Chemical Determination of Total Metal Content in Leather according to ISO 17072-2:2022

This standard specifies a method for determining the total content of specific metals (such as chromium, lead, arsenic, cadmium, etc.) in leather. It involves the complete breakdown (digestion) of the leather sample to release all bound metals into solution. The metals are then quantified using atomic spectrometric techniques, such as:

• Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or
• Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or
• Atomic Absorption Spectrometry (AAS)

This method determines the total metal content, not just extractable (soluble) forms.

1. Sample Preparation

• A representative leather sample is cut and dried.
• The sample is ground or shredded to increase the surface area.
• A precise mass (usually 0.5 to 1.0 g) is weighed.

2. Digestion

• The sample is digested using a mixture of acids, typically nitric acid (HNO₃), possibly combined with hydrogen peroxide (H₂O₂) or hydrochloric acid (HCl).
• Digestion is carried out in a microwave digestion system or heating block until complete dissolution of organic material.

3. Analysis

• The digested solution is diluted to a known volume with deionized water.
• Metal concentrations are determined using:
  • ICP-OES, ICP-MS, or AAS, depending on the required sensitivity and metal type.
• Calibration is done using standard solutions of known metal concentrations.

4. Quality Control

• Use of blank samples, standard reference materials, and recovery checks is recommended to ensure reliability.

• Results are expressed in mg/kg of dry leather.
• Both individual metal concentrations and total metal content can be reported