中药安宫牛黄丸(0.3 g试样)中可溶性汞用人工胃液(200 mL)于37 ℃的恒温水浴中提取4 h,分取其滤液1 mL,用0.5 mol·L-1硫酸溶液定容至25 mL,用电化学-汞蒸气-原子荧光光谱法测定其含汞量。方法中采用断续流动进样法引入试样溶液,进样体积为0.5 mL,试样溶液经过自制的电化学流通池,在阴极发生还原反应生成汞蒸气。文中对电化学流通池的结构作了详细描述,采用的电解电流为1.5 A(或0.54 A·cm-2),所用载气及屏蔽气的流量均为500 mL·min-1。试验结果表明:在所选择的试验条件下无基体效应。方法的检出限(3S/N)为2.1 ng·L-1。在1 μg·L-1汞的浓度水平上连续测定11次作精密度试验,求得其相对标准偏差为1.9%。在此中药实样的基础上,分别加入40,50,60 μg·g-1汞标准溶液,按方法测定其汞的回收值,算得其回收率在96%~102%之间。

Soluble mercury in a TCM called “An Gong Niuhang Pills” was extracted from the sample with artificial gastric juice (200 mL) at 37 ℃ in a water bath for 4 h, filtered and 1 mL aliquot of the filtrate was diluted to 25 mL with 0.5 mol·L-1 H2SO4, and mercury in the solution was determined by ECCV-AFS. Intermittant flow-injection sample introduction at volumes of 0.5 mL was adopted. An electrochemical flow cell for generation of mercury vapor by electrolytic reduction at the cathode was fabricated and its construction was described. Electrolytic current of 1.5 A (or 0.54 A·cm-2) was used for the electrolysis. Flow rates for both the carrier gas and shielding gas were same as 500 mL·min-1. No matrix effect was observed in the proposed method. Detection limit (3S/N) of the method was found to be 2.1 ng·L-1. Value of RSD (n=11) found at concentration level of 1 μg·L-1 Hg was 1.9%. On the base on a substantial sample of the TCM, standard mercury solutions of 40, 50 and 60 μg·g-1 were added for testing recovery of the method, results obtained were in the range of 96% to 102%.