Cumulative solid phase microextraction sampling for gas chromatography-olfactometry of Shiraz wine

Area of Science:

• Analytical Chemistry
• Food Science
• Sensory Science

Background:

• Solid phase microextraction (SPME) coupled with gas chromatography-olfactometry (GC-O) is standard for aroma-active compound determination.
• Current limitations include restricted method sensitivity and selectivity due to small fiber volumes and limited coating phases.

Purpose of the Study:

• To enhance the sensitivity and selectivity of SPME-GC-O for aroma-active compounds in wine headspace.
• To investigate a cryogenic trapping (CT) approach by coupling multiple SPME sampling events.

Main Methods:

• Multiple SPME sampling events using different polymer coatings (polyacrylate and triple-phase polydimethylsiloxane/divinylbenzene/carboxen) were performed.
• Desorbed solutes were accumulated by CT at the front of a Wax capillary column before GC-O analysis.
• The combined sampling approach (PADC) was tested for Shiraz wine volatiles.

Main Results:

• Cryogenic trapping effectively retained volatile compounds, including alkanes (decane and greater) and polar alcohols (methanol).
• Chromatographic signals increased with cumulative SPME samplings, showing good correlation.
• The PADC approach yielded aromagrams comparable to the sum of individual fiber coatings, with enhanced olfactory response after multiple sampling events.

Conclusions:

• The developed CT-coupled multiple SPME method offers a simple and effective way to enhance sensitivity and reduce discrimination in wine volatile analysis.
• Further development of separation strategies is needed for improved individual compound resolution in single-dimensional GC.