微波消解-电感耦合等离子体发射光谱法测定茶叶中的镉

Determination of Cadmium in Tea Using Microwave Digestion and Inductively Coupled Plasma Atomic Emission Spectroscopy

采用微波消解前处理技术,结合电感耦合等离子体发射光谱法对茶叶中镉元素含量进行测定,并以该方法对随机抽取的绿茶、乌龙茶、茉莉花茶和普洱茶各10个茶样中的镉元素含量进行分析。结果表明:镉标准物质质量浓度在0～100μg/L范围内,线性良好,相关系数R为0.9998,仪器检出限为1.88μg/L;茶样添加标准物质的回收率在95.7%～102.3%之间,茶样中镉元素含量6次重复测定的相对标准偏差为1.1%,方法回收率与精密度都较好,适合茶样中镉的快速测定;随机抽取的40个茶样的镉含量在0.017～0.138mg/kg之间,平均值为0.082mg/kg±0.028mg/kg,其中被检测的绿茶镉含量为0.060mg/kg±0.014mg/kg,乌龙茶为0.098mg/kg±0.027mg/kg,茉莉花茶为0.082mg/kg±0.032mg/kg,普洱茶为0.090mg/kg±0.023mg/kg。绿茶与其余3类茶镉含量的平均值差异显著(P<0.05)。

The contents of cadmium in tea samples including green tea,oolong tea,jasmine tea,and Pu,er tea were determined using microwave digestion followed by inductively coupled plasma atomic emission spectroscopy（ICP-AES）.The linear range was from 0 to 100μg/L（R2 = 0.9998）.The limit of detection（LOD） for cadmium was 1.88μg/L.The spike recovery was ranged from 95.7% to 102.3% with a relative standard derivation（RSD） of 1.1%.In conclusion,the method is a rapid,convenient,and highly sensitive method to determine cadmium content in tea samples.The contents of cadmium in randomly sampled forty tea samples were between 0.017 mg/kg and 0.138 mg/kg with an average of（0.082±0.028） mg/kg.The average content of cadmium in green tea showed a significant difference when compared with other tea samples（P0.05）.