分散固相萃取结合液相色谱-串联质谱法测定饲料中8种脂溶性着色剂

建立了饲料中8种脂溶性着色剂(对位红、苏丹红Ⅰ、苏丹红Ⅱ、苏丹红Ⅲ、苏丹红Ⅳ、苏丹红7B、苏丹红G、苏丹黄)含量的液相色谱-串联质谱测定方法。饲料样品中脂溶性着色剂经乙腈提取,离心后上清液采用分散固相萃取净化,净化液稀释后进行LC-MS/MS分析。样品测定时采用Acquity BEH C18色谱柱进行色谱分离,以0.2%甲酸溶液-乙腈作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)模式检测,同位素稀释内标法定量。8种脂溶性着色剂在1.0~200μg/L范围内线性关系良好,相关系数(r~2)均大于0.998;在饲料中的方法检出限为5.0μg/kg,定量下限为10μg/kg。在10,50,500μg/kg加标浓度下8种脂溶性着色剂的回收率为102%~111%,批内相对标准偏差(RSD)为2.8%~8.0%,批间RSD为2.8%~7.8%。该方法能满足饲料样品中脂溶性着色剂监控的需要。

Determination of Eight Fat Soluble Colorants in Feed by Liquid Chromatography-Tandem Mass Spectrometry Combined with Dispersive Solid Phase Extraction

A method was developed for the simultaneous determination of eight fat soluble colorants (para red,sudan Ⅰ,Ⅱ,Ⅲ,Ⅳ,sudan red 7B,sudan red G and sudan yellow) in feed by liquid chromatography-tandem mass spectrometry(LC-MS/MS) combined with dispersive solid phase extraction.The samples were extracted with acetonitrile.Then the extract was purified by dispersive solid phase extraction method with N-propylethylenediamine (PSA) sorbent.After purification,the extract was diluted with 0.2％ formic acid solution.Before analysis by LC-MS/MS,the samples were separated on an Acquity BEH C18 column with a mixture of 0.2％ formic acid solution and acetonitrile as mobile phase under gradient elution conditions.The mass spectrometer was operated under multiple reaction monitoring(MRM) mode in the positive mode.The samples were quantified by the isotope dilution and the internal standard method.Good linearities were obtained for the eight fat soluble colorants in the concentration range of 1.0-200 μg/L with correlation coefficients more than 0.998.The recoveries of the analytes at fortified levels of 10-500 μg/kg were in the range of 102％ -111％.The limits of detection and the limit of quantitation for eight fat soluble colorants were 5.0 μg/kg and 10 μg/kg,respectively.The relative standard deviations of intra-assay were between 2.8％ and 8.0％.The relative standard deviations of inter-assay were between 2.8％ and 7.8％.The method is suitable for the determination of eight fat soluble colorants in feed.