甲烷动态反应电感耦合等离子体质谱法测定地下水中痕量硒

刘金巍; 刘雪松; 边超; 张涛; 张智印; 魏建朋

doi:10.15898/j.cnki.11-2131/td.201804200049

甲烷动态反应电感耦合等离子体质谱法测定地下水中痕量硒

Determination of Trace Selenium in Groundwater by DRC-ICP-MS

摘要

摘要: 地下水中的硒含量一般低于1μg/L，大量氯离子等形成的多原子离子干扰和较低的电离程度，严重影响常规模式ICP-MS测定地下水中痕量硒的准确性，且检出限难以满足实际需要。本文建立了应用动态反应池电感耦合等离子体质谱（DRC-ICP-MS）技术测定地下水中痕量硒的方法，采用乙醇为增感剂，甲烷为反应气，通过实验优化了甲烷流量、乙醇含量、雾化气流速、低质量截取（RPq）、射频发生器（Rf）功率、离子驻留时间等条件对硒不同质量数测定的影响。结果表明：乙醇、甲烷可显著降低Ar等形成的多原子离子干扰，乙醇可明显提高硒的响应强度；在优化实验条件下，除⁷⁴Se外，各离子的校准曲线线性关系良好（R ≥ 0.9996），方法检出限为0.02~0.03μg/L，低浓度和高浓度样品测试结果的RSD < 2%（n=5），平均加标回收率为95.7%。本方法样品前处理简单，使用设备单一，可满足大批量地下水中痕量硒的测定要求。

Abstract:
BACKGROUNDGenerally, the content of Se in groundwater is lower than 1μg/L. Mass interferences caused by polyatomic species and low ionization degree can seriously affect the accuracy for determination of trace and ultratrace Se in groundwater by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Moreover, the current detection limit is higher than required for practical purposes.
OBJECTIVESTo establish DRC-ICP-MS method for determination of trace selenium in groundwater.
METHODSEthanol was used as a signal enhancer, methane was used as a reaction gas. The factors that affect different mass determination, including methane flow, ethanol content, atomizing gas flow rate, low mass interception (RPq), RF generator (Rf) power, ion residence time were discussed and optimized.
RESULTSEthanol can increase response values, whereas ethanol and methane can obviously eliminate the mass spectrometry interference. Under the optimized conditions, except ⁷⁴Se, calibration curves show a good relationship (R > 0.9996). The method detection limits are 0.02-0.03μg/L, the relative standard deviation (RSD, n=5) is lower than 2%, and the average spiked recovery is 95.7%.
CONCLUSIONSThe method has simple pretreatment and single equipment, which can meet the requirements for determination of trace selenium in large quantities of groundwater.

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