International Organization for Standardization

Water Quality - Determination of Dissolved Sulfide - Photometric Method Using Methylene Blue First Edition
 N 10530

Annotation

Application range

This International Standard specifies a photometric method for the determination of dissolved sulfide in water. The method is applicable to the determination of dissolved sulfide in a mass concentration range from 0,04 mg/l to I,5 mg/l.

Higher concentrations may be determined by reducing and subsequently diluting the volume of the water sample used.

The method is applicable to waste water and natural waters requiring filtration.

Interferences

The following ions do not interfere with the method as long as the mass concentrations specified below are not reached or exceeded:

Cyanide 2 m/l

Iodide 20 mg/l

Thiosulfate 900 mg/l

Thiocyanate 900 mg/l

Sulfite 700 mg/l

When applying this procedure, the determination of the sulfide portion from polysulfides will be incomplete.

Mass concentrations of carbon disulfide < 10 mg/l and/or ethyl mercaptan < 1 n J/I do not interfere with the method.

Waters which are not filterable according to clause 6 cannot be analysed by this method. In those cases sulfide which is easily liberated at pH 4 is determined. (An International Standard covering this is being prepared.)