Department of Analytical Chemistry, Faculty of Chemistry, University of Alcalá, Alcalá de Henares (Madrid), Spain.
J Agric Food Chem. 2012 Feb 1;60(4):896-903. doi: 10.1021/jf202857y. Epub 2012 Jan 23.
A novel screening method using an automated flow injection electrospray ionization tandem mass spectrometry system is proposed for the simultaneous determination of five nonprotein amino acids (β-alanine, alloisoleucine, ornithine, citrulline, pyroglutamic acid) and three betaines (glycine betaine, trigonelline, proline betaine) after derivatization with butanolic HCl. MS/MS experiments were carried out in a triple-quadrupole instrument using multiple reaction monitoring mode in <2 min. The proposed method provided high fingerprinting power to identify the presence of five of the studied compounds in different types of vegetable oils (soybean, sunflower, corn, olive) with LODs at parts per billion levels. The method was validated, and different mixtures of extra virgin olive oil with seed oils were analyzed, achieving the typification for the detection of adulterations in extra virgin olive oils up to 2% w/w. The nonprotein amino acid ornithine was confirmed as a marker for adulteration in the olive oils analyzed.
提出了一种新的筛选方法，使用自动化流动注射电喷雾串联质谱系统，在衍生后可同时测定 5 种非蛋白氨基酸（β-丙氨酸、别异亮氨酸、鸟氨酸、瓜氨酸、焦谷氨酸）和 3 种甜菜碱（甘氨酸甜菜碱、三叶草碱、脯氨酸甜菜碱）。在三重四极杆仪器中进行 MS/MS 实验，采用多反应监测模式，<2 min 即可完成。该方法具有较高的指纹识别能力，可在不同类型的植物油（大豆、葵花籽油、玉米油、橄榄油）中检测到 5 种研究化合物的存在，LOD 达到十亿分之几的水平。该方法经过验证，并对特级初榨橄榄油与种子油的不同混合物进行了分析，实现了对特级初榨橄榄油掺假的检测，可达 2% w/w。在分析的橄榄油中，非蛋白氨基酸鸟氨酸被确认为掺假的标志物。
