Comparison of differently coated SPME fibres applied for monitoring volatile substances in vegetable oils

Abstract

Solid-phase microextraction (SPME) was developed to determine volatile substances from liquid, gas or even solid materials. This technique has been successfully applied for soil, waste water, blood and urine samples, but in spite of its advantages there are still few applications for vegetable oils. SPME is applicable to determine the aroma and other volatile compounds of the oil, which are characteristic to its origin and oxidative status.In this study the sensitivity and selectivity of some commercially available SPME adsorption materials (polydimethylsiloxane, divinylbenzene, carboxen) were compared. The diverse types of stationary phases were investigated by applying standard oils containing volatile substances from 9-90 mg/kg concentrations. SPME fibre was placed into the headspace of an oil sample in a 30-ml headspace vial thermostated at 80 °C for 45 min. The extracted volatile materials were desorbed from the fiber in the injection port of the gas chromatograph at 250 °C. Identification of the extracted compounds is based on pure standards and mass spectra. The reliability of the SPME sampling method was studied by parallel measurements.The 2-cm long fibre coated with divinylbenzene (50 µm) and carboxen (30 µm) proved to be the most appropriate to determine the volatile oxo-materials from vegetable oils. The method was successfully applied to follow up the formation of volatile substances (e.g. hexanal, t-2-hexenal, t-2-heptenal, t-2-octenal, nonanal, t,t-2,4-nonadienal, t-2-nonenal, t-2-decenal, t,c-and t,t-2,4-decadienal, 2-pentylfuran, 1-octen-3-ol) during deep frying in sunflower oil.

Analysis of volatile compounds and triacylglycerol composition of fatty seed oil gained from flax and false flax

“…Oil samples (10 g) were filled into SPME vials, sealed with caps and extracted isothermally for 10 h to achieve sufficient amounts of analytes at room temperature, by using a pre-conditioned Supelco 57348 2 cm, 50/30 mm DVB/ Carboxen/PDMS Stable-Flex fibre, which is especially suited for analysing volatile compounds, as shown by Doleschall et al [26]. After sampling, the SPME device was placed into a GC-MS instrument.…”

Identification of some rancidity measures at the end of the shelf life of sunflower oil

“…Peaks were identified by comparison of their retention times to those of a standard mixture. Hex content was determined by placing an oil sample (2 g), containing dodecane as internal standard, in a 20-mL headspace glass vial, into which a 75-mm carboxen on a polydimethylsiloxane SPME fiber had been inserted into the seal, and heating at 80 7C for 30 min [24,25]. The adsorbed volatiles were analyzed by GC using a Supelco SPB-1 capillary column (30 m60.25 mm I.D.…”

Accurate determination of hexanal in beef bouillons by headspace solid‐phase microextraction gas‐chromatography mass‐spectrometry

“…Helium was the carrier gas at a linear velocity of 1.00 mL/min. Both polar [14] and non-polar columns [26] were evaluated to analyze volatile products. Better chromatographic separations were achieved with the non-polar (DB-5MS 3060.25 mm, 0.25 mm; J&W, Palo Alto, CA, USA) capillary column [15,16].…”