微波灰化-高效液相色谱-电感耦合等离子体质谱(ICP-MS)法测定茶叶中的铬酸铅

Determination of Lead Chromate in Tea by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry with Microwave Ashing

为了准确测定茶叶中铬酸铅的含量,为市场监管提供判断依据,茶叶样品经微波灰化仪在500℃的条件下灰化50 min后,用0.25 mol/L的NaOH和0.14 mol/L的Na_(2)CO_(3)混合碱性提取液在90~95℃下不间断搅拌提取10 min,提取液经色谱柱分离后,用电感耦合等离子体质谱(ICP-MS)法测定^(52)Cr,建立了微波灰化-高效液相色谱-电感耦合等离子体质谱仪测定茶叶中铬酸铅的方法。研究表明,方法在5.00~500μg/L线性良好,相关系数为0.9998,方法检出限低至2.5 mg/kg,三水平加标回收率为91.3%~95.3%,精密度在1.1%~2.0%。与电炉灼烧茶叶相比,微波灰化具有检出限低、精密度高、准确度良好等特性,能够满足茶叶中铬酸铅的测定。

To accurately determine the content of lead chromate in tea and provide a basis for market supervision,^(52)Cr was determined by ICP-MS before processed as follows:tea samples were ashing at 500℃for 50 minutes using a microwave ashing apparatus.Then,the ash was stirred extract with a mixed alkaline extract of 0.25 mol/L of NaOH and 0.14 mol/L of Na_(2)CO_(3) for 10 min at a temperature of 90-95℃.Subsequently,the extract was separated by a chromatographic column.A method for the determination of lead chromate in tea by microwave ashing-high performance liquid chromatography-inductively coupled plasma mass spectrometry was established.The results showed that the method had a good linearity in the range of 5.00-500μg/L,and the corresponding correlation coefficient was 0.9998.The detection limit of the method was as low as 2.5 mg/kg,the three-level spiked recovery were 91.3%—95.3%,and the precision were between 1.1%—2.0%.Compared with electric furnace burning tea,the microwave ashing has the characteristics of low detection limit,high precision,and good accuracy,which is suitable for the determination of lead chromate in tea.