The Research of Tea Analysis in Mass Spectrometry
|School||Liaoning Normal University|
|Keywords||HPLC-ESI-MS-MS ICP-MS Oligomeric Proanthocyanidins Theaflavin Trace Elements|
In this paper, the chemical compositions of tea are studied.The compositions ofoligomeric proanthocyanidins in the tea are analyzed and the contents of oligomericproanthocyanidins and theaflavin in the tea are determined by high performance liquidchromatography-electrospray ionization tandem mass spectrometry(HPLC-ESI-MS-MS).Thecontents of trace elements in the tea are determined by inductively coupled plasma massspectrometry(ICP-MS).Using HPLC-ESI-MS-MS technique,the components of oligomeric proanthocyanidins inthe tea are qualitatively analyzed by full scan and selected ion monitoring mode.Theoligomeric proanthocyanidins and theaflavin in the tea are quantitatively determined byproduct ion scan and multiple reaction monitoring mode.The oligomeric proanthocyanidinsand theaflavin are extracted by ultrasonic method and the factors affecting the extraction rateof the oligomeric proanthocyanidins and theaflavin are made by single factor experiment andorthogonal test. The chromatographic conditions(such as mobile phase,elution procedures andcolumn temperature,etc.)and the mass spectrometry conditions(such as product ion andcollision energy,etc.)of the oligomeric proanthocyanidins and theaflavin are selected andoptimized.In the determination of oligomeric proanthocyanidins,the method of recovery rateis between91.4%to109.8%and the coefficient of variation is less than7.5%.In thedetermination of theaflavin,the method of recovery rate is between91.2%to102.5%and thecoefficient of variation is less than4.1%.The accuracy and precision of two methods are veryhigh.The oligomeric proanthocyanidins in the tea are qualitatively analyzed by applyingHPLC-ESI-MS-MS technology,three kinds of monomers,three kinds of dimers(two kinds ofnon-ester-type dimers and one dimeric monoester)and three kinds of trimers of oligomericproanthocyanidins in the tea are mainly tested.The quantitative analysis of oligomericproanthocyanidins in the tea shows that WuYiShan of Rock Tea of ShuiKuLingRouGui>FuJianTieGuanYin>YunNanTangZhiZhen>GuangDongBaXianGuoHai>TaiWan ofOriental Beauty in the content of Proanthocyanidin B2in oolongTea;JinJunMei>YinJunMei>ChiGan(TongJunMei)in the content of Proanthocyanidin B2inJunMei series of Black Tea.The quantitative analysis of theaflavin in tea shows thatWuYiShan of Rock Tea of XianRenYan ShuiXian>TaiWan of OrientalBeauty>GuangDongBaXianGuoHai>YunNanTangZhiZhen in the content of theaflavin inoolong Tea;ChiGan(TongJunMei)>YinJunMei>JinJunMei in the content of theaflavin inJunMei series of Black Tea.Thus, the proanthocyanidin B2and theaflavin in oolong tea andblack tea are inversely proportional to the content. The tea are pretreated by microwave digestion,the8kinds of trace elements in the tea aredetected by ICP-MS.The method of recovery rate is between91.6%to108.0%and thecoefficient of variation is less than7.6%.The quantitative analysis of trace elements in the teashows that the content of chromium and manganese of trace elements ofYunNanTangZhiZhen are highest in YunNan series of tea; the content of iron,zinc andmolybdenum of trace elements of YunNanDianHongGongFu are highest in YunNan series oftea.