Hach Pocket Colorimeter II Instruction Manuals page 62

Chlorine Dioxide,
Because chlorine dioxide is difficult and hazardous to produce, check the DPD and
Glycine Reagents by using chlorine standards. Proceed as follows:
1. Prepare a 1-mg/L free chlorine standard.
a. Obtain Free Chlorine Standards (Cat. No. 14268-10).
b. Determine the concentration of the standard from the certificate of analysis
shipped with the standard (50–75 mg/L Cl
needed as follows:
mL standard needed = 100
c. Pipet the volume of standard needed into a 100-mL volumetric flask. Dilute to
the line with chlorine demand-free deionized water. Invert to mix.
2. Perform the chlorine dioxide test on the standard without adding Glycine Reagent
(step 3 of the procedures).
3. The chlorine dioxide reading should be 2.4 times greater than the chlorine
concentration. If so, this verifies that the DPD Reagent and the instrument are
working properly.
continued
÷
standard concentration
1—62
). Calculate the volume of standard
2