ECCV-AFS Determination of Soluble Mercury in a Traditional Chinese Medicine

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%.