Overview
ISO 10349-5:1992 - Photography - Photographic‑grade chemicals - Test methods - Part 5: Determination of heavy metals and iron content - specifies a visual colour‑comparison procedure for detecting and limiting heavy metals (expressed as Pb) and iron in photographic‑grade chemicals. The method uses prepared test samples and standard solutions, preconditioning, chemical reagents (sodium sulfide for heavy metals; 1,10‑phenanthroline for iron), dilution to volume, and comparison in paired Nessler colour‑comparison cylinders (or optionally by spectrometer).
Key topics and requirements
- Scope: General test method for heavy metals and/or iron content in photographic chemicals; refer to ISO 10349‑1 for hazard codes and general requirements.
- Standards and reagents: Preparation of heavy‑metals standard (0.010 mg Pb/ml from lead acetate trihydrate) and iron standard (0.010 mg Fe/ml from ferrous ammonium sulfate) as defined in the standard.
- Sample preparation options: Residue after ignition, dilution with water, or dilution following acid treatment (clauses 7.1–7.3).
- Preconditioning: p‑nitrophenol indicator used to adjust pH to neutral range before reagent addition; specific acid/base adjustments described in the text.
- Analytical reactions:
- Heavy metals: addition of sodium sulfide produces a colour for comparison.
- Iron: addition of 1,10‑phenanthroline reagent produces an orange complex for comparison.
- Measurement: Transfer preconditioned test and standard solutions to matched Nessler cylinders (50 ml) and compare visually. Any colour in the test solution must not exceed that of the corresponding standard. Colour comparisons may be made with a spectrometer for greater objectivity.
- Reporting: Specify the method variant used, test result, and any non‑standard operating details or incidents that could affect results.
Applications and users
- Quality control and incoming inspection of photographic‑grade chemicals (developers, fixers, toners, etc.)
- Chemical manufacturers and suppliers ensuring product compliance with photographic purity requirements
- Analytical and photographic testing laboratories performing acceptance testing and routine monitoring
- Conservators and archival labs concerned with contamination risks from heavy metals or iron in processing chemicals
Related standards
- ISO 10349‑1:1992 - General requirements and hazard codes for ISO 10349 test methods
- ISO 10349 other parts (e.g., Part 4: Determination of residue after ignition) which provide complementary sample‑preparation procedures referenced by Part 5
Keywords: ISO 10349-5, photographic‑grade chemicals, heavy metals determination, iron content, Nessler colour‑comparison cylinders, sodium sulfide, 1,10‑phenanthroline, photographic chemical testing.
Open preview (PDF)Photography — Photographic-grade chemicals — Test methods — Part 5: Determination of heavy metals and iron content
