在线富集离子色谱-质谱联用法同时测定饲料添加剂中的16种有机酸

建立了在线富集方式结合离子色谱-质谱(IC-MS)快速分离分析16种有机酸的方法。离子色谱配备自制富集柱和分离柱对有机酸进行在线富集和分离；质谱采用大气压化学电离源负离子电离方式(APCI^-)，在选择离子监控(SIM)模式下对有机酸进行定性和定量分析。采用200 μL大体积进样，在线富集时间为3 min，以NaOH溶液作为淋洗液，梯度洗脱。结果表明，富集柱和分离柱对有机酸有很好的富集分离能力；16种有机酸在30 min内完全洗脱，并在一定浓度范围内线性关系良好；方法检出限(LODs)为0.01~0.22 mg/L；加标回收率为70.6%~110.8%，相对标准偏差(RSD)≤6.3%。该方法样品前处理简单，分离速度快，有机酸检测灵敏度高，适用于多种饲料添加剂样品中有机酸添加剂的检测。

Simultaneous determination of 16 organic acids in feed additives by on-line enrichment and ion chromatography-mass spectrometry

A novel analytical method for simultaneous determination of sixteen organic acids by on-line enrichment and ion chromatography-mass spectrometry (IC-MS) was developed. On-line enrichment and separation of the organic acids were performed by ion chromatography on a homemade enrichment column and a homemade separation column. The qualitative and quantitative analyses of the organic acids were performed by mass spectrometry in selected ion monitoring (SIM) mode on the basis of atmospheric pressure chemical ionization (APCI) source in negative mode. The sample of 200 μL was injected for the analysis, and the on-line enrichment time was 3 min. The sodium hydroxide solution was used as a gradient elution system. The two columns made it possible to have a low limit of detection due to the good enrichment and separation capability. The sixteen organic acids were separated completely within 30 min. All curves showed good linearity within the test concentration ranges. The limits of detection (LODs) were between 0.01 and 0.22 mg/L, and the average recoveries were between 70.6% and 110.8%. The relative standard deviations (RSDs) were less than 6.3%. The results indicate that this method is simple, rapid, sensitive and accurate for the determination of the organic acids in feed additives.