LaMotte DC1600 Colorimeter - Manual (Page 53)

MOLYBDENUM
TIRON METHOD CODE 3657
QUANTITY CONTENTS CODE
60 mL pH 7.0 Buffer 2881-H
5 g *Tiron Powder *6045-C
30 mL *Sodium Hydroxide, 0.2N *5168-G
1 pHydrion Test Papers 2953
2 Resin Columns 1079
2 Pipets, 1.0 mL, plastic 0354
1 Spoon, 0.1 g, plastic 0699
1 Test Tube, 5, 10, 12.9, 20 & 25 mL, glass, w/cap 0608
1 Demineralizer Bottle 1151
1 Rod, plastic, stirring 0519
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are supplied for
these reagents. For your safety read label and accompanying MSDS before using.
Molybdenum occurs naturally in the earth’s crust as molybdenite and wolfenite, and is an important element in many
biochemical reactions, including nitrogen fixation. In industrial processes, such as the operation of boilers and cooling
towers, molybdenum, in the form of sodium molybdate, is used as an environmentally safe corrosion inhibitor. Sodium
molybdate is used for the manufacture of inorganic and organic pigments and as a bath additive for metal finishing. High
concentrations of molybdenum in surface waters are generally produced by industrial manufacturing processes and not due
to natural causes.
APPLICATION: Drinking and surface waters, domestic and industrial wastewater, boiler and cooling water.
RANGE: 0 – 10 ppm Molybdenum
METHOD: Molybdenum or its salts form a colored complex with Tiron at a neutral pH, the color of which
increases proportionately with the concentration of molybdenum. Sodium molybdate is
determined by multiplying the molybdenum concentration by 2.5.
SAMPLE HANDLING
& PRESERVATION: Molybdenum samples may be stored in either plastic or glass containers.
INTERFERENCES: Iron and some other cations may cause some interference with this method. To eliminate this
interference the sample must be passed through a resin column and then subjected to the
molybdenum test procedure below.
Two ready-to-use resin columns (1079) are furnished with the test kit.
CARE OF
THE RESIN
COLUMN:
Each resin column can be used for twenty water samples, after which it should be discarded. At the
conclusion of any test, the resin column should be treated with 3-4 mL of deionized water, stoppered
and capped until used again.
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