Hach DR2400 Manual page 749

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Table of Contents

Interferences

Interfering Substance

Strong reducing substances

(sulfite, thiosulfate and

hydrosulfite)

Sulfide, high levels

Sample Collection, Storage, and Preservation

Method Performance

Summary of Method

Sulfide_None_Other_MLB_Eng_Ody.fm

Interfere by reducing the blue color or preventing its development

High concentrations of sulfide may inhibit full color development and require sample dilution.

Some sulfide loss may occur when the sample is diluted.

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.

Collect samples in clean plastic or glass bottles. Fill completely and cap tightly.

Avoid excessive agitation or prolonged exposure to air. Analyze samples

immediately.

Standard: 275 µg/L S

See Section 3.4.3 Precision on page 44 for more information, or if the standard

concentration did not fall within the specified range.

Portion of Curve

Entire range

See Section 3.4.5 Sensitivity on page 44 for more information.

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.

Interference Levels and Treatments

95% Confidence Limits of Distribution

256–294 µg/L S

∆Concentration