CLINICAL LAB SCIENEC

CHAPTER 9: LABORATORY MATHEMATICS 217
Type I
Type I is the purest type of reagent water for certain procedures where maximum
quality is required and where measurements of analytes are in nanograms (ng)
or subnanograms.
Type II
This type of water may contain microorganisms but is suitable for most procedures
in the clinical laboratory and other clinical test areas.
Type III
Type III water may be used in urinalysis procedures, and in washing and rinsing
laboratory glassware. However, a final rinsing with Type I or Type II water may
be necessary based on methods for which this glassware will be used.
Methodology for Preparing Pure Water
Water obtained from areas with industrial contamination of water and soil, such
as inorganic and organic materials from farming, may contain materials that
no single purification system can remove. Sometimes more than one method is
used to prepare water for laboratory use, such as deionization and distillation.
For instance, distilled water may be treated by a deionization process to obtain
a higher degree of purity. The presence of ionizable materials in water can be
measured by the conductance or electrical resistance of the water being tested.
Most deionizers and distillers have purity meters which warn the user if there is
an unacceptable level of contaminants.
Deionized Water
Substances that can ionize (form charged particles) are passed through resin columns
that contain both positively and negatively charged particles. The ions in
the water will combine with the particles in the resin columns but some organic
and other substances that do not ionize will not be removed, and will require
other removal methods. Type I water is produced by this method.
Distilled Water
Distilled water is made by a simple process of boiling the water and allowing the
steam to condense on a surface. Distilling water removes minerals found in natural
water sources. This process produces Type II and Type III water. The method
eliminates microorganisms but the water may contain carbon dioxide, chlorine,
and ammonia.
Other Methods of Purifying Water
Water of higher purification may be produced by using both deionization and
distillation, while other methodologies are also available. Reverse osmosis is a
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