2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
Table I
RSD in determination of analytes
Analyte RSD Analyte RSD
α-pinene 13 menthone 32
camphene 11 borneol 18
sabinene 14 estragol 28
β-pinene 9 α-cubebene 12
β-myrcene 7 thymol acetáte 38
α-phellandrene 10 ylangene 31
3-carene 7 copaene 27
α-terpinene 7 α-bourbonene 34
2-nitro-p-cymene 3 isocaryophyllene 35
limonene 23 β-caryophyllen 26
eucalyptol 8 humulene 31
γ-terpinene 4 α-caryophyllen 36
β-terpineol, cis- 15 isoledene 32
linalool 13 α-muurolene 36
thujone 22 epizonarene 36
camphor 12 karyophyllene oxide 34
were as follows: the duration of sorption was 15 minutes at
a temperature of 30 °C. This temperature was also used for
sample conditioning. Fig. 2. shows the comparison between
the different durations of sample conditioning (0; 5; 10; 15;
20 minutes) and it is seen that the 5-minute conditioning is
the most suitable as it gives the highest response for the majority
of target analytes.
The repeatability of the method was determined based
on 5 repetitions and is expressed as a relative standard devi-
s462
ation (Table I). Terpenes are listed in the table according to
their increasing molecular weight. It follows from the results
that lower-molecular-weight terpenes have better repeatability
than more volatile terpenes with higher molecular weight.
Standard deviations vary in a rather wide range of 28–38 %
for substances with higher molecular weight which may be
attributed to the optimization of the SPME method where
some parameters (particularly the duration and temperature
of sorption) were chosen at such levels to match for the whole
group of 32 monitored substances.
Conclusions
SPME conditions used for optimalization of head-space
method were follows: 15 min exposition of PDMS-DVB
(65 µm) fiber at 30 °C in head-space above 0.5 g of spice
sample in vial. The incubation of sample was 5 minutes at
extraction temperature 30 °C.
This work has been supported by by the grants given by
Ministry of Education, Youth and Sports of the Czech Republic
no. 6215712402.
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