Highly sensitive flow injection analysis of lipid hydroperoxides in foodstuffs

Lipid hydroperoxides in oils and foods were measured by a flow injection analysis system with high sensitivity and selectivity. After sample injection, lipid hydroperoxides were reacted with diphenyl-1-pyrenylphosphine (DPPP) in a stainless steel coil, then the fluorescence intensity of DPPP oxide, that was produced by the reaction, was monitored. By this method, trilinolein hydroperoxide showed good linearity between 0.4 and 79 pmol and their detection limits were 0.2 pmol (signal-to-noise ratio=3). The method made it possible to inject samples at 2-min intervals. There was a good agreement of the amounts of lipid hydroperoxides in oils and foods between by the batch method with DPPP and by the proposed method (coefficient of correlation: r=0.999; n=21; peroxide value=0.09-167 meq/g). With this method, the calibration graph of trilinolein hydroperoxide was useful for all samples tested.