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Figure 2 Verify initial results by analyzing re-collected samples.
Analysis of headspace collected above boiling, genetically-modified potatoes.
Repeat analysis of the re-collected sample demonstrated excellent recovery of
reactive monoterpenes, such as α -copaene.
Figure 3 Thermal desorption allows selective elimination of water
and >99% of ethanol vapor, enhancing the determination of key
olfactory components.
Analysis of whisky headspace by GC/FID.
into the GC carrier gas stream, no manual sample
preparation is required and the problems associated
with solvents—masking of peaks of interest, loss
of volatiles, and variable extraction efficiency—are
eliminated.
Lower Detection Limits and
Repeat Analysis
The latest TD systems use thin-walled quartz traps
capable of heating at rates over 100°C/sec., maxi-
mizing desorption efficiency and lowering detec-
tion limits. They also incorporate split re-collec-
tion for repeat analysis and simple validation of
recovery (Figure 2) through the analytical system.
Newer thermal desorption systems are also capa-
ble of transferring the vapor profile constituents
into the GC capillary column in volumes of carri-
er gas as low as 100µL. This means that significant
concentration enhancement factors can be
achieved—typically from 103 to 106—depending
on the number of concentration/desorption steps.
TD also allows volatile interferences such as water
and ethanol to be purged to vent prior to analysis,
making it easier to discriminate between samples
according to the key olfactory components
(Figure 3).
Summary
Thermal desorption offers an automatic, high-
sensitivity alternative to conventional liquid
extraction methods for aroma profiling by
GC/MS. It allows vapor profile constituents to be
cleanly separated from the sample matrix and
facilitates selective purging of volatile interfer-
ences in many cases. This helps to ensure that the
vapor profile analyzed is most representative of
the aroma perceived by consumers and that key
olfactory compounds can be identified and meas-
ured at the lowest levels possible.
free literature
Thermal Desorption: A Practical
Applications Guide
Download your free copy from
Technical Guide
lit. cat.# FFTG1037
α-copaene
Whisky
repeat analysis
initial analysis
Thermal Desorption Tube Sorbent Applications
Tenax TA Vapor phase organics
from C6/7 to C26
Graphitized Carbon Vapor phase organics
from C5/6 to C14
Tenax GR/Carbopack B Vapor phase organics
from n-C5/6 to n-C20 (EPA
Methods TO-14/TO-15/TO-17)
Carbopack B/Carbosieve SIII Vapor phase organics from
n-C2/3 to n-C12/14 (EPA
Methods TO-14/TO-15/TO-17)
Tenax TA/Graphitized Vapor phase organics from
Carbon/Carboxen 1000 C2/3 to C20
Carbopack C/Carbopack Vapor phase organics from
B/Carbosieve SIII n-C2/3 to n-C16/20 (EPA
Methods TO-14/TO-15/TO-17)
Thermal Desorption Unit Tubes, Unconditioned
Fits Markes ULTRA-UNITY, PerkinElmer, and Shimadzu thermal desorbers.
Unconditioned
Stainless Steel Glass
Description qty. cat.# price cat.# price
TDU Tubes, Tenax TA 10-pk. 24056 24062
TDU Tubes, Graphitized Carbon 10-pk. 24057 24063
TDU Tubes, Tenax GR/Carbopack B 10-pk. 24058 24064
TDU Tubes, Carbopack B/Carbosieve SIII 10-pk. 24059 24065
TDU Tubes, Tenax TA/Graphitized
Carbon/Carboxen 1000 10-pk. 24060 24066
TDU Tubes, Carbopack C/Carbopack
B/Carbosieve SIII 10-pk. 24061 24067