Abstract

The topic of chromium (VI) in leather has been debated by the whole supply chain for years. Its significance has recently been raised due to release of a consultation document by the European Chemicals Agency on skin sensitising substances, in which it was proposed that the acceptable Cr(VI) concentrations in leather goods should be lowered from 3ppm to 1ppm. The proposition of a stricter limit and analytical difficulties at the current 3ppm compliance limit advocate the need for a review of current standards.

Recent research by the Institute for Creative Leather Technologies (ICLT) has investigated both the colorimetric (Part 1) and chromatographic (Part 2) methods under BS EN ISO 17075. The focus of the study was to identify possible sources of interference leading to false results, and calculate the limit of quantification with respect to the proposed new compliance limit.

Studies into the colorimetric method have shown the presence of Cr(III), dyes and proteins can be significant interferences becoming critical at low Cr(VI) concentrations. Dilution factors lead to the detection of < 1μM Cr(VI) in solution and BS EN ISO 17075-1 were concluded to be not capable of resolving to 3ppm or 1ppm in leather. Possible improvements to test methods are discussed although these would still not allow a 1ppm detection. It is suggested the ion-chromatographic (IC) aspect of BS EN ISO 17075-2 should be coupled to an inductively coupled plasma (ICP) ionisation system with mass spectrometry (MS) detector to enhance detection limits.