2-14. REQUIREMENTS FOR STANDARDS AND REAGENTS
The following are recommended requirements for all water used in the laboratory
for the preparation of standards and reagents.
Requirement
Level
Ammonia
Less than 0.1 mg/L
Dissolved carbon dioxide
Less than 3 mg/L
PH
6.0 to 7.0
Sodium
Less than 0.1 mg/L
2-15. CARBON-DIOXIDE-FREE WATER
a. Carbon-dioxide-free water can be prepared by boiling Type II water for 20
minutes in an acid washed chemically resistant glass flask (such as Pyrex or Kimax
brand borosilicate glass).
b. Remove the heat source and immediately close securely with a stopper fitted
with a soda lime drying tube or a NaOH air trap and allow to cool.
c.
d. Carbon-dioxide-free water should be used for prothrombin times, certain
reference buffers, and National Bureau of Standards (NBS) standards. It is also
recommended that lyophilized material be reconstituted with carbon-dioxide-free water.
The specifications described by the College of American Pathologists (CAP) on
water quality should be applied in performing a water quality check. These
specifications should be checked weekly on both flowing and stored water. The check
site of the test should be identified and the results compared to established limits and
logged on an appropriate chart. If results exceed established limits, corrective
measures must be taken according to CAP guidelines and a record of action taken
placed in the log.
Section III. PARTS OF A SOLUTION
2-17. INTRODUCTION
In order to discuss a solution, one first needs a definition of the term. A solution
is a homogeneous mixture of gases, solids, or liquids in which the individual molecules
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