Validation of the Analytical Procedure for the Determination of Malondialdehyde and Three Other Aldehydes in Vegetable Oil Using Liquid Chromatography Coupled to Tandem Mass Spectrometry (LC-MS/MS) and Application to Linseed Oil

摘要

Secondary oxidation products of fatty acids, mainly aldehydes, are susceptible to cause significant deterioration in chemical, sensory and nutritional food properties, as well as adverse health effects. An analytical method involving separation by liquid chromatography coupled to the detection by tandem mass spectrometry (LC-MS/MS) has been developed to evaluate the concentration of four aldehydes in oil samples: malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), 4-hydroxy-2-hexenal (4-HHE) and 2,4-decadienal (2,4-DECA). The optimisation of the extraction, derivation, detection and quantification has been finalised for coconut oil, used as a model of vegetable oils. The method has been validated according to the criteria and procedure described in international standards. The evaluated parameters include specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, using the concept of accuracy profiles. These parameters have been evaluated during experiments planned on different non-consecutive days with coconut oil spiked at different levels of concentration. The validation of the developed analytical method showed that it is possible to analyse MDA, 4-HHE, 4-HNE and 2,4-decadienal in oil samples, in the same run, with a very good accuracy for MDA, and a defined accuracy at specified concentrations for the three other aldehydes. The accuracy profile of MDA showed a recovery rate of 100 % (+/- 1) and a maximum coefficient of variation for the intermediate precision of 14 % at 0.15 mg kg(-1). For the three other aldehydes, recovery rates ranged between 79 and 101 % and coefficient of variation for the intermediate precision between 13 and 23 %. In first pressure linseed oil, stored for several days at 60 A degrees C according to the Schaal oven test, it was shown that 4-HHE was the most produced aldehyde, reaching levels of 85 and 382 mu mol kg(-1) after 12 and 24 days, respectively, versus levels of 18 and 28 mu mol MDA kg(-1) of oil, respectively, and 17 and 51 mu mol 4-HNE kg(-1) of oil.