Department of Chemistry, Faculty of Science, Chulalongkorn University, Payathai Road, Bangkok 10330, Thailand.
Talanta. 2012 Sep 15;99:1040-5. doi: 10.1016/j.talanta.2012.05.055. Epub 2012 Jun 4.
A fully automated system for the determination of trace mercury in water by cold vapor atomic absorption spectrometry (CVAAS) is reported. The system uses preconcentration on a novel sorbent followed by liberation of the mercury and focusing by a gold trap. Mercury ions were extracted from water samples by passage through a solid phase sorbent column containing 2-(3-(2-aminoethylthio)propylthio)ethanamine modified silica gel. The captured mercury is released by thiourea and then elemental Hg is liberated by sodium borohydride. The vapor phase Hg is recaptured on a gold-plated tungsten filament. This is liberated as a sharp pulse (half-width<2 s) by directly electrically heating the tungsten filament in a dry argon stream. The mercury is measured by CVAAS; no moisture removal is needed. The effects of chloride and selected interfering ions were studied. The sample loading flow rate and argon flow rates for solution purging and filament sweeping were optimized. An overall 50-fold improvement in the limit of detection was observed relative to direct measurement by CVAAS. With a relatively modest multi-user instrument we attained a limit of detection of 35 ng L(-1) with 12% RSD at 0.20 μg L(-1) Hg level. The method was successfully applied to accurately determine sub-μg L(-1) level Hg in standard reference water samples.
本文报道了一种用于通过冷蒸气原子吸收光谱法（CVAAS）测定水中痕量汞的全自动系统。该系统使用新型吸附剂进行预浓缩，然后通过金阱释放和聚焦。汞离子通过含有 2-（3-（2-氨乙基硫代）丙基硫代）乙胺改性硅胶的固相吸附剂柱从水样中萃取出来。捕获的汞通过硫脲释放，然后通过硼氢化钠将元素汞释放出来。气相汞被镀金钨丝重新捕获。在干燥的氩气流中直接电加热钨丝，将其释放为尖锐的脉冲（半宽<2 s）。通过 CVAAS 测量汞；不需要去除水分。研究了氯化物和选定的干扰离子的影响。优化了溶液冲洗和灯丝吹扫的样品加载流速和氩气流速。与直接通过 CVAAS 测量相比，检测限提高了 50 倍。使用相对中等的多用户仪器，我们在 0.20 μg L(-1) Hg 水平下达到了 35 ng L(-1) 的检测限，相对标准偏差为 12%。该方法成功应用于准确测定标准参考水样中的亚微克级 Hg。
