TM 10-6630-245-13&P
e.
Test Procedure:
WARNING
High voltage used with Spectrophotometer. Misuse can cause electrical shock and damage
equipment. When operating with 115V or 220V power, make sure the power source and
equipment are in ground potential. Ensure that the power cable connections are correct for the
desired voltage power before connecting the power source.
CAUTION
Accurate volume measurements are very important for this test.
NOTE
The fluoride test is sensitive to interference by small quantities of other chemicals. Glassware
must be absolutely clean. If and when repeating a test, the possibility of contamination by other
chemicals can be reduced by using the same glassware as first used for the test.
NOTE
Keep the water sample and the fluoride standard solution at the same temperature. At least
within one degree. Best results are obtained when both are at 68 °F (20 °C).
(1)
Refer to para 2.6.2 for set up and operation of the Spectrophotometer.
(2)
Use the 25 ml volumetric flask(32, fig. 1-1) to collect the water sample. Rinse the flask(32) with sample
water at least three times. Fill the volumetric flask(32) accurately to the 25 ml mark with a sample of the
water to be tested.
NOTE
If water samples are to be collected for later analysis, a clean polyethylene plastic bottle is the
best container if available. Rinse the bottle several times with water from the test source before
collecting the sample.
(3)
Pour the measured 25 ml sample into a clean dry spectrophotometer sample cell (7, fig. 2-5).
WARNING
FLUORIDE STANDARD SOLUTION POISON. Harmful if swallowed. Do not ingest or allow
contact with skin or eyes. In case of eye or skin contact, flush with plenty of water. In case of
ingestion, give large quantities of water or milk. Call medic immediately.
(4)
Shake all the test water out of the 25 ml volumetric flask(32, fig. 1-1). Fill the flask(32) accurately to the
25 ml level with fluoride standard solution(15).
(5)
Pour the 25 ml of fluoride standard solution into the other clean and dry spectrophotometer sample cell(7,
fig.2-5).
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