称取经冷冻粉碎的橡胶样品0.2 g,用硝酸6 mL和过氧化氢2 mL在密闭的聚四氟乙烯(PTFE)消解罐中进行微波消解,所得溶液定容至50 mL。分取此溶液5.00 mL,加盐酸(5+95)溶液至10 mL,用氢化物发生-原子荧光光谱法测定此溶液中的汞含量。经试验选定分析条件:① 用0.5 g·L-1硼氢化钾溶液(溶于2 g·L-1氢氧化钠溶液中)作还原剂;② 以盐酸(5+95)溶液作载流;③ 光电倍增管负高压为260 V;④ 灯电流为15 mA;⑤ 原子化器高度为10 mm;⑥ 载气和屏蔽气流量依次为300,800 mL·min-1。方法的检出限(3s/k)为3 μg·L-1。用标准加入法做回收试验,测得平均回收率为95.7%,测定值的相对标准偏差(n=11)为4.3%。选取含汞高及低量的样品各1个,分别由10家实验室对所提出的方法做验证,结果较好。

The rubber sample was smashed with a frozen grinder, and a portion of 0.2 g of sample was taken and digested with 6 mL of HNO3 and 2 mL of H2O2 in a closed PTFE digester. The solution obtained was made up to 50 mL, and an aliquot of 5.00 mL after diluting to 10 mL with HCl(5+95) was used for HG-AFS determination of its Hg-content. Analytical conditions were optimized as follows: ① 0.5 g·L-1 solution of KBH4 dissolved in 2 g·L-1 NaOH solution was used as reductant; ② HCl(5+95) solution was used as carrier; ③ negative high voltage of photomultiplier: 260 V; ④ lamp current: 15 mA; ⑤ height of atomizer: 10 mm; ⑥ flow-rate of carrier gas and shielding gas: 300, 800 mL·min-1 respectively. Detection limit (3s/k) found was 3 μg·L-1. Value of average recovery found by standard addition method was 95.7%, with RSD (n=11) of 4.3%. Accuracy and precision of this method were further verified by an inter laboratory program among 10 laboratories, and satisfactory results were obtained.