氢化物发生-液体阴极辉光放电发射光谱对海水中硒、砷、汞的高灵敏定量检测

Highly Sensitive Determination of Selenium, Arsenic and Mercury in Seawater by Hydride Generation Coupled with Solution Cathode Glow Discharge Optical Emission Spectrometry

通过将氢化物发生装置与液体阴极辉光放电发射光谱仪相耦合,建立了一种定量检测海水中痕量硒、砷、汞的方法。实验对氢化物发生的载酸种类和浓度、还原剂浓度以及液体阴极辉光放电装置的放电电压、电解质种类和流速等工作条件进行了优化,确定了联用仪器定量分析硒、砷、汞的最佳工作条件:氢化物发生载酸为5%的HCl,还原剂为1.5%的NaBH_4,液体阴极辉光放电装置的放电电压为1060V,电解质溶液为pH 1的HCl,电解液流速为2.2 mL·min^(-1)。分别选取204.0, 228.8和253.7 nm作为硒、砷、汞的分析谱线,在上述最佳工作条件下对硒、砷、汞的系列混合标准溶液进行测定,硒、砷、汞的质量浓度在2～100μg·L^(-1)范围内与其发射强度呈线性关系,线性相关系数分别为0.999 2, 0.999 4和0.998 5,其检出限分别达到0.54, 0.92和1.91μg·L^(-1),浓度为0.1 mg·L^(-1)的硒、砷、汞的信号值相对标准偏差均小于3%。与单一的液体阴极辉光放电发射光谱相比,硒、砷、汞的检出限分别降低了3个、 4个、 2个数量级。选取国家土壤标准物质GBW07405对联用仪器检测结果的准确度进行了验证,其检测值与参考值一致;将该方法应用于中国黄海沿岸实际海水样品中痕量硒、砷、汞的定量分析,分析结果与电感耦合等离子体质谱法一致,用标准加入法测得其加标回收率在94.9%～105.3%之间。氢化物发生-液体阴极辉光放电发射光谱能够实现快速、准确地对海水中痕量硒、砷、汞的高灵敏在线定量检测。

In this paper, the trace amounts of selenium, arsenic and mercury in seawater were quantitatively detected by coupling hydride generation (HG) device with solution cathode glow discharge optical emission spectrometry (SCGD-OES). Instrument conditions were optimized, and the optimal instrument conditions for quantitative analysis of selenium, arsenic and mercury were determined: 5% HCl as the carrier acid for subsequent experiments, 1.5% NaBH 4 as the reducing agent, the SCGD parameters of the electrolyte, discharge voltage, and flow rate were maintained at pH 1 HCl, 1 060 V, and 2.2 mL·min^-1 , respectively. Element wavelengths of 203.4, 228.8 and 253.7 nm were selected as the analytical lines of selenium, arsenic and mercury, and the mixed standard solutions of selenium, arsenic and mercury were determined under the optimal working conditions simultaneously. The mass concentration of selenium, arsenic and mercury is linear with the emission intensity in the range of 2~100 μg·L^-1 , and the linear correlation coefficients are 0.999 2, 0.999 4 and 0.998 5, respectively. The detection limits were 0.54, 0.92 and 1.91 μg ·L ^-1 . The relative standard deviations of the signal values of selenium, arsenic and mercury are less than 3% at a concentration of 0.1 mg·L^-1 . Compared with SCGD-OES, the detection limits of selenium, arsenic and mercury are reduced by three, four and two orders of magnitude, respectively. Soil reference material GBW07405 was selected to verify the accuracy of the results of the coupling instrument, and the measured value was consistent with the reference value. The method has been applied to the analysis of trace selenium, arsenic and mercury in seawater samples from the Yellow Sea coast of China and the analysis results are in agreement with those of ICP-MS. The recoveries of standard addition are between 94.9% and 105.3%. HG-SCGD-OES enables highly sensitive on-line quantitative detection of trace amounts of selenium, arsenic and mercury in seawater.