Simultaneous stopped-flow determination of butylated hydroxyanisole and propyl gallate using a T-format luminescence spectrometer

A simple and fast luminescent method is used for the first time to resolve a mixture of two synthetic antioxidant;s, propyl gallate (PG) and butylated hydroxyanisole (BHA), by the joint use of the stopped flow mixing techniqu e and a T-format luminescence spectrometer. The determination of these comp ounds involves two different and independent reactions. On the one hand, PG determination is based on an energy transfer process that involves the for mation of a lanthanide chelate with terbium in the presence of Triton X-100 and tri-n-octylphosphine oxide. On the other hand, BHA is determined using a reaction between the oxidized form of Nile Blue and the antioxidant. Bot h systems are excited at the same excitation wavelength (310 nm), and the e mission wavelengths are 545 and 665 nm for PG and BHA, respectively. The ab sence of overlap in the emission spectra makes it possible to measure separ ately the analytes in each channel of the instrument. Initial rate and equi librium signal are used as analytical parameters and measured in 0.1 and 1 s for PG and BHA, respectively. Calibration graphs are linear over the rang e 0.09-3.5 mu g mL(-1) for PG and 0.3-15 mu g mL(-1) for BHA. The relative standard deviations of both systems are close to 2%. The proposed method is applied to the determination of these two antioxidants in several commerci al food samples with recoveries ranging between 94.8 and 102.98 for PG and between 94.1 and 102.1% for BHA.