Overview
EN ISO 17489:2013 / ISO 17489:2013 - Leather - Chemical tests - Determination of tan content in synthetic tanning agents - specifies a simple, practical laboratory method to determine the adsorbable (tan) fraction of synthetic tanning agents using a polymer-based adsorbent. Developed by IULTCS in collaboration with CEN/TC 289, this standard is optimized for routine quality control and batch-to-batch consistency checks in the manufacture of synthetic tanning agents.
Key topics and technical requirements
- Scope and principle
- Measures the adsorbable fraction (tan content) by comparing dry residue before and after adsorption onto an insoluble crosslinked vinylimidazole/vinylpyrrolidone copolymer.
- Acidified tanning solution (pH 2.0–2.3) is mixed with the polymer; the polymer adsorbs polyphenolic tanning components. The decrease in dry content equals the tan content.
- Required reagents and materials
- Crosslinked insoluble vinylimidazole/vinylpyrrolidone copolymer (adsorbent)
- 50% formic acid, gelatin, sodium chloride, and deionized/distilled water (ISO 3696 compliance)
- Apparatus and conditions
- Analytical balance (±0.1 mg), ventilated drying oven (105 °C ±2 °C), magnetic stirrer, pH meter, stainless steel evaporating dishes, membrane filters (0.45 µm)
- Procedure highlights
- Prepare duplicate tanning solutions (specified mass ranges for powder and liquid agents), adjust pH, dilute to volume.
- Determine total dry content by evaporating 50 ml aliquots to constant mass at 105 °C.
- Adsorption step: mix ~40 g polymer with 300 g tanning solution, stir ~30 min, settle ~90 min, filter and confirm absence of tanning agent in filtrate via a gelatin/NaCl turbidity test.
- Calculate tan content as the difference between initial and post-adsorption dry residues.
- Quality and reproducibility
- Designed for routine QC; interlaboratory trials indicate improved repeatability over traditional hide-powder methods (see Annex A for trial results).
Applications and users
- Primary users
- Manufacturers of synthetic tanning agents conducting production quality control and batch verification.
- Leather chemists and testing laboratories performing routine chemical tests on tanning formulations.
- R&D teams evaluating formulation changes or raw-material variability.
- Practical benefits
- Faster and more reproducible than hide-powder adsorption methods; suitable for on-site production testing.
- Enables consistent monitoring of tanning strength and process control during manufacture.
Related standards
- ISO 14088 - Traditional hide-powder adsorption method for tanning component determination (results are substrate-specific and not directly comparable to ISO 17489).
- ISO 3696 - Water for analytical laboratory use (referenced for water quality in this method).
Keywords: EN ISO 17489:2013, ISO 17489:2013, leather chemical tests, tan content, synthetic tanning agents, polymer-based copolymer, vinylimidazole vinylpyrrolidone, batch-to-batch consistency, quality control.