Determination of hydrogen peroxide in commercial glycerin using electron spin resonance and chemiluminescence assay

Glycerin is widely used in pharmaceuticals, cosmetics, and foods. In recent years, it has been mainly derived from plant-based materials, particularly palm oil. The most abundant polyphenol in palm oil is 3-O-caffeoylshikimic acid (CSA). Polyphenols reportedly react with oxygen to generate hydrogen peroxide (H₂O₂). In this study, we investigated the generation of H₂O₂ from CSA and palm-derived glycerin using the bis(2,4,6-trichlorophenyl)oxalate (TCPO) chemiluminescence method and electron spin resonance spectroscopy. H₂O₂ concentrations in the range of 10^-4 to 10^-6 mol/L were detected in commercial glycerin samples. In addition, the H₂O₂ concentrations in a commercial glycerin varied widely between batches, even among samples of glycerin produced by the same company. However, the concentrations were approximately 1/1000 of that permitted in disinfectants used in pharmaceuticals, indicating extremely low biological toxicity. Furthermore, the TCPO chemiluminescence method proved to be highly sensitive and precise, even in viscous glycerin samples, showing potential for application in quality control of glycerin formulations and related industrial products.