Headspace isolation, combination with

The GC-O techniques described above mainly deal with aroma extracts (liquids) isolated from the food. Recently, Guth and Grosch reported a new concept in aroma research using static headspace in combination with GC-O (18). The... 

The use of headspace solid-phase microextraction (HS-SPME) combined with GC was effective for isolation and determination of alkylpyrazines in cocoa liquor <2004JBS267, 2004MI291>, and similarly methoxypyrazine in wine was analyzed by HS-SPME/2-D GC <2005MI1075>. 

Methoxypyrazines are compounds with very low detection thresholds which must be determined at very low levels. For these compounds, different selective isolation methods have been proposed (Allen et al. 1994 Sala et al. 2002). Some authors use a simple extraction (Kotseridis et al. 1999 Falcao et al. 2007) or an optimized headspace SPME procedure (Chapman et al. 2004 Prouteau et al. 2004) using in most cases isotopically-labelled internal standards to compensate for matrix effects. In spite of the claims of the authors, all these methods present some difficulties to accurately determine the compounds at the lowest levels at which they can be found. A recent report has presented an advanced method combining the preconcentration ability of headspace SPME with the selectivity of comprehensive GC (Ryan et al. 2005). 

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