The fiber was conditioned daily prior to the extraction by
leaving it in the injection port for 10 min at 240 C. In all
experiments, 0.2 g of sodium chloride was added to 4mL of
aqueous sample in a 7mL vial containing a magnetic stir bar
(PTFE coated). Afterwards, the solution was spiked with a mixture
of selected VOC compounds and then the vial was sealed with a
PTFE-faced septum and an aluminum cap. The sample vials were
heated in a circulating water bath and agitated by a magnetic
stirrer. The extractionwas performed by exposing the fiber coating
to the headspace over the aqueous sample for 10 min at 30 C. After
performing the extraction, the fiber was withdrawn into the
external needle (22-G) and then it was immediately inserted into
the GC injector port for thermal desorption of analytes at 240 C
for 3 min.