YSI 9300 Photometer - Manual (Page 111)

Test Procedure
1 Filter sample if necessary to obtain a clear solution.
2 Fill test tube with sample to the 10 ml mark.
3 Add one Molybdate No 1 LR tablet, crush and mix to dissolve.
4 Add one Molybdate No 2 LR tablet, crush and mix to dissolve.
5 Stand for two minutes to allow full color development.
6 Select Phot 42 on the photometer.
7 Take Photometer reading in the usual manner (see photometer instructions).
8 The result is displayed as mg/l MoO
4
.
Note
Molybdate concentrations can be expressed in a number of different ways. The
following factors may be used for the conversion of results :-
To convert from MoO
4
to Na
2
MoO
4
- multiply by 1.3
To convert from MoO
4
to Mo - multiply by 0.6.
Interferences
1 Copper 20 mg/l, zinc 20 mg/l, phosphate 100 mg/l and calcium 200 mg/l do
not interfere in this test.
2 Iron 10 mg/l and chlorine 10 mg/l cause slightly high blank readings equivalent to
0.6 mg/l Mo. However, they do not cause any interference in samples which
contain molybdate.
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