Preparation of ultra-pure water and acids and investigation of background of an ICP-MS laboratory.

Ultra-pure water is prepared by distillation, and followed by ion exchange and passing through an E-PURE water purifier. The resulting ultra-pure water has an electrical conductivity of 18 MOmega. Ultra-pure nitric, hydrochloric, hydrofluoric and perchloric acids are prepared by sub-boiling distillation. Spectra for mass range 3-240 amu are scanned by inductively coupled plasma mass spectrometry for tap, distilled, deionized and ultra-pure waters, and extra- and ultra-pure acids. The results show that the sub-boiling distillation greatly improves the quality of all the four acids under investigation. Metal impurities such as 75, 93, 121, 123, 134-138, 181 and 206-209 amu were remarkably reduced (sub-ppb level) after sub-boiling distillation. Configuration of peaks due to the formation of polyatomic ions was similar to the literature values reported elsewhere (S.H. Tan, G. Horlick, Appl. Spectrosc. 40 (4) (1986) 445).