Biomedical subjects

M Adahchour

Publications and source records attributed to M Adahchour.

3 recordsLinked to original sources

PubMed2003

Single-jet, single-stage cryogenic modulator for comprehensive two-dimensional gas chromatography (GC x GC).

A simple, single-stage CO2 jet modulator has been designed, which cools only a single, ca. 10 mm long section of the front part of the second-dimension column of a comprehensive two-dimensional gas chromatographic (GC x GC) system. Direct heating by means of the GC oven air effects remobilization of the small fractions trapped upon eluting from the first-dimension column within a predetermined short period of time. Evaluation of the present modulator for the GC x GC separation of (very) polar flavour as well as non-polar compounds shows that the analytical performance of the single-stage modulator is closely similar to that of earlier reported, more complex, types of modulator.

Food Analysis↗

PubMed2001

Simple, non-moving modulation interface for comprehensive two-dimensional gas chromatography.

A simple, non-moving dual-stage CO2 jet modulator is described, which cools two short sections of the front end of the second-dimension column of a comprehensive two-dimensional gas chromatograph. A stream of expanding CO2 is sprayed directly onto this capillary column to trap small fractions eluting from the first-dimension column. Remobilization of the trapped analytes is performed by direct heating by the GC oven air. Installation, maintenance and control of the modulator is simple. Focusing and remobilization of the fractions is a very efficient process, as the bandwidths of the re-injected pulses are less than 10 ms. As a result, alkane peaks eluting from the second-dimension column have peakwidths at the baseline of only 120 ms.

Carbon Dioxide↗

PubMed1999

Trace-level determination of polar flavour compounds in butter by solid-phase extraction and gas chromatography-mass spectrometry.

Volatile compounds are responsible for the aromas of butter. A simple technique for the determination of these components is described which is based on solid-phase extraction (SPE) after melting of the butter and separation of the aqueous phase from the fat. Volatile flavours present in the water fraction are collected by off-line SPE on cartidges packed with a copolymer sorbent. After desorption with 500 microliters of methyl acetate, 1-microliter aliquots are quantified and/or identified by gas chromatography-mass spectrometry. The procedure was tested with respect to recovery, linearity and limit of detection in real-life samples using five polar model analytes. It allows the characterisation of polar flavour compounds in butter prior to and after heat treatment at 170 degrees C. From the five model compounds, vanillin, traces of diacetyl and maltol were found to be present in the butter samples. After heat treatment 500-1000-fold increased concentration of maltol, and substantial amounts of furaneol were detected.

Benzaldehydes↗