ISO 10530:1992

Overview

ISO 10530:1992 specifies a photometric method using methylene blue for the determination of dissolved sulfide in water. The standard covers filtration and preservation, stripping of sulfide into a zinc acetate absorber, formation of leukomethylene blue and oxidation to methylene blue, and photometric measurement at 665 nm. The method is applicable to natural and waste waters requiring filtration and is designed for a mass concentration range of 0.04 mg/L to 1.5 mg/L (higher concentrations by dilution).

Keywords: ISO 10530, dissolved sulfide, methylene blue method, water quality, photometric method, 665 nm.

Key topics and requirements

• Scope and range
  • Target range: 0.04–1.5 mg/L sulfide as S (extendable by dilution).
  • Not suitable for waters that cannot be filtered as specified.
• Analytical principle
  • Filtration → conserve sulfide with ascorbate (pH 10) → strip with nitrogen → absorb into zinc acetate → react with N,N-dimethyl-p-phenylendiamine (colour-forming reagent) + ammonium iron(III) sulfate → measure absorbance at 665 nm.
• Interferences (non-significant up to stated concentrations)
  • Cyanide ≤ 2 mg/L, Iodide ≤ 20 mg/L, Thiosulfate ≤ 900 mg/L, Thiocyanate ≤ 900 mg/L, Sulfite ≤ 700 mg/L.
  • Carbon disulfide