YSI 9300 Photometer - Manual (Page 32)

Sample Collection
Aluminum is readily absorbed on to the surfaces of sample containers, particularly
glass containers. To avoid loss of aluminum, collect samples in plastic bottles and
test as soon as possible after collection. Sample bottles should be acid-rinsed and
thoroughly washed out with deionised water before re-use.
Test Procedure
1 Fill test tube with sample to the 10 ml mark.
2 Add one Aluminum No 1 tablet, crush and mix to dissolve.
3 Add one Aluminum No 2 tablet, crush and mix gently to dissolve. Avoid vigorous
agitation.
4 Stand for five minutes to allow full color development.
5 Select Phot 3 on photometer.
6 Take photometer reading in usual manner (see photometer instructions).
7 The result is displayed as mg/l Al.
Interferences
The presence of polyphosphate or fluoride can lead to low aluminum readings.
Polyphosphate is unlikely to be present in significant quantities in normal water
samples. Fluoride will only be significant for control samples from water works
where fluoridation is practised. In such cases samples should preferably be taken
before the final fluoridation stage.
For samples taken after fluoridation such as those from water distribution systems, or
for samples containing natural fluoride, the aluminium concentration should be
corrected. To obtain the corrected aluminum concentration multiply the calibration
chart value by the factor (1 + 0.4 F) where F is the Fluoride concentration as mg/l F.
The fluoride concentration should be determined separately by normal test procedure.
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