采用带六极杆碰撞反应池的电感耦合等离子体质谱直接测定了生物样品中痕量铬和钒.在碰撞反应池中引入He/NH3(93∶7)混合气,有效地消除了分子离子(ArC+、NCl+、ClO+、ClOH+等)对超痕量铬、钒测定的干扰,降低了方法的检出限.比较了干法灰化和湿法消解两种样品处理方法,两种消解方式获得的结果基本一致.方法的检出限(3σ):钒为0.005 0 μg·g-1,铬为0.001 8 μg·g-1.相对标准偏差:钒为3.25%~14.08%;铬为4.20%~8.24%.经国家一级生物标准物质验证,测定值与标准值吻合.

Traces of chromium and vanadium in biological samples were determined by ICP-MS using the hexapole collision cell technique. Gas mixture of He and NH3 in the proportion of 93 to 7 was introduced into the collision cell to eliminate effectively the interferences of molecular ions of ArC+,NCl+,ClO+,ClOH+ and etc. to the determination of ultra-trace amounts of chromium and vanadium,and thus the detection limits (D.L.) of the method were lowered. The values of D.L. (3σ) were found as: for vanadium 0.005 0 μg·g-1,and for chromium 0.001 8 μg·g-1. A comparative study was made on the treatment of sample by the dry ashing method and the wet digestion method,and as shown by the results obtained,no significant difference was found. Precision tests,made on different concentration levels,gave values of RSD′s (n=12) in the ranges of 3.25%-14.08% (for vanadium) and of 4.20%-8.24% (for chromium). In the analysis for checking the accuracy of the present method with some SRM′s,the analytical results obtained were in consistency with the certified values.