extraction parameters, an analyst can ensure highly
consistent, quantifiable results from low concentrations of analytes. A variety of fibers is shown in T- 2.
The effect of choosing the fiber is demonstrated
in F- 2.
The identification of the peaks in the above chromatograms is shown in T- 3.
When deciding which sample extraction approach
to use for flavor analysis, it is important to understand that each will result in a different profile. The
technique should be chosen to enable the required
sensitivity and selectivity to be achieved. The nature
of the product or ingredient matrix should always
be considered and the link back to sensory data is
required to enable a full understanding of the impact
of analytical results. 4
Purge and trap has been used for decades to
extract volatile molecules from a solid or liquid
matrix for introduction into GCMS for separation
and identification. The volatiles are concentrated
onto an absorbent trap, followed by thermal
F- 1. Thermal desorption of the twister in the
TDU followed by cryofocusing of the analytes in
the CIS and temperature programmed transfer
to the GC column2
F- 2. Multivitamin juice chromatogram obtained from
EG-Silicone and PDMS SBSE Twistera, non-polar column
separation. Features 10 mL sample, 1000 rpm for one hour
at room temperature3
desorption into a GCMS. Sample matrices can range
from soil, plastics, foods, flavor, fragrance, emulsions
Thermal desorption technique utilizes heat to
increase the volatility of the adsorbed substances
such that they can be removed from the solid matrix.
When the thermal desorption system is combined
with GCMS, the results meet current requirements
with sensitivity and dynamic range.
The second stage of flavor analysis is choosing the right GC column for separation; there are
there main types to be considered firstly: Apolar
column, e.g. DB- 5 MS, DB- 1 MSb; polar column,
e.g. Stabilwaxb-MS and column for volatiles, e.g.
Another method to be considered is two dimensional GCMS chromatography, which employs a
T- 2. Variety of ibers offered by Sigma-Aldrich
SPME Metal Alloy Fiber Assemblies Polydimethylsiloxane (PDMS) fibers, non-polar
Carboxen/Polydimethylsiloxane (CAR/PDMS) fibers Carbowax-Polyethylene Glycol (PEG) fibers, polar
Polydimethylsiloxane/Divinylbenzene (PDMS/DVB) fibers Polyacrylate (PA) fibers, polar
Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) fibers Carbowax/Templated Resin (CW/TPR) fibers, polar
a PDMS SBSE Twister is a registered tradename of Gerstel.
b DB- 5 MS and DB- 1 MS are Agilent J&W products.
c Stabilwax-MS is a registered tradename of Restek
d ZB-624 is a Phenomenex product.