ISO 13358:1997

Overview

ISO 13358:1997 specifies a laboratory method for the determination of easily released sulfide in water and wastewater. The procedure covers mass concentrations typically from 0.04 mg/L to 1.5 mg/L (with smaller sample aliquots enabling higher concentrations). The method stabilizes soluble sulfide with zinc acetate, strips the easily released sulfide by nitrogen gas at pH 4, and quantifies it spectrometrically after formation of methylene blue (measured at 665 nm).

Key topics and technical requirements

• Scope and range: Intended for water and wastewater; soluble sulfides fully determined, some undissolved sulfides partially determined; polysulfide and mercury sulfide limitations noted.
• Sample preservation: Add 10 mL zinc acetate to 490 mL sample, adjust pH to 8.5–9 (phenolphthalein or electrometric), refrigerate at 4 °C and analyze within 72 hours (ISO 5667-3 guidance referenced).
• Analytical principle: Nitrogen stripping of sulfide at pH 4 → capture in zinc acetate absorber → add dimethyl-p-phenylenediamine reagent and Fe(III) → formation of methylene blue → spectrometric measurement at 665 nm.
• Critical reagents and apparatus:
  • Zinc acetate stabilization solution; colour-forming reagent (N,N-dimethyl-1,4-phenylenediamine dihydrochloride in sulfuric acid); ammonium iron(III) sulfate
  • Nitrogen supply purity 99.996%, gas flow ~40 L/h, stripping time 60 min
  • Spectrometer/filter photometer with 1 cm cuvettes, pH meter, calibrated volumetric glassware
• Calibration and evaluation: Use a linear portion of a calibration curve (example range 0.2–0.7 mg/L). Calculate concentration from absorbance, blank correction and dilution factors. Report to 0.01 mg/L and up to two significant figures.
• Interferences: Specified ion limits that do not interfere (e.g., cyanide ≤2 mg/L, iodide ≤20 mg/L, thiosulfate ≤900 mg/L, thiocyanate ≤900 mg/L, sulfite ≤700 mg/L). Carbon disulfide and ethyl mercaptan thresholds also listed for spectrometric tolerance.

Applications and users

ISO 13358 is used by:

• Environmental and commercial analytical laboratories performing sulfide determination in surface water, effluent and industrial wastewater.
• Municipal and industrial water-quality monitoring and compliance testing.
• Process control labs in wastewater treatment plants and industries where sulfide monitoring guides operational decisions.

Practical uses include routine monitoring, method standardization across labs, quality assurance, and establishing calibration and reporting procedures for sulfide analysis.

Related standards

• ISO 5667-3 (sampling, preservation and handling of water samples) - referenced for sample handling.
• ISO 10530:1992 (dissolved sulfide photometric method using methylene blue) - relevant analytical background and iodometric titration guidance for standards.

Keywords: ISO 13358, water quality, determination of easily released sulfide, sulfide analysis, wastewater testing, methylene blue spectrometric method, nitrogen stripping, zinc acetate stabilization.