Several types of water systems are available including reagent grades I, II
or III and these must all be checked for sterility and conductivity on a
periodic basis. Distilled and deionized water are NOT considered reagent
grade and are not subject to being checked. I prefer reagent type II water
for all my solutions and as a final rinse for my glassware. Type II grade
systems are available in both standard and high flow/capacity versions, with
and without a built-in ultraviolet sterilizers, for operation on either
pretreated water or under your sink from tap water. 

The NCCLS Tentative Standard Specifications for Reagent Grade Water Used in
the Clinical Laboratory lists them as follows:

Type I - Tissue and/or cell culture methods; ultra-micro chemical analyses
where accuracy at nanogram and sub-nanogram levels is necessary; preparation
of standard solutions.

Type II - Most routine clinical laboratory methods in chemistry, immunology,
hematology and other areas.

Type III - Most qualitative procedures; most procedures in urinalysis,
parasitology and histology; glassware washing; general laboratory tests not
requiring type II or better water.

Silicate concentrations greater than 0.05 mg/L can interfere with enzyme and
metal staining. The lab should contact the public water department for a
listing of possible laboratories that can test to the required level or you
can do the silica testing yourself, I do. The NCCLS inspection checklist
does not specify a frequency for this testing, it is to be performed, as
they say, "at the discretion of the laboratory". The NCCLS guideline (C3-A2)
may be of more assistance. 

Write for the latest copy of NCCLS Specifications for Reagent Water to:

NCCLS
940 West Valley Road, # 1400
Wayne, PA  19087-1898  

or check them out online at http://www.nccls.org



Eric C. Kellar


> ----------
> From: 	Brad Heck[SMTP:heckler_59@yahoo.com]
> Sent: 	Friday, June 23, 2000 8:32 PM
> To: 	Histonet
> Subject: 	Water
> 
> Can anyone help me with the water type needed for all
> types of special stains, i.e. immuno's, metal stains,
> gram stains etc.. We are currently remodeling our
> laboratory and I want to replace our current large
> deionized tank model with a model that will install
> under the sink and let us have water on tap. I
> requested Type 1 water because I was afraid of
> contamination both on gram stains, and all metal
> stains. The administration is reluctant to buy the
> filtration system needed to provide Type 1 because
> they say none of our procedures specify water type
> (Type 1 is more expensive). Is there current
> literature stating specific water types?
> 
> Jeannie 
> heckler_59@yahoo.com 
> 
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