Efficient flow injection and sequential injection methods for spectrophotometric determination of oxybenzone in sunscreens based on reaction with Ni(II)

Spectrophotometric determination of a widely used UV-filter, such as oxybenzone? is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative put-poses. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC, Data show that both Fl and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LOB are adequate to the analysis requirements. The sample frequency obtained by Fl is three-fold higher than that of SI analysis. SI is less reagent-consuming than FI.