Sampling And Storage; Accuracy Check - Hach POCKET COLORIMETER II Instruction Manual

Fluoride, AccuVac® Method,

Sampling and Storage

Samples may be stored in glass or plastic bottles for at least 7 days when cooled to 4 °C
(39 °F) or lower. Warm samples to room temperature before analysis.

Accuracy Check

Standard Solutions Method
Use a 1.00 mg/L fluoride standard solution in place of the sample. Perform the
procedure as described above.
A variety of standard solutions covering the entire range of the test is available from
Hach. Use these in place of the sample to verify technique.
Note:
Minor variations between lots of reagent become measurable above 1.5 mg/L. While results in
this region are usable for most purposes, better accuracy may be obtained by diluting a fresh
sample 1:1 with deionized water and re-testing. Multiply the result by 2.
Multiparameter standards that simulate typical drinking water concentrations without
dilution are available to confirm test results. See
continued
Optional Reagents on page
1—30
1—37.