茉莉花茶中铅镉元素的含量测定

Determination of Lead and Cadmium in Jasmine Tea

本文比较了样品前处理微波消解法和干灰化法,优化了微波消解条件和石墨炉原子吸收光谱仪的各项技术参数,建立了同时测定茶叶中重金属Pb和Cd的新方法。测定12批茉莉花茶及茶渣中Pb、Cd两种重金属元素含量,计算了常规泡制条件下,该二元素的溶出率。结果表明：用微波消解-石墨炉原子吸收法测定Pb和Cd方法,铅、镉金属元素检出限分别为0.03μg/L和0.004μg/L,加标回收率在93.6%～97.2%之间。方法简便、可靠,能满足茉莉花茶中Pb、Cd分析检测的要求。检测的12批广西生产的茉莉花茶Pb含量均未超标,沸水泡制后Pb的溶出率为10.5%～18.6%,Cd的溶出率约为12.0%～34.7%。

A method of Graphite furnace-atomic absorption spectrophotometry for simultaneously determing Pb and Cd in tea was developed by comparision of microwave digestion and dry-ash for sample pretreatment and optimizing the operating condition and instrument parameters.12 jasmine tea produced in Guangxi province were determined.The results indicated the detection limits of Pb and Cd could be reached 0.03μg/L and 0.004μg/L respectively,the recoveries were between 93.6%-97.2%.The method is rapid,accurate and reliable.The Pb contents for all tea sample determined were qualifi ed.The Pb extractive rates after conventional infusion by boilling water were in an arrange of 10.46-18.6%,and Cd were in 12.0%-34.7%.