高效液相色谱-电喷雾串联质谱法测定饲料中的N-氨基甲酰-L-谷氨酸

建立了高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)测定饲料中N-氨基甲酰-L-谷氨酸(NCG)含量的方法。饲料样品经甲醇提取、混合型强阴离子交换反相固相萃取(PXA)柱净化、HPLC分离后,采用ESI-MS/MS在正离子多反应监测(MRM)模式下进行检测,以碎片离子m/z 148.0和m/z 84.0进行定性,以碎片离子m/z 130.0进行定量。NCG的检出限(S/N3)为24μg/kg,定量限(S/N10)为80μg/kg,在20~1 000μg/L的质量浓度范围内峰面积与含量的线性关系良好,相关系数为0.999 9。对饲料中NCG在80、200、500 mg/kg等3个添加水平下的回收率进行了测定,分别为104.0%、103.5%、95.3%,相对标准偏差分别为7.5%、6.3%、5.8%。结果表明,该方法操作简单,净化效果好,快速,灵敏度和准确度高,符合对饲料样品中NCG检测分析的要求。

Determination of N-carbamyl-L-glutamic acid in feedstuff by high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

A method was developed for the determination of N-carbamyl-L-glutamic acid (NCG) in feedstuff by high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The feedstuff samples were extracted with methanol, cleaned-up by a ProElut mixed-mode of strong anion exchange inverse column (PXA). Then the samples were separated with HPLC and detected with MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI⁺). The fragment ions of m/z 148.0 and m/z 84.0 were used for qualitative analysis, and m/z 130.0 was selected for quantitative analysis. The limit of detection for NCG was 24 μg/kg (S/N >3), and the limit of quantification was 80 μg/kg (S/N >10). The standard calibration curve was linear over the range of 20-1000 μg/L, and the correlation coefficient was 0.9999. The recoveries of NCG in feedstuff were 104.0%, 103.5%, 95.3%, at the three spiked levels of 80, 200, 500 mg/kg with the relative standard deviations (RSDs) of 7.5%, 6.3% and 5.8%. The results showed that the method is simple, fast, highly sensitive, specific and with good purification effect. It can be applied to the analysis and determination of NCG in feedstuff.