Quick unreferenced NMR quantification of Squalene in vegetable oils

Abstract

We present here a simple method for the rapid quantification of squalene in vegetable oils by NMR (Nuclear Magnetic Resonance). The method was validated by adding internal standards to several vegetable oil samples. Quantification was accomplished by exploiting the characteristic resolved signal of terminal methyl groups at 1.67 ppm, which allowed squalene quantification regardless of the hydrophobic matrix. Theoretical principles are fulfilled by the method and, despite the general belief that NMR displays intrinsic low sensitivity, acceptable accuracy (<4%) and reproducibility (<6%) can be reached when squalene is over 2000 ppm, even in “worst case scenarios.” This method may be useful in the continuing efforts to rapidly generate accurate and complete quantitative data suitable for inclusion in the identification labels of vegetable oil products.Practical applications: Unreferenced and accurate quantification of squalene in vegetable oils, was validated here by the analysis of several 1H‐NMR spectra of vegetable oils and of standard doped samples. Moreover, we found that squalene can affect the NMR spectra of other quantifiable species. These data may be useful to produce more accurate and precise analyses of vegetable oil using their 1H‐NMR profiles.Collectively, our data indicate that quantification of squalene in vegetable oils can be easily accomplished by 1H‐NMR, opening new potentialities in NMR‐based fat analysis. The ability of squalene to alter NMR spectra should be taken into account, particularly in oils with a high squalene content, such as Sicilian olive oils.