Application of pressurized liquid extraction followed by gas chromatography-mass spectrometry to determine 4-nonylphenols in sediments

A time- and solvent-saving method, pressurized liquid extraction (PLE), to extract 4-nonylphenol (4-NP) in sediment was developed. The effects of various operational parameters (i.e., temperature, pressure, etc.) for the quantitative extraction of 4-NP by PLE were investigated. The analytes were then identified and quantitated by a large-volume injection GC-MS technique. The 4-NP can be completely extracted by methanol at 100 degrees C and 100 atm combined with 15 min static and then 10 min dynamic extraction steps (1 atm = 101,325 Pa). Recovery of 4-NP in spiked blank kaolin samples was 98% with 5% RSD. The degrees of recovery of 4-NP in the spiked sediment samples from a reservoir and a polluted river were 111% with 4% RSD and 106% with 5% RSD, respectively. The perfect applicability of PLE for 4-NP was determined after testing it with spiked and aged samples. The extraction efficiency of the PLE was compared with conventional Soxhlet and bath ultrasonication extraction methods using the spiked sediment samples.