高效液相色谱-质谱联用测定婴幼儿配方奶粉中的左旋肉碱

Determination of L-Carnitine in Infant Formula Milk Powder by Highperformance Liquid Chromatography-Mass Spectrometry

建立了婴幼儿配方奶粉中左旋肉碱含量的高效液相色谱-质谱联用测定方法。采用C4色谱柱(4.6mm×250 mm,5μm)进行分离,以甲醇-水(10∶90)为流动相,柱温25℃,流速1.0 mL.min-1,进样量为10μL,柱后分流比为1∶3,质谱采用多离子反应监测(MRM)方式进行检测,正离子模式,定量离子为m/z 162.2→103.1。在优化条件下,样品在10 min内完成分析,左旋肉碱在0.40～10.0 mg.L-1范围内线性关系良好(r=0.999 3)。方法的加标回收率为87%～106%,检出限(S/N=3)和定量下限(S/N=10)分别为39.0、116.9 ng。该方法操作简便、灵敏度高、重复性好,可用于婴幼儿配方奶粉中左旋肉碱的测定。

A high-performance liquid chromatography -mass spectrometric method was developed for the determination of L-carnitine in infant formula milk powder. After pretreatment procedure, the sample was separated on a C4 （4.6 mm x 250 mm, 5 μm） column using methanol -water （10 ： 90） as mobile phase with a flow rate of 1.0 mL · min- 1, a column temperature of 25 ℃ and injection vol- ume of 10μL. The split ratio of post column was 1 ： 3. The target compound was detected under multiple reaction monitoring（MRM） mode with positive ion using m/z 162.2→103.1 as the quantita- tion ions. Each analysis was completed within 10 rain. A good linear calibration for L-carnitine was obtained in the range of 0. 40 -10.0 mg · L^-1 with a correlation coefficient of 0. 999 3. The spiked recoveries were in the range of 87% -106%. The limit of detection（S/N = 3 ） and limit of quantita- tion（S/N = 10） of L-carnitine were 39. 0 ng and 116. 9 ng, respectively. The proposed method was simple, sensitive and reproducible, and was suitable for the determination of L-carnitine in infant formula food.