Reversible intermittent flow-injection determination of mercury in sediments and vinasses by cold vapor atomic absorption spectrometry

摘要

A reversible intermittent flow-injection procedure is proposed for the automated determination of mercury in sediments and vin asses by cold vapor atomic absorption spectrometry, CVAAS. Solutions of sample and stannous chloride ore carried by twoair streams and sequentially injected into the generator/separator chamber in a segmented asynchronous merging zone configuration. The intermittent flow in the forward direction carries the mercury vapor through the flow cell, and in the backwarddirection, it aspirates the remaining solution from the vessel to waste. We investigated composition and concentration of reagents, flow rates, commutation times, reactor configuration, and conditions for mercury release. The accuracy was checked bymercury determination in a certified sediment and spiked vinasses and river waters. The system handles about 100 samples per hour (0.50-5.00 μg L{sup}(-1)), consuming co. 2.5 mL of sample and 50 mg of SnCl{sub}2 per determination. Good recoveries(92-103%) were obtained with spiked samples. Results ore precise (RSD < 3% for 2.5 μg Hg L{sup}(-1), n = 12) and in agreement with values for certified reference material at 95% confidence level.