不同可可含量巧克力中咖啡因和可可碱的差异性分析

Difference Analysis of Caffeine and Theobromine in Chocolatewith Different Cocoa Content

本文建立了利用气相色谱-三重四极杆串联质谱(Gas Chromatography-Triple Quadrupole Tandem Mass Spectrometry,GC-MS/MS)同时测定不同巧克力中咖啡因和可可碱含量的分析方法。样品通过液氮冷萃后粉碎,再经甲醇超声提取30 min,采取多反应监测模式检测,内标标准曲线法定量。结果表明,可可碱和咖啡因在各自的线性范围内拥有良好的线性关系(r^(2)> 0.99),在低、中、高3个水平下加标回收率分别为77.90%~115.47%和86.69%~114.26%,相对标准偏差分别为1.43%~2.48%和1.30%~2.11%;对市售7种具有不同可可浓度的巧克力样品进行分析,检测可得样品中咖啡因及可可碱含量与其可可含量呈正相关。该方法适用于巧克力及可可类样品中的咖啡因和可可碱的同时快速定量分析。

In this paper,an analytical method was developed for the simultaneous determination of caffeine and theobromine in different chocolates using gas chromatography-triple quadrupole tandem mass spectrometry(GC-MS/MS).The sample was crushed after cold extraction with liquid nitrogen,and then subjected to methanol ultrasonic extraction for 30 minutes.Next,the samples were detected in multiple reaction monitoring mode and quantified by internal standard curve.The results indicate that theobromine and caffeine had a good linear relationship within their respective linear ranges(r^(2)>099),the average recovery rates in low,medium as well as high levels are 77.90%~115.47%和86.69%~114.26%respectively,with relative standard deviation(RSD)of 1.43%~2.48%and 1.30%~2.11%respectively;the content of caffeine and theobromine in 7 kinds of chocolate samples with different cocoa concentrations on the market were positively correlated with their cocoa content.This method is suitable for the simultaneous rapid quantitative analysis of caffeine and theobromine in chocolate and cocoa samples.