Resonance light-scattering method for the determination of labetalol using uranyl acetate and aniline blue

A sensitive and convenient method for determining labetalol has been developed based on resonance light-scattering using ternary complex of aniline blue (AB), uranyl ion (UO22+) and labetalol. At pH 6.0-7.0, labetalol reacted with AB and UO22+ to form an ion-association complex that resulted in considerable resonance light-scattering (RLS) characterized with a peak at 356 nm. The RLS was successfully applied to the determination of labetalol. The intensity of RLS (IRLS) at 356 nm linearly depended on the concentration of labetalol ranging from 4.0 × 10− 7 to 2.4 × 10− 4 mol L− 1. The lower detection limit was 2.1 × 10− 7 mol L− 1. The present method is highly selective to labetalol and can successfully be applied to the determination of labetalol in human urine.