aromatic fraction
through two-step silica gel column chromatography
Filtered water was extracted by the solid-phase extraction (SPE)
method, which is based on hydrophobic retention of the sorbent for
the interfering components. The SPE cartridge type SiliaPrep C18 nec
(23%) was used for the PAH study (Mirsadeghi et al., 2011). For the preparation
of the sample, 5–25 ml of methanol and five surrogate PAHs
were added to 200 ml of filtered water samples. The column of cartridge
was conditioned with methanol followed by sample pre-treatment
solvent (water: methanol 85:15 v/v) with a 2–4 ml/min flow rate. The
water sample was loaded directly on top of the cartridge with the
same flow rate as the cartridge volume. A small layer of sodium sulfate
anhydrous was then added to the top of the cartridge. Next, the sample
was washed with sample pre-treatment solvent with 1–2 ml min−1
flow rate. At the PAH elution step, 1 ml multiple two of dichloromethane
with 1 ml min−1 flow rate were introduced to the column of cartridge