牛油果中化学成分的内部萃取电喷雾电离质谱检测

Direct and Rapid Analysis of Avocado Using Internal Extractive Electrospray Ionization Mass Spectrometry

采用内部萃取电喷雾电离质谱(iEESI-MS)技术,以甲醇作为萃取溶剂,无需样品预处理,在优化条件下分别对牛油果果肉和果皮中化学成分进行快速直接鉴定,并考察了不同成熟度牛油果果肉中化学成分的差异.实验结果表明,在负离子检测模式下,从果肉中鉴定出棕榈酸、硬脂酸、棕榈油酸、油酸和亚麻酸等12种有效营养成分,从果皮中鉴定出儿茶素、绿原酸等11种营养成分.利用正交偏最小二乘判别分析法(OPLS-DA)对不同成熟度的牛油果果肉的iEESI-MS指纹谱图数据进行分析发现,此方法能够有效判别不同成熟程度的牛油果且5种化学成分差异显著.本方法无需样品预处理、样品耗量少、分析速度快(单个样品检测时间小于1 min)且操作简便,为植物有效营养成分和医用价值的开发提供了一种快速质谱分析新方法.

Avocado plays significant roles in food and medicine industries, due to its advantages of high nutrition profile, low sugar and high energy. In this work, the chemical compositions of pulp and peel of avocado were fast analyzed by internal extraction electrospray ionization mass spectrometry technology （iEESI-MS） without any pretreatment. Furthermore, Orthogonal partial least squares discriminant analysis （OPLS-DA） model was established to distinguish avocado＇ s maturity degree between unripening and ripening. The experimental results indicated that in negative ion mode, a total of 12 compounds such as palmitic acid, linolenic acid, palmitic acid, linolenic acid, oleic acid, stearic acid in pulp of avocado were indentified; while 11 compounds in peel of avocado were indentified including cianidanol, chlorogenic acid, pantothenic acid and so on. The differences of chemical compounds between unripening and ripening could be obviously observed through the model of OPLS-DA. The merits of this method to analyze compounds of avocado by iEESI-MS include simplicity, excellent specificity, high throughput and minimum sample pretreatment.