220.127.116.11. Planning the Test.
Read the Test Procedure. Read the test procedure all the way through before conducting a test. Check to see
that all the needed equipment and reagents are readily available.
Multiple Samples of Water. Best results are obtained by testing samples from several locations and depths and
at different times. A single sample of water may not truly represent the body of water being tested.
Repeat Tests for Accuracy. Greater accuracy and confidence in results can be had by testing each sample two
or three times. If a second test on the same sample or sample taken from the same location at the same time
produces results identical to the first test, this is a good indication that the results are valid. If the second test
differs significantly from the first test, perform additional tests until a consistent result is obtained.
Time Lapse. As little time as possible should lapse between collecting the sample and making the analysis.
Test Temperatures. Ideally the tests should be done with sample temperature between 68°F (20°C) and 77°F
(25 °C). If a test requires closer temperature control, it will be noted in the procedure.
Be Accurate. Be careful with measurements and handling of reagents and sample. Spilling even a small
amount of measured sample or reagent may cause major errors.
Make Records. Test results should be recorded as they are determined. It is a good idea to record where the
sample was taken, the day and time, the temperature, and name of the person making the tests.
Check Reagents. Check reagents before use for any visible sign of contamination. Check the expiration dates.
Use Clean Labware. Only clean and dry labware should be used. If in doubt, clean all labware before
performing a test. (See para 18.104.22.168 below.) j. Test Ranges. WQAS-PM low-range tests are generally more
accurate than high-range tests. Sometimes the approximate result of a test will be known ahead of time. If this
expected result is within the low range, try that test first. If the actual result of a low-range test is at the upper
end of the range, it is a good idea to confirm with a high-range test. If there is no advance information, it is
usually better to do the high-range test first. Then, if the measured results are low enough, perform the low-
22.214.171.124. Cleaning Glassware.
Cleaning labware is a very important part of using the WQAS-PM. All labware should be cleaned immediately after use
and before storing the equipment.
Dirty glassware may cause inaccurate test results.
Use clean water and the detergent and brushes provided in the WQAS-PM to clean labware.
Ensure that all glassware is thoroughly clean after each use and before putting it back in the WQAS-PM.
Clean immediately after use. Do not let chemicals dry on labware. It is much more difficult to clean equipment,
if not cleaned immediately after use.