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.

An Overview of Chemical Profiles, Antioxidant and Antimicrobial Activities of Commercial Vegetable Edible Oils Marketed in Japan

“…Edible vegetable oils are important sources of fatty acids (mainly unsaturated), which are predominantly triglycerides (95–98%), whist the remaining (5–2%) consists of complex mixtures of minor compounds such as sterols, triterpenic dialcohols, diglycerides, and squalene [ 1 , 2 , 3 , 4 , 5 ]. Antioxidants and antibacterial activities are key agents for improving oxidative stability.…”

Determination of Vitamin E in Cereal Products and Biscuits by GC-FID

“…There is no clear definition for superfoods; it is a term used for foods that combine the nutritional health benefits and disease prevention of different foods [ 4 ]. These foods are mainly composed of cereals, fruits, beans and vegetable oils [ 5 , 6 , 7 , 8 , 9 , 10 ]. Vitamin E occurs in all these foodstuffs, but its content depends on the superfood composition.…”

Properties of a New Food Supplement Containing Actinia equina Extract

“…According to the well assessed procedure [ 13 , 14 ], the final solution was made up of H 2 O/D 2 O with 1:9 volumetric ratio and with 1 mM of TSP (3-(Trimethylsilyl) propionic-2,2,3,3-d 4 acid sodium salt, used as NMR frequency and quantification standard with δ = 0.0 ppm), 600 mM of phosphate buffer solution (to keep costant pH = 7.24), and 0.2% of NaN 3 (able to inhibit interfering bacterial growth). The resulting solution was poured into a 5 mm NMR text-tube.…”

“…The NMR analysis was carried out at 25 °C with a NMR Bruker Avance III 500 MHz spectrometer (Bruker, Milan, Italy) equipped with a SMARTprobe with gradients. After optimization of the field homogeneity and calculation of the 90° pulse (8 μs @ 3dB) the 1 H-NMR noesypresat experiments were run to guarantee water suppression and detection and quantification of free α-amino acids according to the Multiple Assignment Recovered Analysis (MARA-NMR) quantification technique [ 13 , 14 ].…”