Rapid Separation of Free Sterols in Edible Oils by On-Line Coupled Reversed Phase Liquid Chromatography−Gas Chromatography

Abstract

A rapid analysis of the sterol fraction of oils by on-line reversed phase liquid chromatography-gas chromatography (LC-GC) is described. Methanol:water is used as eluent in the LC preseparation step, 2000 µL/min being the speed of sample transfer. A programmed temperature vaporizer is used as an interface for the LC-GC equipment, and the solvent elimination is performed simultaneously in both the evaporative and nonevaporative modes so that a 3000-µL LC fraction can be transferred into the GC. The proposed procedure only demands previous dilution of the oil sample with CH 2 Cl 2 and allows the analysis of the sterol fraction in only 20 min, including the oil sample preparation and the LC-GC analysis itself.

Application of Chromatographic and Infra-Red Spectroscopic Techniques for Detection of Adulteration in Food Lipids: A Review

“…The method of capillary GC followed by methanolysis could help reduce the total analysis time as it eliminates the need for saponification, extraction, and derivatization steps [54]. On-line coupling of LC-GC might offer rapid separation of free sterols in edible oils and fats since sample preparation can be integrated into the chromatographic procedure [57]. A detailed account of the developments in the analysis of sterols using on-line coupled LC-GC systems could be found elsewhere in the literature [58].…”

Trends in Edible Vegetable Oils Analysis. Part A. Determination of Different Components of Edible Oils – A Review

“…On-line coupling of high pressure liquid chromatography and liquid chromatographygas chromatography can also be used, which enables the removal of most of the undesirable sample components during the LC step, because of which, it can be better separated in the GC [Senorans et al, 1996;Villen et al, 1998]. Different transfer techniques have also been applied, as well as coupling techniques for both chromatograph interfaces, yet most LC-GC applications require a normal phase set-up (NP-LC).…”

“…Analysis in a reversed phase set-up, which widens the field of application of this technique and provides the possibility of simultaneous analysis of compounds from different groups, is possible after applying an evaporizer located between the two chromatographs with a programmed temperature. Before analysis, the oil samples are dissolved in dichloromethane [Senorans et al, 1996]. This technique has been also applied for determining squalene.…”

“…A LC-GC coupling enabled a simultaneous increase in selectivity and method output, which is required in the analysis of complex samples [Senorans et al, 1996;Villen et al, 1998]. …”

Analysis of free and esterified sterols in edible oils by online reversed phase liquid chromatography–gas chromatography (RPLC–GC) using the through oven transfer adsorption desorption (TOTAD) interface

“…Biedermann et al (1993) proposed a method to substitute the saponification procedure by transesterification followed by online LC-GC. An LC-GC method using reversed phase was developed by Señoráns et al (Señoráns, Tabera, & Herraiz, 1996;Señoráns, Villén, Tabera, & Herraiz, 1998) using a programmed temperature vaporiser (PTV) as interface. Elimination of the extremely large volume of vapour resulting from the aqueous eluent during LC-GC transfer was promoted through the injector body by removing the GC column end from the injector body.…”