顶空气相色谱/质谱法测定水中四乙基铅的关键因素研究

采用顶空气相色谱/质谱法联用技术测定水中的四乙基铅,对涉及的关键操作环节及重点技术问题进行了研究。结果表明,在避光条件下于4℃低温冷藏并密封保存,添加甲醇作为保护剂,保存时间不应超过3 d。实验选择进样口温度为220℃,顶空瓶压力为96.52 kPa,调节载气流量设置实际分流比为51,可以有效改善顶空进样测定样品时存在的不出峰、不稳定或灵敏度降低的问题。对地表水、自来水及生活污水实际样品进行四乙基铅测定和加标回收分析,加标回收率为81.0%~110%,相对标准偏差(RSD)为2.5%~7.4%,能够满足《水质四乙基铅的测定顶空/气相色谱质谱法》(HJ 959—2018)的测定要求。将顶空进样法与吹扫捕集法进行比较,结果表明顶空进样法稳定性更好,适合大批量四乙基铅样品的连续测定。

The Key Factors in Determination of Tetraethyl Lead in Water with Headspace Injection Gas Chromatography/Mass Spectrometry

A headspace injection-gas chromatography-mass spectrometric(HS-GC/MS)method was used to analyze tetraethyl lead in water.The key operational steps and technical issues were studied.The results showed in sealed bottle and kept dark at 4℃,the storage time is no more than 3 days by adding methanol as a protective agent.By setting the inlet temperature at 220℃and the headspace bottle pressure at 96.52 kPa,and adjusting the split ratio to 5∶1,it could efficiently improve the problems of no peak,instability or reduced sensitivity in the determination of tetraethyl lead samples.For standard addition analysis on real water samples,the range of recovery was 81.0%to 110%,with the RSDs ranged from 2.5%to 7.4%,it could meet the requirements set by"water quality determination of tetraethyl lead headspace/gas chromatography mass spectrometry"(HJ 959—2018).Compared with purge and trap-gas chromatography-mass spectrometry,headspace injection was more stable and suitable for continuous determination of large quantities of tetraethyl lead samples.