Direct parallel flow injection multichannel spectrophotometric determination of olive oil peroxide value

An automated parallel flow injection (PA-FI) spectrophotometric method for the determination of peroxide value (PV, meg O-2 kg(-1) oil) in olive oil is described. A home-made PA-FI analyser incorporating 10 incubation coils and using flow reversals achieves a sampling rate of 83 samples h(-1) while each sample is incubated for 5 min. Detection is achieved by monitoring iodine liberated from NaI by lipid peroxides at 360 nm. The new PA-FI method allows olive oil analysis without pretreatment or dilution and minimizes solvent consumption (2.0 mi of acetic acid and 3.4 mi of n-propanol per analysis). Precision was found to be better than 2.0% relative standard deviation (n=10). The linear range was 2.5-80 PV, rendering the method useful for the analysis of edible olive oils. Results obtained by the proposed method compare well (0-5.6% relative difference, mean 1.0%) with those obtained by an official method that is time-consuming and uses large amounts of organic solvents. The PA-FI analyser developed allows automation of methods that require long incubation times without loss of sampling rate. Up to 60 samples h(-1) can be analysed when 10 min incubation time is required. The detector is inserted in the flow path before the incubation coils and incubated samples are aspirated back to the detector by flow reversal. This overcomes construction difficulties and allows the measurement of the sample blank value. (C) 1999 Elsevier Science B.V. All rights reserved.