Determination of trace silicon in ultra-high-purity water by inductively coupled plasma mass spectrometry

Abstract

Determination of trace levels of Si in ultra-high-purity water was performed by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Instrumental background, especially from the plasma torch is a serious problem. To overcome this problem a careful preconcentration procedure was adopted. This procedure allows excellent quantification down to sub-ng l^–1 level. Total Si concentration is obtained regardless of the chemical state of Si. Consequently, by subtracting ionic Si, determined by colorimetric analysis, from total Si, it may be possible to obtain the concentration of non-ionic Si. Total Si concentration levels in semiconductor-grade water samples ranged from 0.5 to 1.0 ng g^–1.