YSI 9300 Photometer - Manual (Page 80)

Reagents and Equipment
YSI Molybdate No 1 HR Tablets
YSI Molybdate No 2 HR Tablets
YSI 9300 or 9500 Photometer
Round Test Tubes, 10 ml glass (PT 595)
Test Procedure
1 Fill round test tube with sample to the 10 ml mark.
2 Add one Molybdate No 1 HR tablet, crush and mix to dissolve.
3 Add one Molybdate No 2 HR tablet, crush and mix to dissolve.
4 Select Phot 22 on photometer.
5 Take photometer reading in usual manner (see photometer instructions).
6 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 readings :-
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
The presence of Fe
2+ (ferrous) or Fe 3+ (ferric) iron at 5 mg/l causes the rapid
development of a red color in the test. This may be prevented by the treatment
of the 10 ml sample with one YSI EDTA tablet prior to carrying out the test.
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