Automated and simultaneous determination of free fatty acids and peroxide values in edible oils by FTIR spectroscopy using spectral reconstitution.

This paper described an FTIR spectrometer coupled to an auto-sampler and some attendant methodologies for a direct free fatty acid (FFA) method and triphenylphosphine (TPP)-based method for determination of FFA and peroxide value (PV) of edible oils by FTIR spectroscopy using spectral reconstitution. The viscosity of oil samples is reduced by mixing them with a diluent; such lowered viscosity allows them to be readily loaded into a flow-through transmission cell. The spectra of the neat oil samples are then reconstituted from those of the diluted samples by using the absorption of a spectral marker present in the diluent to determine the dilution ratio. For the direct FFA analysis, quantification is achieved using the (COO(-)) band at 1712 cm(-1), while PV is determined using triphenylphosphine oxide (TPPO) absorption bands at 542 cm(-1). Calibration procedures and data are presented. Validation and performance data obtained with this automated system demonstrate that it is capable of analyzing approximately 90 samples/h, a rate commensurate with the throughput required by commercial contract or high-volume process control laboratories.