固载化离子液体富集-流动注射分光光度法测定废水中痕量汞

以表面浸渍固载有疏水性室温离子液体—1-己基-3-甲基咪唑六氟磷酸盐(1-hexyl-3-methylimidazolium hexafluorophosphate，C₆mim]PF₆)的Amberlite XAD-7大孔树脂为固相萃取微柱的吸附剂，建立了微柱在线富集和流动注射-分光光度法测定废水中痕量游离态汞的新方法。在酸性介质中和十六烷基三甲基溴化铵(CTMAB)存在下，Hg2+与双硫腙反应生成红色的中性配合物可被微柱有效地定量富集。在优化的实验条件下，方法的线性范围为0.35～50 μg·L-1 Hg2+，检出限为0.067 μg·L-1 Hg2+。进样体积为50 mL时，Hg2+的富集因数为25倍。对环境水质汞标准样品(GSBZ50016-90)和加标废水样品的测定，回收率在99%～103%。

Determination of Trace Mercury in Wastewater by a Flow Injection Analysis Composed of Immobilized Ionic Liquid Enrichment and Colorimetric Detection

Amberlite XAD-7 resin was modified by room temprature ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate，C₆mim]PF₆) coating through a maceration method, gaining a new sort of hydrophobic adsorbent for the solid phase extraction mini-column. Trace inorganic mercury in wastewater samples was preconcentrated and determined by flow injection on-line mini-column sampling coupled with spectrophotometric determination. In acid medium, dithizone was employed as chelator with cetyltrimethylammonium bromide (CTMAB) to form a red neutral mercury-dithizone complex, which could be extracted quantificationally by solid phase extraction technique on the mini-column.Under the optimized conditions, the linearity and the detection limit of the proposed method were found to be 0.35 to 50.0 μg·L-1 Hg2+ and 0.067 μg·L-1 Hg2+, respectively. The enrichment factor of 25 times could be achieved with a 50 mL sampling volume and the developed procedure was successfully applied for the determination of mercury in the certified reference material (GSBZ50016-90) and the spiked dock wastewater samples with the recovery of 99%-103%.