Tips from daily practice: Ultrapure water for ion chromatography 

The traditional classification of water quality in accordance with such standards as ASTM, ISO, CAP/NCCLS, or USP is no longer sufficient for the increasing sophistication of the applications. New analysis techniques, in conjunction with ever greater sensitivities, require improved water quality. Taking these manifold requirements into account, Sigma-Aldrich produces a variety of water qualities, for which each individual product is tailored to a specific application.