Applications - Direct Thermal Extraction
C42
Scientific Instrument Services, Inc.
TM
Phone: 908-788-5550
www.sisweb.com/catalog/08/C42
To MS
or GC
Detector
GC Injection
Port
Capillary
Column
Cryo Trap
Sample
on Column
Temperature
Program for
GC Oven
Analysis
GC Oven
Sample
Heating
Blocks
Cross Section
of GLT
Desorption Tube
Inert
Glass
Lining
Needle
Silanized
Glass
Wool Plug
Solid Sample
1-500 mg or
adsorbent
resin
Silanized
Glass Wool
Plug
Carrier
Gas
Flow
Terpines
MW=136
Hydroxy-Terpines
MW=154
8e+07
7 .5e+07
7e+07
6 .5e+07
6e+07
5 .5e+07
5e+07
4 .5e+07
4e+07
3 .5e+07
3e+07
2 .5e+07
2e+07
1 .5e+07
1e+07
5000000
58.00
56.00
54.00
52.00
50.00
48.00
46.00
44.00
42.00
40.00
38.00
36.00
34.00
32.00
30.00
Time
Sesqui-Terpenes
MW=204
Technique: Direct Thermal Extraction of Solid Samples
Sample: 2.0 mg. crushed black pepper was placed inside the GLT desorption tube
Thermal Desorption: Block temperature: 150°C, Purge flow: 2.0 ml/min He,
Desorption time: 6.0 min. Initial column trap temperature: -40°C
Column: DB-5, 60 meter x 0.25 mm I.D., 0.25 u film, -40° to 280°C at 10°/min.
0
T i m e
1
4
3
5
6
7
8
2
10.00
12.00
14.00
16.00
18.00
20.00
22.00
24.00
26.00
28.00
2 0 0 0 0 0 0
3 0 0 0 0 0 0
4 0 0 0 0 0 0
5 0 0 0 0 0 0
6 0 0 0 0 0 0
7 0 0 0 0 0 0
8 0 0 0 0 0 0
9 0 0 0 0 0 0
1 e + 0 7
1 . 1 e + 0 7
1 . 2 e + 0 7
1 . 3 e + 0 7
1 . 4 e + 0 7
1 . 5 e + 0 7
1 . 6 e + 0 7
1 0 0 0 0 0 0
5. Gamma Terpinene
6. Methyl Salicylate
7. Eugenal
8. BHT - 160 ppm
1. Ethyl Butyrate
2. Isoamyl Acetate
3. Beta Pinene
4. Limonene
Technique: Direct Thermal Extraction of Solid Samples
Sample: 8.3 mg. of thinly sliced gum was placed inside the GLT desorption tube
Thermal Desorption: Block temperature: 100°C, Purge flow: 2.0 ml/min He,
Desorption time: 10.0 min. Initial column trap temperature: -40°C
Column: DB5-MS, 30 meter x 0.25 mm I.D., 0.25 u film, -40° to 280°C at 10° /min.
2
4
6
8
10
12
14
16
18
20
22
24
1
Limonene
8e+07
7 .5e+07
7e+07
6 .5e+07
6e+07
5 .5e+07
5e+07
4 .5e+07
4e+07
3 .5e+07
3e+07
2 .5e+07
2e+07
1 .5e+07
1e+07
5000000
Technique: Direct Thermal Extraction of Solid Samples
Sample: 2.0 mg. of candy was placed inside the GLT desorption tube
Thermal Desorption: Block temperature: 150°C, Purge flow: 2.0 ml/min He,
Desorption time: 6.0 min. Initial column trap temperature: -40°C
Column: DB-5, 25 meter x 0.25 mm I.D., 0.25 u film, -40° to 280°C at 10°/ min.
T
he technique of Direct Thermal Extraction permits the
analysis of solid samples without any prior solvent
extraction or other sample preparation. Solid samples
between 1 and 500 milligrams are placed directly inside the GLT
desorption tube between two glass wool plugs. The desorption
tube needle is attached to one end of the sample tube. The
desorption tube with sample enclosed is then attached to the
Short Path Thermal Desorption System, purged with carrier gas
to remove all traces of oxygen and injected into the GC injection
port. The preheated heater blocks are closed around the
desorption tube thereby permitting the thermal extraction of the
volatiles and semi-volatiles present into the GC injection port.
After the desorption is complete, these components, which have
been trapped on the front of the GC column, are eluted and
separated via a temperature program of the GC oven. This
technique is useful for the analysis and quantification of a wide
variety of low moisture content solid samples including
vegetation, food products, pharmaceuticals, building materials,
forensic samples and packaging products. By the proper
selection of the desorption block temperature, the number and
molecular weight distributions of components in the samples can
be selected.The following three pages show applications of the
Direct Thermal Extraction technique for the analysis of the
volatiles and semi-volatiles in a wide range of sample matrices.
Food Products
The natural and artificial flavors, preservatives, oils, and other
volatile and semi-volatile components in low moisture content
food samples can be readily extracted and identified via the Direct
Thermal Extraction Technique.
Black Pepper
Fruit Flavored
Chewing Gum
Sugar Candy
Terpenes
MW=136
Hydroxy-Terpenes
MW=154
Sesqui-Terpenes
MW=204
See WEB Site for complete
Application Notes
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