碱消解-HPLC同时测定土壤中的无机汞和甲基汞

Simultaneous Determination of Inorganic Mercury(Ⅱ) and Methyl Mercury in Soil by Alkaline Digestion-High Performance Liquid Chromatography

建立了碱消解-高效液相色谱(HPLC)同时测定土壤中无机汞和甲基汞的分析方法。试验研究了KOH/甲醇提取液浓度、消解时间以及反萃取剂Na2S2O3浓度对碱消解过程中甲基汞提取率的影响,当KOH/甲醇提取液浓度为25%、消解时间为12 min、Na2S2O3浓度为0.01 mol/L时,KOH/甲醇溶液对土壤甲基汞的提取率最高。提取出的无机汞和甲基汞,经衍生后HPLC法测定,流动相最佳选择为0.01 mol/LTBABr和0.025 mol/L NaCl的水溶液:甲醇=45:55(v:v)。在优化检测条件下,土壤样品中无机汞和甲基汞的检出限分别为1 ng/g和10 ng/g。该方法样品前处理简单、线性范围宽、精密度高、准确性好,适用于土壤中汞化合物的形态分析。

A method for the determination of inorganic mercury and methyl mercury in soils by high performance liquid chromatography （HPLC）with alkaline digestion was established. Experiments were done for examining the effects of KOH/ methanol concentration, digestion time and Na2S2O3 concentration on the extraction rates of methyl mercury in the process of alkaline digestion. When KOH/methanol concentration was 25%, digestion time was 12 min and Na2S2O3 concentration was 0.01 mol/L, the highest extraction rate of methyl mercury in soils were obtained. After extracted with KOH/methanol, mercury and methyl mercury were derivated and then detected by HPLC. The mobile phase was methanol＋water （55＋45 by volume）containing 0.01 mol/L tetra-n-alkylammonium bromides and 0.025 mol/L sodium chloride. In the optimized conditions, the detection limits for inorganic mercury and methyl mercury were 1 ng/g and 10 ng/g respectively. The method with a simple pre-treatment procedure, broad linear range, good accuracy and precision is suitable for the determination of mercury speciation in soils.