ISO 2461:1973

Overview

ISO 2461:1973 specifies a standardized chemical analysis method for determining matter insoluble in water in sodium chlorate intended for industrial use. The method applies to samples where the insoluble fraction is greater than 0.01% (m/m) and is intended for pure sodium chlorate products - it is not applicable to formulated mixtures such as herbicides or insecticides. The procedure is based on dissolving a test portion in water, filtering the solution, and quantifying the dried residue retained on a filter crucible.

Key Topics and Requirements

• Field of application: Designed for sodium chlorate for industrial use; applicable when insoluble matter > 0.01% (m/m).
• Safety note: Sodium chlorate is an oxidizer and can induce combustion. Avoid heat sources and contact with combustible materials; wash spills with copious water.
• Apparatus:
  • 250 ml conical flask with ground-glass stopper
  • Sintered-glass filter crucible, porosity grade P40 (pore size ~16–40 µm)
  • Vacuum filtration setup and desiccator
  • Electric oven controllable at 105 ± 2 °C
• Reagent: Distilled water or equivalent purity
• Test portion and solution:
  • Typical test portion: about 20 g (weighed to 0.1 g)
  • Dissolve in 200 ml water and shake for 10 minutes
• Filtration and washing:
  • Filter under vacuum through the preweighed sintered crucible
  • Wash the retained insoluble matter four times using 25 ml water each time, keeping the filter as dry as possible between washes
• Drying and weighing:
  • Dry the filter crucible at 105 ± 2 °C (oven) - typically 1 hour, cool in a desiccator and weigh
• Result expression:
  • Insoluble matter is reported as percentage by mass (based on the test portion mass and filter crucible weight change)
  • Results are reported to two decimal places
• Documentation: Test report must include method reference, results with expression method, and any unusual observations.

Applications and Users

• Quality control and analytical laboratories in sodium chlorate production
• Industrial chemical manufacturers and suppliers for batch release and specification compliance
• Regulatory and inspection bodies assessing product purity and contaminant levels
• Procurement teams and technical buyers verifying supplier certificates

Practical uses include routine quality checks, troubleshooting production contamination, acceptance testing of incoming material, and supporting safety and handling decisions.

Related Standards

• Developed by ISO Technical Committee ISO/TC 47 (Chemistry).
• For broader context, consult ISO standards and national methods on chemical analysis, purity testing, and safety of industrial oxidizers.