Hach POCKET COLORIMETER II, Instruction Manuals

Page: 64 / 116

1—64
Chlorine Dioxide,
continued
In addition, a user-generated calibration curve can be made and programmed into the
Pocket Colorimeter™ II. See
User-Entered Calibration on page 2—15 .
Method Performance
Typical Precision (95% confidence interval):
4.78 ± 0.22 mg/L ClO
2
(AccuVac)
2.08 ± 0.04 mg/L ClO
2
(Powder Pillows)
Estimated Detection Limit:
EDL = 0.04 mg/L ClO
2
(AccuVac and Powder Pillows)
Interferences
Samples containing more than 250 mg/L alkalinity or 150 mg/L acidity as CaCO
3
may
inhibit full color development, or the color may fade instantly. Neutralize these
samples to pH 6–7 with 1 N Sulfuric Acid Standard Solution or 1 N Sodium Hydroxide
Standard Solution. Determine the amount required on a separate 10-mL sample. Add
the same amount to the sample to be tested. Correct for the additional volume.