Analysis of trace aldehydes in olive oil utilizing quantitative 1D and 2D nuclear magnetic resonance spectroscopy

Olive oil is known to contain a number of trace components possessing health promoting potential. Among these are hydroxytyrosol and tyrosol derivatives including the dialdehydes oleacein and oleocanthal and the monoaldeydes oleuropein aglycon and ligstroside aglycone. Chromatographic analysis of these compounds is problematic because of reactivity with mobile and stationary phase components.¹ Nuclear Magnetic Resonance (NMR) spectroscopy has proven to be well suited for analyses of complex chemical mixtures. Quantitation of key trace analytes in the presence of very strong signals from the bulk matrix can be problematic using typical broad band excitation due to dynamic range limitations. These limitations can be overcome by the use of band selective shaped pulses to excite only the region containing the minor analytes while excluding the regions containing strong signals such as the prevalent lipid resonances in the olive oil matrix. Region selective 1D and 2D NMR methods for direct quantitation of µg/g aldehyde concentrations in olive oil without the need for extraction or concentration of analytes will be discussed. Implementation into high throughput automated analysis methods will also be presented.

¹Karkoula E.; Skantzari A.; Melliou E.; Magiatis, P., Quantitative Measurement of Major Secoiridoid Derivatives in Olive Oil Using qNMR. J. Agric. Food. Chem. 2014; 62, 600 – 607