茶叶中总汞含量测定的样品前处理研究

Sample pretreatment during determination of total mercury in tea

目的研究优化茶叶中总汞含量测定时的样品前处理。方法参照GB 5009.17-2014《食品安全国家标准食品中总汞及有机汞的测定》前处理过程,采用正交试验对影响微波消解的温度、时间和功率因素进行研究,获得较优的样品前处理参数,以此对盲审样品进行验证。结果测定茶叶中总汞含量时,可采用样品与硝酸直接加热方式进行预处理,微波消解过程对总汞回收率影响的因子由大到小为温度、功率和时间;最佳微波消解参数为温度80℃、时间8 min和功率1200 W,微波消解后的样品不需挥酸操作可直接定容测定;在最优前处理工艺参数条件下,盲审样品测定结果与其公布值基本一致。结论此样品前处理方式基本满足茶叶中中总汞含量测定的需求。

Objective To optimize pretreatment during determination of total mercury in tea.Methods According to GB 5009.17-2014 National food safety standard Determination of total mercury and organic mercury in food,the conditions of microwave digestion including temperature,time and power were optimized by the orthogonal experiment,then optimal parameters of sample pretreatment were obtained and were applied to validate the blind review sample.Result When determining total mercury content in tea,the processing of sample pretreatment was fit to directly heat with nitric acid.The temperature was the major influencing factor of microwave digestion,followed by power and time.Optimalized parameters of microwave digestion were as follows：temperature was 80 ℃,time was 8 min and power was 1200 W.The process of volatile acid could be concealed without the capacity after microwave digestion.Under the condition of the optimal pretreatment process parameters,the result of evaluation system of sample was satisfied with the proclamation value.Conclusion The method of sample pretreatment is appropriate for determination of total mercury in tea.