Overview
ISO 10349-6:1992 - Photography - Photographic-grade chemicals - Test methods - Part 6: Determination of halide content - specifies a comparative turbidity test for measuring halide content (reported as chloride ions, Cl–) in photographic-grade chemicals. Published by ISO/TC 42 (Photography) in 1992, the method uses a weighed test portion, dissolution in water, controlled acidification and precipitation with silver nitrate, and visual comparison of turbidity in matched Nessler colour‑comparison cylinders against prepared halide standards.
Key topics and requirements
- Scope: General test method for halide content of photographic-grade chemicals; results reported as chloride ions (Cl–). Individual standards may report halide as a salt by modifying the calculation.
- Sample preparation: Weigh a test portion (0.9–1.1 g), dissolve in 200 ml water and take a 20 ml aliquot.
- Standards: Two halide standard solutions are defined:
- Halide standard A: 0.01 mg Cl/ml (prepared from sodium chloride stock)
- Halide standard B: 0.001 mg Cl/ml (diluted from stock)
- Reagents:
- Nitric acid solution (1 + 9)
- Silver nitrate solution, 100 g/l
- Procedure: Add the appropriate volume of halide standard A or B (per Table 1 test limits) to a second beaker; to both sample and standard add nitric acid and silver nitrate, dilute to 50 ml, transfer to 50 ml matched Nessler cylinders and compare turbidity visually. The turbidity in the test solution shall not exceed that of the applicable standard.
- Apparatus: Two matched Nessler colour‑comparison cylinders (50 ml).
- Hazards and reporting: Follow ISO 10349-1 for general hazard warnings and reporting requirements. Test report must identify the method, operating details, any deviations and the result.
Applications and users
- Quality control laboratories in photographic chemical manufacturing
- Analytical/contract testing labs performing routine acceptance tests
- Suppliers and purchasers of photographic reagents who require specification compliance
- Standards and regulatory bodies assessing material conformity
Benefits include a simple, low‑instrumentation visual method for ensuring halide impurities are within acceptable limits for photographic processes where halides can affect image formation or processing chemistry.
Related standards
ISO 10349 is a multipart series for photographic‑grade chemical testing. Relevant parts include:
- ISO 10349-1: General requirements
- ISO 10349-2 to -12: Tests for insoluble matter, residue after ignition, heavy metals, alkalinity/acidity, volatile matter, sulfide content, specific gravity and density, etc.
Keywords: ISO 10349-6, halide content, photographic-grade chemicals, test methods, silver nitrate, Nessler cylinders, chloride determination.
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