3
Sample Measurements
The active compounds capsaicin and dihydrocapsacin
elute with only a short retention time difference. A good
separation free from peak tailing is necessary for a reliable
peak integration for low RSD values at low concentration
levels (Figure 3). It was found with different types of GC
columns that the quality of the column deactivation, age
of the column and matrix deposits have a detrimental
effect on the capsaicin and dihydrocapsacin peak shape
and quantitative reproducibility. Also, piperine was
affected while thymol always showed symmetrical peak
shapes, apparently being unaffected by the increasingly
active column film conditions.
To preserve inert conditions with the inlet liner and
analytical column for high quantitative precision and
reproducible results with a high number of samples, an
analyte protectant was co-injected with the extract of
active analytes
[4, 5, 6]
. These compounds are known to be
used in pesticides analysis, also comprising a number of
active and polar compounds. A concentration of 2 ppm
of sorbitol was added to the extracts in all experiments.
Figure 2. TRACE 1310 GC method setup SSL injector
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
Time (min)
0
20
40
60
80
100
0
20
40
60
80
100
Relative Abundance
RT: 12.64
AA: 54365
SN: 59 RT: 12.89
AA: 44242
SN: 39
RT: 14.70
AA: 80196
SN: 23
RT: 14.44
AA: 81163
SN: 22
(A)
A 15 m column, well deacƟvated
(B) A 30 m column, with acƟve sites
Figure 3. Capsaicin and dihydrocapsacin elution, (A) from a short 15 m well deactivated
capillary column at 100 ppb, (B) from a 30 m column with active sites at 500 ppb,
resulting in poor peak shape and low S/N value. Both column dimensions are 0.25 µm
film thickness, 0.25 mm ID, and no analyte protectant was added.
