The residual pyrene in samples was extracted by ethyl acetate
(Mahanty et al., 2008) and analyzed by high-performance liquid
chromatography (HPLC) with UV detector at 254 nm and C18 reverse-
phase column (dimensions 0.25 mm150 mm), methanolwater
(90/10, v/v) was used with a flow rate of 1 mL/min as a
mobile phase. The injection volume was 20 μL (Chen et al., 2014).
Detection limit of pyrene was 0.5 μg/L.