Flow injection-chemiluminescence determination of octyl dimethyl PABA in sunscreen formulations Original Research Article

A sensitive flow injection (FI) procedure was developed for the determination of the UV-filter octyl dimethyl PABA in sunscreen formulations based on its chemiluminescence (CL) induced by potassium permanganate in sulfuric acid. Both second-order and log–log calibration graphs can be used to perform the analysis. Ninety injections per hour can be carried out, which means a sample throughput of 18 h−1 if five injections per solution are performed. The limit of detection (3σ) was 25 ng ml−1. The interference effects of the excipient and other UV filters are studied. Sunscreen formulations containing octyl dimethyl PABA were analysed by both the proposed FI-CL method and a liquid chromatography reference method. The two methods gave comparable results.