Determination of peroxide value by Fourier transform near-infrared spectroscopy

A Fourier transform-near infrared (FT-NIR) method originally designed to de termine the peroxide value (PV) of triacylglycerols at levels of 10-100 PV was improved upon to allow for the analysis of PV between 0 and 10 PV, a ra nge of interest to the edible oil industry. The FT-NIR method uses convenie nt disposable glass vials for sample handling, and PV is determined by spec troscopically measuring the conversion of triphenylphosphine (TPP) to triph enylphosphine oxide (TPPO) when reacted with hydroperoxides. A partial-leas t-squares calibration was developed for 8 mm o.d. vials by preparing random ized mixtures of TPP and TPPO in a zero-PV oil. The method was validated wi th samples prepared by gravimetric dilution of oxidized oil with a zero-PV oil. It was shown that the American Oil Chemists' Society primary reference method was quite reproducible (+/-0.5 PV), but relatively insensitive to P V differences at lower (0-2) PV. The FT-NIR method on the other hand was sh own to be more accurate overall in tracking PV, but slightly less reproduci ble (0.9 PV) due to working close to the limit of detection. The sensitivit y and reproducibility of the FT-NIR method could be improved upon through t he use of larger-diameter vials combined with a detector having a wider dyn amic range. The proposed FT-NIR PV method is simple to calibrate and implem ent and can be automated to allow for routine quality control analysis of e dible fats and oils.