ISO 17075-1:2017

Overview

ISO 17075-1:2017 - Leather - Chemical determination of chromium(VI) content in leather - Part 1: Colorimetric method defines a laboratory procedure to quantify extractable chromium(VI) in leather. The standard specifies a colorimetric assay based on 1,5‑diphenylcarbazide (DPC) that yields a red/violet complex measured photometrically at 540 nm, and is suitable for results down to 3 mg/kg (expressed on dry mass). The method is applicable to all leather types and stresses that extraction conditions (solution, pH, time) directly determine reported values.

Key topics and requirements

• Extraction conditions: Leaching of chromium(VI) is carried out in a phosphate buffer at pH 7.0–8.0 under defined degassed conditions (argon or nitrogen) - results are strictly dependent on these parameters.
• Sample prep and mass: Typical analytical sample ≈ 2 g cut to small pieces (ISO 4044 referenced); extraction performed with mechanical shaking (≈ 3 h at ~100 min‑1).
• Colorimetric reaction: Chromium(VI) oxidizes DPC to form a colored complex measured at 540 nm; absorbance is used for quantification.
• Interference control: Co‑extracted dyes and coloured substances can be removed using solid phase extraction (SPE) cartridges (e.g., RP C18 or activated magnesium silicate) prior to colorimetric analysis.
• Calibration and standards: The standard provides procedures for preparing calibration and stock solutions (potassium dichromate used as a chromium(VI) standard).
• Detection limit and comparability: Method quantifies down to 3 mg/kg; results are not comparable with other extraction procedures unless those follow the same conditions. If both ISO 17075‑1 and ISO 17075‑2 are used, ISO 17075‑2 (ion chromatography) is considered the reference method.
• Quality controls: Blank, calibration, and recovery checks (including matrix and SPE influences) are required.

Applications and users

ISO 17075-1:2017 is used for:

• Leather manufacturers and finishers for in‑house quality control.
• Independent testing laboratories performing compositional analysis.
• Product compliance and safety teams assessing chromium(VI) content in leather goods.
• Material scientists and R&D evaluating tanning processes and mitigation measures. Practical uses include batch release testing, supplier verification, and investigation of colored/leather treated materials where a colorimetric approach is suitable.

Related standards

• ISO 17075-2 - Ionic chromatography method (reference method; fewer color interferences).
• ISO 2418 - Sampling location for leather testing.
• ISO 4044:2017 - Preparation of chemical test samples.
• ISO 3696 - Water for analytical use.

Keywords: ISO 17075-1:2017, chromium(VI) in leather, colorimetric method, leather testing, solid phase extraction, diphenylcarbazide, photometric detection, pH 7–8, limit of quantification 3 mg/kg.