grade water is actually a broad term applied to water purified for
laboratory uses. It has been defined at three or four distinct purity
levels or types by professional societies concerned with the quality,
uniformity and reproducibility of tests or materials requiring purified
water. The precise definitions of each water type, however, vary
from society to society. So your specific reagent grade water needs
will depend primarily on the intended use of the water, using specifications
offered by the society most applicable to your situation as a guideline.
In the clinical laboratory field, the College of American
Pathologists (CAP) and the National Committee for Clinical Laboratory
Standards (NCCLS) have published or proposed standards for reagent grade
water. For other laboratories, the American Society for Testing and
Materials (ASTM) and the American Chemical Society (ACS) have
established standards. A summary of specifications for each grade of
water is contained in the Reagent Grade Water Specification Table.
general, Type I water is used for procedures requiring maximum accuracy
and precision such as HPLC, atomic absorption spectrometry, flame
photometry, enzymology, blood gas, pH, and specific ion determinations,
reference buffer solutions, and the reconstitution of lyophilized
materials used as standards. Type II is designated for most analytical
and general laboratory testing and hematological, serological and
microbiological procedures. Type III is suitable for most qualitative
analyses, urinalysis, parasitology and histological procedures,
the making of stock solutions, and rinsing of laboratory glassware.
Grade Water in CAP Accreditation
The College of American Pathologists, beyond its definitions
of reagent grade water, has also included in its accreditation checklist
certain mandatory and recommended procedures concerning laboratory
purity water. For example, laboratories seeking CAP accreditation
must have a system in use, with written procedures, for checking
purity of water. A permanent record of purity checks, to verify
conformation to reagent grade specifications, must be maintained.
Specifically recommended checks are resistivity, pH, hardness, sodium,
ammonia, and cultures.
makes no representation that these standards are suitable for your
USES OF REAGENT GRADE WATER
systems (not to be sterilized)
& dyes (histology/parasitology)
systems (to be sterilized)
analysis HLA testing w/ ultrafilter
selected purposes, additional requirements beyond those specified
for Type I water may not be necessary. This chart lists several
of these selected purposes.
the standards of water
purity, which features guidelines from the National Committee
for Clinical Laboratory Standards (NCCLS), the College of American
Pathologists (CAP), and the American Society for Testing Materials
TREATMENT APPLICATION DATA