Determination of Trace Mercury in Wastewater by a Flow Injection Analysis Composed of Immobilized Ionic Liquid Enrichment and Colorimetric Detection
ZHANG Jun, MAO Li-li, YANG Gui-peng*, GAO Xian-chi, TANG Xu-li
Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
Abstract：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%.
Key words：Room temperature ionic liquid;1-hexyl-3-methylimidazolium hexafluorophosphate;Inorganic mercury;Flow injection;Spectrophotometry;Enrichment
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