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.
