树脂富集-电感耦合等离子体质谱法测定液化石油气中痕量汞

Determination of trace mercury in liquefied petroleum gas by inductively coupled plasma mass spectrometry after enrichment with resin

丙烷脱氢技术越来越受到重视,其生产原料液化石油气(LPG)中汞含量的控制是生产的关键环节,因此迫切需要一种高效稳定的检测汞的方法。应用阳离子交换树脂在线富集液化石油气中的汞,用20%(体积分数,下同)王水湿法消解,建立了电感耦合等离子体质谱法(ICP-MS)测定LPG中汞的方法。对富集条件和消解方式进行了优化。确定汞的在线富集条件为:压力1.3MPa,流速500mL/h;样品的消解程序为:12g样品中加入50mL 20%王水于60℃消解1h。以基体匹配标准溶液校正了基体效应,选用202 Hg为待测同位素消除了质谱干扰。实验表明,方法的线性范围为0.08~50μg/L,线性相关系数为0.999 795,检出限为0.02μg/L。采用实验方法对液化石油气实际样品中汞进行分析,结果的相对标准偏差(RSD,n=5)为1.3%~6.6%,加标回收率为95%~101%。

The propane dehydrogenation technology receives more and more attention.The control of mercury content in raw material liquefied petroleum gas（LPG）is the key step for the production.Therefore,it is imperative to develop a high-efficiency and stable method for the detection of mercury.Mercury in LPG was on-line enriched using cation exchange resin.After wet digestion with 20%（volume fraction,similarly hereinafter）aqua regia,the determination method of mercury in LPG by inductively coupled plasma mass spectrometry（ICP-MS）was established.The enrichment conditions and digestion methods were optimized.The on-line enrichment conditions for mercury were obtained as follows：pressure of1.3 MPa and flow rate of 500 mL/h.The digestion procedures of sample were found as below：50 mL of20% aqua regia was added into 12 g of sample followed by digestion at 60℃for 1 h.The matrix effect was corrected using the matrix matching standard solution.The MS interference was eliminated using 202 Hg as the isotope for determination.The results showed that the linear range of method was 0.08-50μg/L,the linear correlation coefficient was 0.999 795,and the detection limit was 0.02μg/L.The proposed method was applied for the analysis of mercury in actual LPG sample.The relative standard deviations（RSD,n=5）of measured results were between 1.3% and 6.6%.The recoveries were between 95% and 101%.