Direct measurement of lipid peroxidation in oil-in-water emulsions using multiwavelength derivative UV-spectroscopy

Using second-derivative multiwavelength UV-spectral data (200-300 nm), it was possible to measure lipid peroxidation in oil-in-water lipid emulsions using a multivariate calibration method (partial least squares regression). For a linoleic acid emulsion (0.42 mM in phosphate buffer, pH 5.5-7.0), with metmyoglobin or ferrylmyoglobin as initiator, conjugated dienes could not be quantified by direct single-wavelength absorption spectroscopy (234, 244, or 280 nm) when compared to a reference method based on ether extraction and second-derivative spectroscopy at 234 nm. Direct multi-wavelength absorption (200-300 nm) and second-derivative methods (234, 244, 280 nm, and 200-300 nm) provided superior results with high correlation coefficients (r ranged from 0.78 to 0.98) when compared to the standard extraction method. The multiwavelength second-derivative method (200-300 nm) gave the highest correlation and is recommended for on-line control of lipid peroxidation in heterogeneous systems.