Hach DR2400 - Page 749

Sulfide
Sulfide
Sulfide_None_Other_MLB_Eng_Ody.fm Page 3 of 4
Interferences
Sample Collection, Storage, and Preservation
Collect samples in clean plastic or glass bottles. Fill completely and cap tightly.
Avoid excessive agitation or prolonged exposure to air. Analyze samples
immediately.
Method Performance
Precision
Standard: 275 µg/L S
2–
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
See Section 3.4.5 Sensitivity on page 44 for more information.
Summary of Method
Hydrogen sulfide and acid-soluble metal sulfides react with
N,N-dimethyl-p-phenylenediamine sulfate to form methylene blue. The
intensity of the blue color is proportional to the sulfide concentration. High
sulfide levels in oil field waters may be determined after proper dilution.
Test results are measured at 665 nm.
Interfering Substance Interference Levels and Treatments
Strong reducing substances
(sulfite, thiosulfate and
hydrosulfite)
Interfere by reducing the blue color or preventing its development
Sulfide, high levels
High concentrations of sulfide may inhibit full color development and require sample dilution.
Some sulfide loss may occur when the sample is diluted.
Tu rb i di ty
For turbid samples, prepare a sulfide-free blank as follows. Use it in place of the deionized water
blank in the procedure.
1. Measure 25 mL of sample into a 50-mL Erlenmeyer flask.
2. Add Bromine Water (Cat. No. 2211-20) dropwise with constant swirling until a permanent
yellow color just appears.
3. Add Phenol Solution (Cat. No. 2112-20) dropwise until the yellow color just disappears. Use
this solution to replace the deionized water in step 3 of the procedure.
Program 95% Confidence Limits of Distribution
690 256–294 µg/L S
2–
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 5 µg/L S
2–