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Molybdenum – LaMotte DC1600 Colorimeter User Manual

Page 53

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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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