Comparison of different injection modes in edible oil minor components analysis

Abstract

Waxes and fatty acid alkyl esters are minor components used as official parameters to control the authenticity and quality of a high-value olive oil product. A poor measurement can lead to a misleading classification of the oil. The official method requires their analysis together by capillary gas chromatography equipped with a flame ionization detector and an on-column injector to avoid discrimination and thermal degradation. The degradation can occur to a different extent if different (and not properly optimized) injectors are used. However, other injection techniques, such as programmed-temperature vaporizer, are much more versatile and more widespread. The aim of the present work was to compare the performance of a programmed-temperature vaporizer injector, in on-column and splitless mode, with the on-column injector to analyze alkyl esters and waxes. Discrimination among high-boiling compounds was evaluated, as well as the occurrence of thermal degradation, especially of sterols and diterpene alcohol (phytyl and geranylgeraniol) esters. A proper optimization of a programmed-temperature vaporizer injection, with particular attention to the liner selection, was proven to provide comparable results to the traditional on-column injection. A performance comparison was carried out both on standard mixtures and on real oil samples.

Identification of foods that affect the anti‑cancer activity of pitavastatin in cells

“…The potent effect of the sunflower oil extract in suppressing the cytotoxic effect of pitavastatin we observed is particularly significant because apart from its use to fry food, sunflower oil is also an ingredient found in approximately 1,000 manufactured food products (16). Oil extracted from hazelnuts, pecans and almonds also have been reported to contain geranylgeraniol (17,18). In contrast to these oils, rapeseed oil lacks at least the common 22 and 24 carbon fatty acid esters of geranylgeraniol (7) and extracts from rapeseed oil also failed to inhibit the activity of pitavastatin in our experiments.…”

Importance of some minor compounds in olive oil authenticity and quality

“…Fatty acid alkyl esters (FAAEs) are produced by enzymatic reaction of free fatty acids with low molecular weight alcohols, mainly methanol and ethanol, under acidic conditions yielding methyl (FAME) and ethyl esters (FAEE), respectively (Bajoub et al, 2018;Pérez-Camino, Moreda, Mateos, & Cert, 2002;Pérez-Camino, Cert, Romero-Segura, Cert-Trujillo, & Moreda, 2008). Critical levels of FAAEs (sum of FAME and FAEE) for olive oil have been defined first by a Commission Regulation (EU) No 61/2011 (EU, 2011) as a quality parameter since the formation of these compounds indicates fermentation (mainly ethanol formation) as well as degradation processes (mainly methanol formation) occurred during storage (Purcaro, Barp, & Conte, 2015). In addition, it is not possible to remove FAAEs without leaving by-products such as stigmastadiene in high temperature treatments (Purcaro et al, 2015).…”

Fatty Acid Ethyl Esters in Virgin Olive Oils: In-House Validation of a Revised Method

“…This represents the only difference in the gas chromatographic step between the proposed method and the official one for which an OCI is needed. The use of an OCI is required for many applications in the analysis of fats and oils to avoid discrimination effects and reduce degradation of labile compounds (Purcaro et al, 2015) [ 21 ], but it is not widely applied in quality control laboratories, and, thus, an alternative is needed. The PTV injector represents a more versatile option as the temperature control is time-programmed and the injection mode (split/splitless) can be optimized according to the specific application (Engewald et al, 1999) [ 32 ].…”

“…2019/1604 [ 17 ] introduced the possibility to replace n-hexane with iso-octane. A further revision found in the literature involves the injection technique used for GC analysis: A programmed temperature vaporizer (PTV) injector used as an alternative to the on-column one required by the regulation gives comparable results in analysis of real-world samples (Purcaro et al, 2015) [ 21 ]. Moreover, other analytical techniques have been tested as alternatives to the official method.…”