LaMotte DC1600 Colorimeter - Manual (Page 39)

FLUORIDE
SPADNS CODE 3647
QUANTITY CONTENTS CODE
2 x 60 mL *Acid-Zirconyl-SPADNS Reagent *3875-H
60 mL *Sodium Arsenite Solution *4128-H
1 Pipet, 0.5 mL, plastic 0353
1 Pipet, 1.0 mL, plastic 0354
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are supplied for
these reagents. For your safety, read label and accompanying MSDS before using.
Fluoride may occur naturally in some ground waters or it may be added to public drinking water supplies to maintain a 1.0
mg/L concentration to prevent dental cavities. At higher concentrations, fluoride may produce an objectionable
discoloration of tooth enamel called fluorosis, though levels up to 8 mg/L have not been found to be physiologically
harmful.
APPLICATION Drinking and surface waters; domestic and industrial waters.
RANGE: 0.0 – 2.0 ppm Fluoride
METHOD: Colorimetric test based upon the reaction between fluoride and zirconium dye lake. The
fluoride reacts with the dye lake, dissociating a portion of it into a colorless complex ion and
dye. As the fluoride concentration increases, the color produced becomes progressively lighter.
SAMPLE HANDLING
& PRESERVATION: Samples may be stored and refrigerated in plastic containers.
INTERFERENCES: The following substances produce a positive interference at the concentration given:
Chloride (Cl
–
) 7000 mg/L
Phosphate (PO
4
–3) 16 mg/L
Sulfate (SO
4
–2) 200 mg/L
The following substances produce a negative interference at the concentration given:
Alkalinity (CaCO
3
) 5000 mg/L
Aluminum (Al
3+
) 0.1 mg/L
Iron (Fe
3+
) 10 mg/L
Color and turbidity must be removed or compensated for in the procedure. Temperature should be maintained within 5°C
of room temperature.
NOTE: This procedure uses the EPA approved SPADNS Reagent System for fluoride found in method 4500-F-D, 17th
Edition of Standard Methods, page 4-89.
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