Overview
ISO 2480:1972 specifies a standardized gravimetric method for the determination of sulphate content in sodium chloride for industrial use. This internationally recognized standard by the International Organization for Standardization (ISO) focuses on quantifying water-soluble sulphates, ensuring the quality and consistency of industrial sodium chloride products. The method involves precipitation of sulphate ions as barium sulphate in an acidic boiling medium, followed by filtration, washing, ignition, and weighing of the resulting barium sulphate precipitate.
By providing a precise and reproducible technique, ISO 2480:1972 supports reliable chemical analysis, essential for industrial applications where sodium chloride purity impacts performance and safety.
Key Topics
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Scope of the Method
The procedure applies primarily to water-soluble sulphate present in sodium chloride and can also extend to sulphates in acid-prepared principal solutions. It mandates test portion dissolution, precipitation of sulphate ions, and gravimetric measurement.
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Analytical Principle
- Dissolution of the test sample in an acidified medium
- Precipitation of sulphate ions using barium chloride in a boiling, acidified environment
- Filtration and washing of barium sulphate precipitate to remove impurities
- Ignition of the precipitate to a constant weight
- Gravimetric determination based on the mass of barium sulphate obtained
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Reagents and Equipment
Required reagents include hydrochloric acid (~6 N), sulphuric acid (~96%), barium chloride solution (~N), silver nitrate solution for chloride detection, and nitric acid (~68%).
Necessary equipment comprises an electric furnace capable of reaching 800 ± 25°C, desiccators, platinum or porcelain crucibles, and standard laboratory apparatus.
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Special Considerations
For sulphate determinations in solutions prepared in acid media, a carefully controlled ignition and re-ignition procedure is detailed to avoid interference from sulphides or carbon.
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Calculation and Reporting
Sulphate content is calculated using a formula converting the weight of barium sulphate to sulphate percentage by mass. The test report must include the method reference, results, any anomalies, and deviations from the standard protocol.
Applications
ISO 2480:1972 is integral to industries requiring:
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Quality Control of Industrial Sodium Chloride
Accurate sulphate content determination ensures compliance with product specifications affecting downstream processes in chemical manufacturing and food processing.
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Chemical Analysis Laboratories
Standardized sulphate measurement supports consistent testing protocols, facilitating trade and regulatory adherence.
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Industrial Process Monitoring
Regular sulphate content analysis helps maintain product purity, preventing contamination-related issues in applications such as water treatment, pharmaceuticals, and textiles.
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Research and Development
Laboratories developing new sodium chloride grades or processing methods use this reliable method for evaluating sulphate impurities.
Related Standards
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ISO 2479 – Sodium chloride for industrial use - Determination of matter insoluble in water or acid, and preparation of principal solutions for analysis. This standard complements ISO 2480 by guiding the preparation of solutions used for sulphate determination.
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Other Gravimetric Analysis Standards – ISO maintains various standards dealing with gravimetric and volumetric analysis applicable to inorganic salt determination, supporting broader chemical quality assessments.
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Chemical Reagent Standards – Specifications for reagents such as barium chloride and acids used ensure reagents meet purity requirements for accurate sulphate testing.
Keywords: ISO 2480, sodium chloride analysis, sulphate content determination, barium sulphate gravimetric method, industrial sodium chloride, chemical analysis standards, gravimetric analysis, sulphate gravimetric method, ISO standards for sodium chloride, industrial salt quality control