Optimal water quality in the laboratory requires the best source of pure water. Even though there are a number of purification technologies available, no single technology will remove all the contaminants to levels low enough for laboratory use. Thus, a combination of technologies is recommended.
The combination of RO and EDI is the best choice for producing Type 2 water. The ion and TOC levels of RO-EDI water are consistently low, meeting the needs of many general laboratory applications, and for use in clinical analyzers. Also, the consistent quality of RO-EDI water makes it most suitable for producing ultrapure water with a polishing system such as a Milli-Q system. The result is ultrapure water with consistently low levels of ions and TOC. Other sources of pure water, such as distillation, SDI, and even the combination of SDI and distillation have been shown to produce polished water with fluctuating contaminant levels. Such fluctuation compromises the quality of data obtained from modern analytical instruments where trace and ultra trace analyses are possible.
Finally, in addition to choosing the best technologies based on a sound understanding of water quality, it is important that laboratory personnel be trained in the proper use and maintenance of the systems, and that appropriate water quality parameters be monitored on a regular basis. Using a system equipped with resistivity and TOC monitoring capabilities allows users to check the quality of water being delivered.
This cleanroom tip was taken from “Water, Water Everywhere” by Estelle Riche, Cecilia Devaux, and Stephane Mabic. The article originally appeared in the November/December 2015 issue of Controlled Environments.