超高效液相色谱-质谱法测定乳粉中的双氰胺

Determination of Dicyandiamide in Milk Powders Using Ultra Performance Liquid Chromatography Tandem Mass Spectrometry

双氰胺作为乳粉中一种新出现的污染物,对人体特别是婴幼儿的健康有重要影响.本研究建立了快速、准确测定乳粉中双氰胺的超高效液相色谱-电喷雾电离质谱（UPLC-ESI/MS）分析方法.结果表明,采用含2％氨水的乙腈对乳粉样品进行萃取,同时选用UPLC BEH HILIC（150mm×2.1 mm,1.7μm）色谱柱为固定相,以10 mmol/L甲酸铵/甲酸缓冲液（pH 4.0）-乙腈为流动相,梯度洗脱,基质匹配标准曲线定量分析,可以对5～200 μg/L双氰胺样品进行快速准确测定.在ESI正离子模式下,采用选择离子监测方法进行测定时,乳粉中双氰胺的检出限为10 μg/kg.加标浓度在50,100和200 μg/kg样品的回收率分别为83.7％,89.1％和96.7％,相对标准偏差均小于2％.本方法快捷、准确、灵敏度高,可用于乳粉中双氰胺的快速准确测定.

Dicyandiamide, as a new contaminant in milk powders, can lead to harmful effects to human health, especially to infants and young children. A rapid and accurate method for the determination of dicyandiamide in milk powders using ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry （UPLC-ESI-MS/MS） was established. The milk powders samples were extracted by acetonitrile which contained 2% NH4OH solution （ V/V）, the separation was carried out using an UPLC BEH HILIC（150 mm × 2.1 mm, 1.7μm）column, 10 mmol/L ammonium formate/formic acid buffer （pH 4.0） and acetonitrile as the mobile phases, gradient elution. The dicyandiamide was detected by ESI~ under selected ion monitoring mode. The quantified concentration range was 5- 200μg/L using matrix-matched calibration curves. When applying this method to determine real milk powder samples, the detection limits was 10μg/kg. The recoveries were 83.7% , 89.1% and 96.7% respectively when spiked negative samples with 50, 100 and 200 μg/kg dicyandiamide, and the relative standard deviations were less than 2%. This method is rapid, accurate, highly sensitive and suitable for the determination of dicyandiamide in milk powders.