Overview
SIST ISO 5517:1995 specifies a standardized photometric method for the determination of iron content in fruits, vegetables, and derived products. This standard utilizes the 1,10-phenanthroline method, offering a reliable, accurate, and reproducible approach to quantify trace iron in agricultural food products. The process includes decomposition of organic matter, reduction of ferric (Fe³⁺) to ferrous (Fe²⁺) iron, formation of a red-colored stable complex with 1,10-phenanthroline under buffered conditions, and measurement of absorbance at 508 nm using a spectrophotometer. Compliance with this internationally recognized method supports food quality control, nutritional labeling, and regulatory requirements.
Key Topics
- Sample Preparation: Details on selecting and preparing test portions either by weight or volume, ensuring representative results for fruits, vegetables, and processed products.
- Decomposition Methods: Integration with ISO 5515 (wet decomposition) or ISO 5516 (ashing) for breaking down organic matter before analysis.
- Reagent Requirements: Use of specific analytical-grade chemicals such as hydroxylammonium chloride, 1,10-phenanthroline, and various acids.
- Photometric Measurement: Formation of Fe(II)-phenanthroline complex in buffered media and absorbance readings at 508 nm for precise quantification.
- Calibration and Repeatability: Procedures for blank testing, calibration curve preparation using standard iron solutions, and criteria for acceptable repeatability between duplicate tests.
- Reporting: Requirements for documenting methodology, findings, and any deviations, ensuring traceability and reproducibility.
Applications
Food Quality Control
- Nutritional Labeling: Ensures accurate reporting of iron content in compliance with local and international food labeling regulations.
- Product Development: Assists manufacturers in verifying iron fortification levels and evaluating natural content in fruits, vegetables, and derived goods.
- Regulatory Compliance: Supports adherence to food safety standards and import/export regulations by delivering validated test results.
- Research and Development: Provides standardized data for scientific studies, nutritional surveys, and quality assurance programs.
Laboratory and Industry Use
- Analytical Laboratories: Delivers a repeatable, reliable protocol that aligns with international best practices for food analysis.
- Food Processing Companies: Enables process control and monitoring of iron content during manufacturing and product refinement.
- Agriculture Sector: Assists growers and suppliers in assessing nutritional value and iron levels in fresh produce.
Related Standards
- ISO 5515: Fruits, vegetables, and derived products - Decomposition of organic matter - Wet method. Used for initial sample digestion.
- ISO 5516: Fruits, vegetables, and derived products - Decomposition of organic matter - Ashing method. Alternative approach for sample preparation.
- ISO 648: Laboratory glassware - One-mark pipettes. Specifies requirements for precision in volumetric measurements.
- ISO 1042: Laboratory glassware - One-mark volumetric flasks. Ensures accuracy in dilution and standard preparation.
- ISO/R 385: Burettes. Sets criteria for accurate titration, essential for reagent measurements in the photometric method.
Keywords: iron content determination, photometric analysis, 1,10-phenanthroline, fruits and vegetables, food quality control, ISO 5517, food safety standards, laboratory methods, iron quantification, agricultural food products, SIST standards.