Molybdenum, Molybdate
Molybdenum, Molybdate
Molybdenum_PP_Low_TER_Eng_Ody.fm Page 3 of 6
Highly buffered samples or extreme sample pH may exceed the buffering
capacity of the reagent and require sample pretreatment. Adjust the sample pH
to between 3–5 by adding, dropwise, an appropriate amount of acid or base such
as 1.0 N Sulfuric Acid Standard Solution (Cat. No. 1270-32), or 1.0 N Sodium
Hydroxide Standard Solution (Cat. No. 1045-32). If significant volumes of acid or
base are used, a volume correction should be made by dividing the total volume
(sample + acid + base) by the original volume and multiplying the test result by
this factor.
After a number of samples have been analyzed, the sample cells may exhibit a
slight blueish discoloration. Rinse the cells with 1:1 Hydrochloric Acid Solution
(Cat. No. 884-49) to eliminate this build-up.
Sulfite Greater than 6500 mg/L
* Read the molybdenum concentration immediately after the beep of the 2-minute reaction period.
Table 2 Substances that Cause a Positive Interference
Interfering Substance Interference Levels and Treatments
Benzotriazole Greater than 210 mg/L
Carbonate Greater than 1325 mg/L
Morpholine Greater than 6 mg/L
Phosphonate HEDP
Positive interference of about 10% up to 30 mg/L. As the concentration increases above
30 mg/L, a decrease in the molybdenum concentration reading occurs (negative interference).
Silica Greater than 600 mg/L
Table 1 Substances that Cause a Negative Interference (continued)
Interfering Substance Interference Levels and Treatments
Table 3 Non-Interfering Substances
Substance Highest Concentration Tested
Bisulfite 9600 mg/L
Calcium 720 mg/L
Chlorine 7.5 mg/L
Magnesium 8000 mg/L
Manganese 1600 mg/L
Nickel 250 mg/L
PBTC (phosphonate) 500 mg/L
Sulfate 12,800 mg/L
Zinc 400 mg/L
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