Hach POCKET COLORIMETER II Instruction Manual page 34

Fluoride, AccuVac® Method,
Alkalinity (as CaCO
Aluminum
Chloride
Iron, ferric
Phosphate, ortho
Sodium Hexametaphosphate
Sulfate
SPADNS Reagent contains enough arsenite to eliminate interference from up to
5 mg/L chlorine. For higher chlorine concentrations, add 1 drop of Sodium
Arsenite Solution to 25 mL of sample for each additional 2 mg/L of chlorine.
To check for interference from aluminum, read the concentration 1 minute after
mixing the reagent solution (step 4), then again after 15 minutes. An appreciable
increase in concentration suggests aluminum interference. Waiting 2 hours before
making the final reading will eliminate the effect of up to 3.0 mg/L aluminum.
)
3
continued
Concentration
5000 mg/L
0.1 mg/L
7000 mg/L
10 mg/L
16 mg/L
1.0 mg/L
200 mg/L
1—34
–
Error (mg/L F )
–0.1
-0.1
+0.1
-0.1
+0.1
+0.1
+0.1