2.3. HS-SPME procedure
HS-SPME extraction was performed using a Supelco (Bellefonte,
USA) manual holder containing a fiber assembly with a 100 μm polydimethylsiloxane
(PDMS) coating. The fiber was conditioned in the injection
port of a gas chromatograph at 250 °C for 30 min prior to use and
blank desorption was performed. 2 mL of aqueous sample (standard
or real) was placed in 4 mL glass vial with PTFE/silicone septa, which
contained 10% (w/v) sodium chloride salt. The fiber was exposed to
the headspace of a sample, kept at a selected temperature for a set
time, retracted into a needle, and introduced into the injection port of
gas chromatograph. Extraction was supported by magnetic stirring at
the highest possible level. A fiber blank experiment was performed to
ensure that there were no contaminants on the fiber.
For optimization of HS-SPME process, the factors affecting extraction
efficiency (headspace volume, extraction time, temperature,
sample ionic strength and agitation speed) were investigated.