶的线性方程为y=537.989x+56.4496(r=0.9953),其在0.5~200μg/mL浓度范围内具有较好的线性表现;阿维巴坦的线性方程为y=1788.74x+25.2269(r=0.9980),其在0.05~25μg/mL浓度范围内具有较好的线性表现;高、中、低浓度的头孢他啶和阿维巴坦样品的批内、批间精密度均在15.00%以内,而其准确度则均在±15.00%之间;而该方法中头孢他啶和阿维巴坦的回收率均在80.00%以上;此外,在样品在室温下放置6 h、在进样盘中放置24 h、在4℃下放置24 h和反复冻融(-80℃→25℃)3次等情况下,高、中、低浓度的头孢他啶和阿维巴坦样品的测量偏差均在±15.00%之间。结论:该方法具有较好的专属性和较大的线性范围,并且精密度、准确度、稳定性均较好,可以为临床患者头孢他啶-阿维巴坦钠的个体化用药提供依据。

Determination of penehyclidine hydrochloride in beagle dog plasma by liquid chromatography-electrospray ionization mass spectrometry and the pharmacokinetic study

To develop a fast and sensitive liquid chromatography-mass spectrometry method for the determination of penehyclidine hydrochloride （PH） in beagle dog plasma. PH and diphenhydramine hydrochloride （internal standard, IS） were extracted with a solvent mixture of petroleum ether-ethyl ether （7：3）. Chromatographic separation was achieved on a reversed-phase Eclipse XDB-C18 column （4.6 mm × 150 mm, 5 um） using the eluent of methanol-water （5 mmol/L ammonium acetate） （90：10, v/v, pH 5.8） as mobile phase. The electrospray ionization source was set at the positive multiple reaction monitoring （MRM） mode. This method involved the use of the [M＋H]^＋ ions of PH and diphenhydramine hydrochloride at m/z 316.4- 128.2 and m/z 256.4-167.2. The calibration curve was linear in the range of 1-1000 ng/mL with a correlation coefficient of 0.9988. The lower limit of quantification was 0.05 ng/mL. The precision, accuracy and recovery of the method were acceptable. Following intravenous injection admires＇ tration at doses of 0.5, 1 and 5 mg/kg PH, the main pharmacokinetic parameters were as the followings, t1/2a 0.33 h, t1/2β 2.44 1% tmax 0.058 1% AUC and Cmax exhibited a linear increase along with the increase of dose. The two-compartment model fit the three dose groups. This method was sensitive, accurate and fast for the determination of concentration of PH in beagle dog plasma. It could be used in pharmacokinetic studies of PH.

Determination of brominated diphenyl ethers in atmospheric particulate matter using selective pressurized liquid extraction and gas chromatography–mass spectrometry with a negative chemical ionization

This study describes the development and validation of a sensitive and reliable method for determination of polybrominated diphenyl ethers（PBDEs）in atmospheric particulate matter using selective pressurized liquid extraction（SPLE）and gas chromatography–mass spectrometry with a negative chemical ionization（GC-NCI-MS）.Extraction and clean-up were performed using PLE with 2 g florisil and 3 g silica placed in the extraction cells.Under optimal conditions,14 PBDEs were extracted at 70℃ using hexane/dichloromethane（50：50,v/v）as solvent.Validation of SPLE returned excellent recoveries for most analytes,with relative standard deviations mostly below20%.Method detection limits ranged from 0.13 to15.38 ng·mL^-1 for the GC-MS analyses.The method was successfully applied to atmospheric particulate matter of Beijing,where analytes were detected in the range of182.79 to 468.99 pg·m^-3.

A liquid chromatography with tandem mass spectrometry method for quantitating total and unbound ceritinib in patient plasma and brain tumor

A rapid, sensitive, and robust reversed-phase liquid chromatography with tandem mass spectrometry method was developed and validated for the determination of total and unbound ceritinib, a secondgeneration ALK inhibitor, in patient plasma and brain tumor tissue samples. Sample preparation involved simple protein precipitation with acetonitrile. Chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C_(18) column using a 4-min gradient elution consisting of mobile phase A(0.1% formic acid in water) and mobile phase B(0.1% formic acid in acetonitrile), at a flow rate of 0.4 m L/min. Ceritinib and the internal standard([^(13)C_6]ceritinib) were monitored using multiple reaction monitoring mode under positive electrospray ionization. The lower limit of quantitation(LLOQ) was 1 n M of ceritinib in plasma. The calibration curve was linear over ceritinib concentration range of 1–2000 n M in plasma. The intra-and interday precision and accuracy were within the generally accepted criteria for bioanalytical method( o15%).The method was successfully applied to assess ceritinib brain tumor penetration, as assessed by the unbound drug brain concentration to unbound drug plasma concentration ratio, in patients with brain tumors.

Determination of urine catecholamines and metanephrines by reversed-phase liquid chromatography-tandem mass spectrometry

The measurement of urine catecholamine and metanephrine concentrations is important for biochemical screening and diagnosis of pheochromocytoma.The goal of this work was to develop a simple liquid chromatography-tandem mass spectrometry(LC-MS/MS)method for determining catecholamines and metanephrines in urine to replace an existing liquid chromatographic method using electrochemical detection.Urine samples were prepared using Oasis weak-cation-exchange cartridges.The eluate was analyzed on an Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column in 3 min.Adrenaline,noradrenaline,dopamine,metanephrine,normetanephrine,and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring(MRM).No evidence of ion suppression was observed.The assay was linear up to 5μmol/L for adrenaline,5μmol/L for noradrenaline,6.1μmol/L for dopamine,5.6μmol/L for metanephrine,and 34.6μmol/L for normetanephrine,with lower limits of quantification of 5,5,12,6 and 7nmol/L,respectively.The intra-day and inter-day precisions for all analytes ranged from 0.59%to 4.64%and1.98%to 4.80%,respectively.External quality assurance samples were assayed and showed excellent agreement with the target values.This simple method provides an improved assay for determining urine catecholamines and metanephrines.

Untargeted and targeted mass spectrometry reveal the effects of theanine on the central and peripheral metabolomics of chronic unpredictable mild stress-induced depression in juvenile rats

L-theanine has been shown to have a therapeutic effect on depression.However,whether L-theanine has an excellent preventive effect on depression in children and adolescents and what its mechanism is have not been well explained.Given the complexity of the pathogenesis of depression,this study investigated the preventive effect and mechanism of L-theanine on depression in juvenile rats by combining serum and hippocampal metabolomic strategies.Behavioral tests,hippocampal tissue sections,and serum and hippocampal biochemical indexes were studied,and the results confirmed the preventive effect of Ltheanine.Untargeted reversed-phase liquid chromatography-quadrupole-time-of-flight mass spectrometry and targeted hydrophilic interaction liquid chromatography-triple quadrupole mass spectrometry were developed to analyze the metabolism changes in the serum and hippocampus to screen for potential biomarkers related to L-theanine treatment.The results suggested that 28 abnormal metabolites in the serum and hippocampus that were considered as potential biomarkers returned to nearnormal levels after L-theanine administration.These biomarkers were involved in various metabolic pathways,mainly including amino acid metabolism and lipid metabolism.The levels of amino acids and neurotransmitters in the phenylalanine,tryptophan,and glutamic acid pathways were significantly reduced after L-theanine administration compared with chronic unpredictable mild stress-induced rats.In summary,L-theanine had a significant preventive effect on depression and achieved its preventive results on depression by regulating various aspects of the body,such as amino acids,lipids,and inflammation.This research systematically analyzed the mechanism of L-theanine in preventing depression and laid the foundation for applying L-theanine to prevent depression in children and adolescents.

Liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry for Simultaneous Determination of Metformin and Glimepiride in Beagle Dog Plasma and Bioequivalence Study

A sensitive and selective liquid chromatography-electrospray ionization tandem mass spectrometry（LC- ES1-MS/MS） was used for the simultaneous determination of metformin and glimepiride in beagle dog plasma with glipizide as internal standard（IS）. After simplified protein precipitation with methanol, both the analytes and IS were chromatographed on a Zorbax CN column via gradient elution with methanol（containing 5 mmol/L ammonium ace- tate） and 5 mmol/L aqueous ammonium acetate as the mobile phase. Detection was performed by multiple reaction monitoring（MRM） scanning via ESI source operated in positive ionization mode. Specificity, linearity, accuracy, pre- cision, recovery, matrix effect and stability were validated for metformin and glimepiride in beagle dog plasma. The calibration curves were linear in a concentration range of 10-10000 ng/mL for metformin and 4-4000 ng/mL for glimepiride with both correlation coefficients higher than 0.99. The recoveries obtained for the analytes and IS were all between 82.7% and 101.2%. The method exhibited excellent performance in terms of selectivity, robustness, short analytical time and simplicity of sample preparation. Finally, the proposed method was applied to a bioequivalence study of self-made bilayer tablet and commercial formulation containing 500 mg of metformin and 1 mg of glimepi- ride in beagle dogs.

Stable Isotope Dilution Analysis of Gibberellin Residues in Tomato Paste by Liquid Chromatography-Tandem Mass Spectrometry

An accurate and sensitive method for the simultaneous determination of gibberellic acid（GA3）, gibberellin A4（GA4） and gibberellin A7（GA7） residues in tomato paste was developed by coupling solid phase extraction to high performance liquid chromatography-tandem mass spectrometry（LC-MS/MS） with electrospray ionization based stable isotope dilution analysis（SIDA）. The isotope labeled internal standard can compensate for the losses during the extraction and cleanup steps and for discrimination due to ion suppression. After extraction from methanol, hydrophile lipophilic balance（HLB） solid phase extraction（SPE） column was tested for the capacity of the cleanup of the tomato paste in compared with C18 SPE column which is the common way to the detection of GAs, and the former gained better result. Spiked experiments were performed in the non-contaminated tomato pastes and the recoveries of GA3, GA4 and GA7 were 42.6%―75.0% in external standard method（ESM） and 91.1%―103.8% in internal standard method（ISM） respectively. The validities of this method were investigated and good analytical performance for the three GAs was obtained, including low limits of method detection（2 ng/g for GA3 and GA4, 0.3 ng/g for GA7）, excellent linear dynamic ranges（5―500 ng/g for GA3 and GA4, 1―100 ng/g for GA7） and good relative standard deviation ranges（4.8%―9.4% for the intra-day test and 3.5%―11.9% for the inter-day test）.