建立基于石墨化多壁碳纳米管(G-MWCNTs)的改良QuEChERS法结合液质联用技术测定柑橘中氨苄青霉素(Ampicillin)的简便、快速、准确的检测方法.在优选的色谱及质谱条件下,首先考察不同提取溶剂对氨苄青霉素提取回收率的影响;然后考察4种吸附剂的用量对氨苄青霉素回收率的影响,并优化净化剂使用量.结果表明,氨苄青霉素在0.5～100 ng/mL浓度范围内线性关系良好,相关系数(R2)均大于0.999,基质效应(matrix effect,MEs)在9.0%～21.2%之间,低、中、高(2、40、200 μg/kg)3水平下的平均回收率为85.9%～102.4%,相对标准偏差(Relative Standard Deviation,RSD)为2.1%～5.8%,检测限(Limit of Detection,LOD)和定量限(Limit of Quantity,LOQ)分别为1.0 μg/kg和4.0 μg/kg.在降解动态试验中,氨苄青霉素在沃柑和脐橙中的降解半衰期分别为1.2 d和1.1 d.该方法简便、快速、灵敏、准确,可为柑橘的质量评价提供有效的检测方法.
Establishment of QuEChERS-LC/MS Method for Detection of Ampicillin in Citrus and Its Dynamic Determination of Residual Degradation
To establish a simple,rapid and accurate method for the determination of ampicillin in citrus by improved QuEChERS method based on graphitized multi-walled carbon nanotubes(G-MWCNTs)combined with liquid chromatography-mass spectrometry.Under the optimized separation and detection conditions,the effects of different extraction solvent on the ampicillin recoveries were investigated.Then,the four kinds of adsorbent dosages on the purification efficiency were evaluated in terms of ampicillin recoveries,and the dosage of purification agent was optimized.The results showed that the linear relationship was good for ampicillin in the range of 0.5～100 ng/mL,the correlation coefficient were all greater than 0.999,the calculated matrix effects(MEs)ware 9.0%～21.2%.Under three different spiked concentrations(2,40,200 μg/kg),the average recoveries were obtained in the ranges of 85.9%～102.4%.The relative standard deviation(RSD)ware 2.1%～5.8%.The limits of detection(LOD)and limits of quantitation(LOQ)were 1.0 μg/kg and 4.0 μg/kg,respectively.Degradation dynamics test of the results showed that the half-lives of ampicillin in Fuchuan Citrus and Fuchuan navel orange were 1.2 d and 1.1 d.This proposed method is simple,rapid,sensitive and accurate,and it could provide an effective detection method for the quality evaluation of citrus.
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