YSI 9300 Photometer - Manual (Page 105)

Reagents and Equipment
YSI Alkaphot M Tablets
YSI Alkaphot P Tablets
YSI 9300 or 9500 Photometer
Round Test Tubes, 10 ml glass (PT 595)
Test Procedure - Alkaphot M
1 Filter sample if necessary to obtain a clear solution.
2 Fill the test tube to the 10 ml mark with sample.
3 Add one Alkaphot M tablet, crush and mix. Ensure all particles are dissolved.
4 Select Phot 37 on the photometer.
5 Take photometer reading in the usual manner.
6 The result is displayed as mg/l CaCO
3
.
Test Procedure - Alkalinity P
1 Filter sample if necessary to obtain a clear solution.
2 Fill the test tube to the 10 ml mark with sample.
3 Add one Alkaphot P tablet, crush and mix to dissolve.
4 Stand two minutes to allow complete color development.
5 Select Phot 38 on the photometer.
6 Take photometer reading immediately in the usual manner.
7 The result is displayed as mg/l CaCO
3
.
Alkalinity Relationships
From the results obtained from the foregoing procedures it is possible to classify
the sample into the three main chemical forms of alkalinity present in most
waters, namely hydroxides, carbonates and bicarbonates. This calculated
relationship assumes the absence of other weak forms of alkalinity and also
assumes that hydroxides and bicarbonates are not compatible in the same
sample. The chemical forms of alkalinity, expressed as mg/l CaCO
3
are calculated
by the following equations:-
a) If Alkalinity P = 0
b) If Alkalinity P > 0 and M > 2P
Then Bicarbonate = M Then Bicarbonate = M - 2P
Carbonate = 0 Carbonate = 2P
Hydroxide = 0 Hydroxide = 0
c) If Alkalinity P > 0 and M < 2P
Then Bicarbonate = 0
Carbonate = 2M - 2P
Hydroxide = 2P – M
Where P and M are the results of the Alkaphot P and Alkaphot M tests respectively.