Overview
ISO 10349-7:1992 is an international standard established by the International Organization for Standardization (ISO) that specifies test methods for determining the alkalinity or acidity of photographic-grade chemicals. This method is essential for ensuring the quality and consistency of chemicals used in photographic processes. The procedure involves a straightforward titration technique based on the dissolution of a test sample in carbon-dioxide-free water, the addition of a phenolphthalein indicator, and subsequent observation of the color change to determine if the solution is alkaline or acidic.
Key Topics
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Test Methodology
The standard describes a volumetric titration method where a weighed portion of a photographic chemical is dissolved in carbon-dioxide-free water. After adding phenolphthalein indicator:
- A pink color indicates alkalinity; titration is carried out with hydrochloric acid.
- A colorless solution indicates acidity; titration is performed with sodium hydroxide.
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Reagents
The test requires:
- Standard hydrochloric acid solution (0.01 mol/L)
- Standard sodium hydroxide solution (carbonate-free, 0.01 mol/L)
- Phenolphthalein indicator (prepared by dissolving phenolphthalein in methanol or ethanol)
- Carbon-dioxide-free water (boiled and cooled to remove dissolved CO₂)
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Calculation of Results
The alkalinity or acidity is calculated as a percentage by mass using the volume of titrant consumed, its concentration, and a defined factor related to the equivalent weight of the acid or base involved.
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Scope and Applicability
This part of the ISO 10349 series applies specifically to photographic-grade chemicals and is designed to provide precise and reproducible assessment of chemical acidity or alkalinity, critical parameters affecting photographic material performance.
Applications
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Quality Control in Photographic Chemical Production
Manufacturers of photographic-grade chemicals use ISO 10349-7 to monitor and control the acidity or alkalinity of their products to meet strict standards essential for consistent photographic processing.
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Research and Development in Photography
Laboratories developing new photographic chemicals or formulations apply this standard to characterize chemical properties accurately.
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Compliance and Certification
Ensuring conformity with international quality standards enhances market acceptance and regulatory compliance of photographic chemicals globally.
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Photographic Processing Facilities
Facilities engaged in photo development and printing may use this test method to verify chemical quality, ensuring optimal processing conditions and final image quality.
Related Standards
ISO 10349 is a multi-part series covering test methods for photographic-grade chemicals, including:
Together, these parts provide comprehensive test procedures for evaluating the quality and purity of photographic chemicals used throughout the imaging industry.
Keywords: ISO 10349-7, photographic-grade chemicals, alkalinity determination, acidity test, titration method, phenolphthalein indicator, hydrochloric acid titration, sodium hydroxide titration, photographic chemical quality, ISO standards photography, chemical analysis photography
Open preview (PDF)Photography — Photographic-grade chemicals — Test methods — Part 7: Determination of alkalinity or acidity
