Hach DR/850 Procedures Manual page 217

MANGANESE, High Range,
Method Performance
Interferences
Summary of Method
continued
e) If these increases do not occur, see Standard Additions in
Section 1 for troubleshooting information.
Standard Solution Method
Prepare a 5.0 mg/L manganese standard solution by pipetting
(use a TenSette or Class A volumetric pipet) 5.00 mL of
Manganese Standard Solution, 1000 mg/L Mn, into a 1000-mL
volumetric flask. Dilute to the mark with deionized water. Or,
prepare this standard by diluting 1.00 mL of a High Range
Manganese Standard Voluette Ampule, 250 mg/L, to
50 mL. Prepare these solutions daily. Use these solutions as the
sample in the procedure.
Precision
In a single laboratory, using a standard solution of 10.00 mg/L
Mn and two representative lots of reagent with the instrument, a
single operator obtained a standard deviation of ±0.18 mg/L Mn.
Estimated Detection Limit
The estimated detection limit for program 41 is 0.2 mg/L Mn.
For more information on the estimated detection limit, see
Section 1.
The following may interfere when present in concentrations
exceeding those listed below:
Calcium
Chloride
Iron
Magnesium
Highly buffered samples or extreme sample pH may exceed the
buffering capacity of the reagents and require sample
pretreatment; see pH Interferences in Section 1.
Manganese in the sample is oxidized to the purple permanganate
state by sodium periodate, after buffering the sample with citrate.
The purple color is directly proportional to the manganese
concentration.
217
700 mg/L
70,000 mg/L
5 mg/L
100,000 mg/L