YSI 9300 Photometer - Manual (Page 110)

PHOTOMETER TEST INSTRUCTIONS
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Formulations containing molybdate are used as corrosion inhibitors in industrial
water treatment. In particular, low level molybdate treatment finds application in
cooling systems. Molybdate based formulations have replaced older forms of
corrosion inhibitors.
When using molybdate treatment it is necessary to control the molybdate
concentration within specified levels depending on the application involved.
Moreover, since molybdates are widely used in water treatment and in industrial
processes, molybdate is an increasingly important test for effluents and industrial
discharges.
The YSI Molybdate LR test provides a simple means of measuring low levels of
molybdate in industrial waters and effluents and covers the range 0 - 20 mg/l
MoO
4
(0 – 12 mg/lMo).
Method
Molybdates react with a dihydroxybenzene disulphonlc acid salt under slightly
acid conditions to give a yellow colored complex. Under the conditions of the
test, iron does not interfere and there is no significant interference from other
metals at levels likely to be found in industrial water systems (see Notes). The
reagents are provided in the form of two tablets for maximum convenience. The
test is simply carried out by adding one of each tablet to a sample of water.
The intensity of the color produced in the test is proportional to the molybdate
concentration and is measured using a YSI Photometer.
Reagents and Equipment
YSI Molybdate No 1 LR Tablets
YSI Molybdate No 2 LR Tablets
YSI 9300 or 9500 Photometer
YSI Photometer Round Test Tubes, 10 ml glass (PT 595)
Photometer Method
AUTOMATIC
WAVELENGTH
SELECTION
0 – 20 mg/l MoO
4
PHOT.42.AUTO