An Improved Method for Accurately Determining Total Content of Four Fungicides (TCMTB, OIT, OPP And PCMC) in Leather

Abstract

Determination of total contents of four fungicides (TCMTB, OIT, OPP and PCMC) in leather is required by Ecolabels due to health risks. Thus, an improved analytical procedure based on the current Standard ISO 13365-1-2020, was investigated to accurately test the total contents of the four fungicides in leather. It was verified that the ultrasonic assisted acetonitrile extraction described in this Standard is only effective for extracting TCMTB, but inefficient for PCMC, OPP and OIT. The extraction efficiency by acetonitrile was 93% for PCMC, 95% for OPP and 89% for OIT, respectively. Methanol was proven to be an optimal alternative of acetonitrile for sample extraction and presented satisfactory extraction efficiencies (~100%) for eluting the four fungicides at a wide content range (80-470 mg/kg). The detection limits were evaluated and well satisfy the requirement by the Ecolabels. Results of HPLC chromatograms from commercial leather samples demonstrated no obvious matrix interferences from methanol extraction. Series of leather samples from different origins were analyzed. TCMTB was found in 86% and OIT in 30% of the total tested samples, which were higher in content than the allowable limits by Ecolabels.