EN ISO 4048:2018 PDF

Overview

EN ISO 4048:2018 - "Leather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid content" is a CEN-adopted ISO method for quantifying substances in leather that are extractable with dichloromethane and for determining the free fatty acid content of those extracts (expressed as oleic acid). The procedure applies to all types of leather and standardizes sample preparation, extraction, solvent handling and calculation of results.

Key topics and technical requirements

• Scope and applicability: Method for determining extractable matter soluble in dichloromethane and the free fatty acid content; applicable to all leather types.
• Sampling and sample prep: Refers to ISO 2418 for sampling location and ISO 4044 for grinding/preparation; samples normally analysed in duplicate.
• Extraction techniques: Two validated options
  • Soxhlet extraction (conventional solvent reflux)
  • Pressurized extraction system (accelerated/pressurized solvent extraction) Equipment providing equivalent results is permitted; temperature adjustments may be needed for high‑pressure extraction.
• Reagents and titration: Uses dichloromethane for extraction. Free fatty acids are determined after extraction using a mixed solvent (diethyl ether + 95% ethanol, neutralized) and titration with 0.1 mol/L sodium hydroxide using phenolphthalein (alternatives noted for dark solutions).
• Apparatus and conditions: Analytical balance (0.1 mg), oven at (102 ± 2) °C for drying extracts, desiccator, Soxhlet or pressurized extractor, filter thimbles, pre‑extracted cotton/wool when used.
• Results expression: Calculates mass of matter extractable in dichloromethane and free fatty acid content (as oleic acid). Annexes include comparative sample data and informative repeatability and reproducibility guidance.
• Safety note: Dichloromethane is toxic; handling and disposal instructions must be followed.

Practical applications and users

This standard is used by:

• Leather technologists and analytical chemistry laboratories for quality control and specification testing
• Tanneries and leather product manufacturers to monitor fat-liquor, waxes and non‑fat extractables
• R&D teams assessing finishing, impregnation and ageing effects on leather chemistry
• Regulatory or compliance labs assessing chemical residues and reporting free fatty acid content

Practical benefits:

• Consistent, comparable test results across suppliers and labs
• Basis for product specifications, troubleshooting processing issues (e.g., over‑oiling or impregnants) and assessing material stability

Related standards

• ISO 2418 - Leather - Sampling location
• ISO 4044 - Leather - Preparation of chemical test samples
• ISO 4684 - Leather - Determination of volatile matter
• Supersedes EN ISO 4048:2008

Keywords: EN ISO 4048:2018, dichloromethane extraction, free fatty acid, leather testing, Soxhlet, pressurized extraction, extractable substances.