LC-MS/MS 与酶法测定婴幼儿配方食品及乳制品中总胆碱和总肉碱的比较

Comparison of LC-MS/MS and Enzymatic Methods for the Determination of Total Choline and Total Carnitine in Infant Formula and Milk Products.

机构信息

Fonterra Co-operative Group Ltd, P.O. Box 7, Waitoa 3380, New Zealand.

Hill Laboratories, Private Bag 3205, Hamilton 3240, New Zealand.

出版信息

J AOAC Int. 2020 Sep 1;103(5):1293-1300. doi: 10.1093/jaoacint/qsaa060.

DOI:10.1093/jaoacint/qsaa060

PMID:33241401

Abstract

BACKGROUND

Choline and l-carnitine are classified as pseudo-vitamins because of their conditionally essential status. As they are involved in multiple physiological metabolic pathways in the human body, they are routinely fortified in infant and adult nutritional formulas.

OBJECTIVE

The performance of an LC-MS/MS method for the analysis of choline and carnitine, compared with enzymatic methods in routine use for the analysis of total carnitine and total choline, is described.

METHOD

Powder samples were reconstituted, with release of carnitine and choline facilitated by both acid and alkaline hydrolysis and the extract analyzed by LC-MS/MS. Quantitation was by internal standard technique using deuterium-labeled carnitine and deuterium-labeled choline.

RESULTS

Method range, specificity, sensitivity, precision, recovery, accuracy, and ruggedness were assessed for milk powders, infant formulas, and soy- and milk-based nutritional products. Spike recoveries of 94.0-108.4% were obtained for both total carnitine and choline, and no statistical bias (α = 0.05) between measured results and certified values (choline: P = 0.36; free carnitine: P = 0.67) was found for NIST 1849a certified reference material (NIST1849a). Precision, as repeatability relative standard deviation (RSD), was 2.0% RSDr for total carnitine and 1.7% RSDr for total choline. Equivalent results for total choline and total carnitine were obtained by LC-MS/MS and enzymatic methods (n = 30).

CONCLUSIONS

The described LC-MS/MS method is fit for purpose for routine product compliance release testing environments. This validation study has confirmed that alternative enzymatic assays can be used with confidence in laboratories in which LC-MS/MS platforms are unavailable.

HIGHLIGHTS

An LC-MS/MS method was evaluated and found to be fit-for-purpose for routine product compliance release testing of infant formula. The LC-MS/MS method was compared with enzymatic methods for the analysis of total carnitine and total choline. Alternative enzymatic assays can be used with confidence in laboratories in which LC-MS/MS platforms are unavailable.

摘要

背景

胆碱和左旋肉碱被归类为条件必需维生素，因为它们在人体中参与多种生理代谢途径，因此它们通常被添加到婴儿和成人营养配方中。

目的

描述一种 LC-MS/MS 方法分析胆碱和肉碱的性能，与常规用于分析总肉碱和总胆碱的酶法进行比较。

方法

粉末样品经酸、碱水解释放肉碱和胆碱，提取液用 LC-MS/MS 分析。采用氘标记肉碱和氘标记胆碱的内标技术进行定量。

结果

对奶粉、婴儿配方食品以及大豆和牛奶为基础的营养产品进行了方法范围、特异性、灵敏度、精密度、回收率、准确度和稳健性评估。总肉碱和胆碱的加标回收率分别为 94.0%-108.4%，NIST 1849a 认证参考物质（NIST1849a）的测定值与认证值之间无统计学偏差（胆碱：P=0.36；游离肉碱：P=0.67）（α=0.05）。LC-MS/MS 法和酶法测定总肉碱的重复性相对标准偏差（RSD）分别为 2.0%RSDr 和 1.7%RSDr。LC-MS/MS 法和酶法测定总胆碱的结果相当（n=30）。