两种微波等离子体炬质谱测定水中铅的对比研究

建立了一种新型的能够灵敏分析水中痕量铅的质谱方法,以微波等离子体炬(MPT)为离子源,可无需样品预处理而直接分析水样。样品经雾化和去溶后由MPT的中心管道引入等离子体,离子由国产的四极杆质谱仪(Q-MS)检测,得到铅的MPT特征质谱。定量结果表明,该方法的检出限为20 ng/L,线性范围为200~1 000 ng/L,相对标准偏差(RSD)为5.3%;所得定量指标优于相同条件下商用的线性离子阱质谱(LTQ-MS)测试结果,且四极杆质谱仪上所得的铅离子特征质谱信号更简单、易归属,无需复杂的多级串联质谱加以确认。这种MPT可与国产质谱仪器相结合发展成为一种低成本的现场检测铅的质谱仪器,在环境监控、饮用水检验等方面具有一定的应用价值。

Direct Detection of Lead in Aqueous Solution Using Two Kinds of Microwave Plasma Torch Coupled with Mass Spectrometry

A sensitive mass spectrometric approach was developed for the detection of trace lead in water.The microwave plasma torch(MPT) was used as the ion source for direct analysis of water samples without any pretreatments.Aqueous samples were introduced in the plasma through the central cube of the MPT after nebulization and dying,the generated ions were detected by a homemade quadrupole mass spectrometer(Q-MS).The quantitative results showed that the limit of detection(LOD) was at the level of 20 ng/L,and the linear range was 200-1 000 ng/L with RSD of 5.3%.These quantitative indexes were better than the results from the international commercial linear ion trap mass spectrometer(LTQ-MS) under the same MPT working conditions.However,the characteristical mass spectra obtained on MPT-Q-MS were simpler and easier to be assigned without further MSn experiments,thus MPT coupled with Q-MS will be suitable for the development of the portable analysis instrument,and have the potential applications in environmental controlling and drinking water detection.