Pharmaceutical: Updating International Standards For Pharmaceutical Waters

Historically, quality tests for bulk purified water (PW) and water for injection (WFI) were confined to the laboratory. Water samples were checked for single chemical impurities, such as carbon dioxide, ammonia, chloride, sulfate, and calcium, using traditional wet chemistry methods. Other wet chemistry tests for screening classes of impurities included oxidizable substances, heavy metals, and pH. These tests complemented other existing tests for particulates, micro-organisms, and endotoxins. In some pharmacopoeia, tests for nitrate, nitrites, and other impurities were also required.

As far back as 1989, the United States Pharmacopoeia (USP) and the Pharmaceutical Research and Manufacturers of America (PhRMA) began investigating alternatives to the wet chemistry tests. At that time, the principal focus was not on the water, but on the reliability of the water testing.