Determination of beer aroma compounds using headspace solid-phase microcolumn extraction.

A rapid sampling technique for the analysis of beer aroma compounds is described. The headspace (10 ml) is passed through the microcolumn filled with 5mg of Tenax TA and thermally desorbed in a modified GC inlet (modification is described). Eight compounds (from acetaldehyde to 2-phenylethanol) in four beer samples were analyzed. The correlation coefficients (r(2)), repeatability (RSD) and limits of detection (LOD) were 0.9973-0.9994, 2.1-6.9% and 0.00002-0.13 mg/l, respectively. The methodology can be useful for routine beer sample analysis.

Solid-phase microcolumn extraction and gas chromatography-mass spectrometry identification of volatile organic compounds emitted by paper.

A rapid non-destructive sampling technique for the analysis of volatile organic compounds (VOCs) emitted by paper sheets is described. A capillary, which is connected to a microcolumn packed with Tenax TA, is inserted between two sheets at the centre of a paper stack encapsulated inside a PET/Al/PE composite foil. The other end of the microcolumn is connected to a gas-tight syringe and an appropriate volume of gaseous phase is aspirated. The microcolumn is then thermally desorbed in a modified GC inlet (modification is presented) and analysed by gas chromatography-mass spectrometry (GC-MS). In the chromatogram from the analysis of artificially aged paper sample 21 compounds were identified. Advantages of the method including the short sampling time (1 min), simplicity and economic aspect are discussed.

On-column injection system for use of large diameter inside needle capillary adsorption trap devices.

Direct coupling of the needle trap to the capillary column in the split/splitless gas chromatographic (GC) inlet with simple modification facilitates full exploitation of the column efficiency, even when using the large volume trap filled with 35 mg of Tenax TA. A schematic diagram of the inlet and of the new modification of the INCAT device and an example of BTEX (benzene, toluene, ethylbenzene and xylenes) analysis is presented. Determination of the repeatability of BTEX analyses resulted in relative standard deviations of 2.4-3.6%.

Analysis of volatiles in water using headspace solid-phase microcolumn extraction.

A rapid solvent-free sample preparation method is presented in which volatilized organic substances are extracted via a solid-phase microcolumn mounted on a gas-tight syringe by the aspiration of an appropriate volume of headspace (tens of millilitres) of the sample under investigation. The microcolumn with the analytes concentrated on an adsorbent material is then transferred to the analytical instrument for desorption and analysis. The instrumental set-up consists of a Twister desorption unit (Gerstel) mounted on an Agilent 6890 GC system equipped with a CIS 4 programmed temperature vaporiser injector and coupled with an Agilent 5973 MS system. The instrumentation is slightly modified in comparison with the analysis made with a twister (stir bar coated with a layer of polydimethylsiloxane) after stir bar sorptive extraction and, thus, its utilization has been extended. For volatiles in water, the method is applicable to the qualitative screening at the microg/l to sub-microg/l level and to the quantitative determination at the ng/l level.