Jackson Brian P
Department of Earth Sciences, Dartmouth College, Hanover, NH 03755.
J Anal At Spectrom. 2018 May 1;33(5):897-900. doi: 10.1039/C8JA00073E. Epub 2018 Apr 17.
Determination of low concentrations of Ga in environmental or biological samples can benefit from interference free measurement of both Ga isotopes. Unfortunately, both isotopes have potential interferences, i.e doubly charged Ba at m/z 69 and MnO at 71. Analysis using collision and reaction gases by ICP-QQQ as an alternative to HR-ICP-MS is investigated here using conventional nebulization and a desolvating nebulizer. Analysis at m/z 71 is not appreciably affected by MnO at 200 ug/l Mn or in either water reference material; excellent detection limits of < 0.1 ng/l were obtained for He, H, or on-mass O and NH gas modes. Analysis of Ga at m/z 69 was severely affected by doubly charged Ba across all gas modes except +17 mass-shift (i.e. 69 - 86) NH gas mode. Despite Ga being only 1-2% reactive at the 69-86 mass shift, the doubly-charged interference was not mass-shifted and detection limits of < 1 ng/l and precise and accurate quantification of two water reference materials and nine natural water samples were achievable for this analysis mode.
测定环境或生物样品中的低浓度镓，可受益于对两种镓同位素进行无干扰测量。不幸的是，这两种同位素都存在潜在干扰，即在质荷比为69时的双电荷钡以及在71时的MnO。本文研究了使用碰撞和反应气体，通过电感耦合等离子体质谱仪（ICP-QQQ）作为高分辨率电感耦合等离子体质谱仪（HR-ICP-MS）的替代方法，采用常规雾化器和去溶剂化雾化器进行分析。在200微克/升的锰浓度下或在两种水标准物质中，质荷比为71时的分析不受MnO的明显影响；在氦气、氢气或质量数为16的氧气和氨气模式下，获得了<0.1纳克/升的出色检测限。除了+17质量偏移（即69-86）氨气模式外，在所有气体模式下，质荷比为69时的镓分析都受到双电荷钡的严重影响。尽管在69-86质量偏移下镓的反应性仅为1%-2%，但双电荷干扰并未发生质量偏移，对于该分析模式，可实现<1纳克/升的检测限以及对两种水标准物质和九个天然水样的精确和准确定量。
