离子色谱-串联质谱法测定工业废水中的六价铬残留

Determination of hexavalent chromium residue in industrial waste water by ion chromatography-tandem mass spectrometry

基于弱阴离子交换(WAX)小柱富集水样中的六价铬,三价铬则不被小柱保留而直接被去除,采用AS20柱分离、KOH溶液为淋洗液洗脱,采用串联四极杆质谱在电喷雾电离负离子模式下多反应监测模式(MRM)测定六价铬。研究了样品的净化条件、三价铬的去除和色谱质谱条件。结果表明,六价铬质量浓度在1.0~200μg/L范围内呈良好的线性,相关系数(R2)优于0.9995,方法定量限(LOQ)和检出限(LOD)分别为为1.0和0.3μg/L,加标回收率在72.5%~94.0%之间,相对标准偏差(RSD)为5.2%~8.6%。用所建立的方法对本地区代表性的51个工业废水样品进行了测定。

This method is based on the weak anion exchange( WAX) cartridge which can enrich hexavalent chromium in the water samples,while trivalent chromium was not retained by the cartridge and was directly removed. Sample separation was carried out on an AS20 column using KOH aqueous solution as eluent elution,and determination was carried out using tandem quadrupole mass spectrometry by negative electrospray ionization in multiple reaction monitoring( MRM) mode. The research focused on the purification of the samples,the removal of trivalent chromium and the optimization of the chromatographic and mass spectrometric conditions.Results indicated that the linear range of hexavalent chromium was 1. 0-200 μg/L,the correlation coefficients were greater than 0. 9995;besides,the limit of quantification( LOQ) was 1. 0 μg/L and the detection limit( LOD) was 0. 3 μg/L. In addition,the recoveries were 72. 5%-94. 0% and the relative standard deviations( RSD) were 5. 2%-8. 6%. Finally,the established method was used to determine 51 representative industrial wastewater in the region.