1—32
Chlorine, Free and Total, LR, continued
Accuracy Check
Standard Additions Method
1. Use the ampule breaker to snap the neck off a low range Chlorine
Standard Solution Ampule, 20–30 mg/L Cl
2
.
2. Use a TenSette® pipet to add 0.1, 0.2, and 0.3 mL of standard to three
10-mL samples. Swirl gently to mix. (For AccuVac Ampules, use 0.2, 0.4,
and 0.6 mL of standard and a 25-mL sample in a 50-mL beaker.)
3. Analyze a 10-mL aliquot of each sample as described in the procedure.
Each 0.1 mL of standard will cause an incremental increase in chlorine.
The exact value depends on the concentration of the ampule standard.
Check the certificate enclosed with the ampules for the chlorine
concentration and calculation of the expected chlorine increase.
Standard Solution Method
Standard solutions for chlorine are difficult and time-consuming to prepare.
Errors can occur if attention to detail is not addressed during preparation of the
standards. The calibration curve is prepared under rigorous analytical
laboratory conditions. Use the factory calibration for most normal testing.
5957088.book Page 32 Friday, March 22, 2013 3:54 PM
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