亚临界水萃取技术检测茶叶中铅、铬、镉、砷4种重金属元素残留量

Determination of lead, chromium, cadmium, arsenic in tea by subcritical water extraction technique

目的：建立以亚临界水萃取(subcritical water extraction, SCWE)及电感耦合等离子体质谱(inductively coupled plasma mass spectrometry, ICP-MS)检测茶叶中铅(Pb)、铬(Cr)、镉(Cd)、砷(As)4种重金属元素残留量的方法。方法待测茶叶样品在5 MPa、150℃的亚临界条件下经提取15 min后,用ICP-MS测定。结果各目标物在1~50 mg/kg 范围内线性关系良好,相关系数均大于0.999。对茶叶基质进行1.0、5.0和10.0 mg/kg 三个水平的加标回收实验,4种重金属元素的回收率为70.19%~113.25%,相对标准偏差 RSD<8.2%。结论本方法的灵敏度、准确度和精密度均符合重金属元素残留测定的技术要求,适用于茶叶中重金属元素残留的检测。

Objective To develop aninductively coupled plasma mass spectrometry (ICP-MS) method with subcritical water extraction (SCWE) for the determination of heavy metals residues in tea, such as Pb, Cr, Cd and As. Methods Under the extraction pressure of 5 MPa, the test tea sample was extracted with subcriti-cal water at the temperature of 150℃for l5 minutes and then was determined by ICP-MS. Results The cali-bration curves showed a good linearity in the range of 1~50 mg/kg with r≥0.999. The recoveries of 4 harmful elements spiked in the tea at three levels of 1.0, 5.0, 10.0 mg/kg were from 70.19%to 113.25%with the relative standard deviations (RSD) lower than 8.2%. Conclusion The sensitivity, accuracy and precision of the me-thod could meet the technical standard of heavy metals residues determination. The method can be applied to the determination of heavy metals residues in tea.