LaMotte 1200 Colorimeter - Manual (Page 56)

MOLYBDENUM
TEST METHOD SPECIFICATIONS
APPLICATION
Boiler and cooling water
RANGE
0 to 30 ppm Molybdenum
METHOD
Calcium thioglycolate reacts with molybdenum to give a yellow color with an intensity
proportional to the amount of molybdenum present.
HANDLING & PRESERVATION
Molybdenum samples may be stored in either plastic or glass containers.
INTERFERENCES
Nickel levels less than 50 ppm do not interfere; aluminum levels less than 10 ppm do
not interfere; chromate, at higher concentrations, interferes due to the intense yellow
color. Ferrous iron levels below 50 ppm do not interfere, but low levels of ferric iron will
cause a large blank. Highly buffered samples may exceed the capacity of the system
possibly producing inaccurate results. Add an extra 1.0 mL of *Mo Buffer (3997) to
adjust the pH of the sample to approximately 4.5. Multiply the result in ppm by 1.08.
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06/08