Study on Impact Factors of Affecting Liquid-liquid Extraction Efficiency of 12 Nonylphenol Isomers

Nonylphenol(NP) which has a strong estrogenic effect, is an emerging persistent organic pollutant (POPs). In recent years, NP has caused widespread attention for its pollution in water at home and abroad. Hence, the extraction of NP in water samples is particularly important. However, the study about extraction efficiency of NP was aimed at the total amount, and single isomers were seldom studied. Liquid-liquid extraction, as the most traditional and easiest method for NP's extraction, was chosen in this study for its simple and cheap equipment. Factors which affect the extraction efficiency of 12 NP isomers were studied by Gas Chromatography-Mass Spectrometry (GC-MS). To improve the extraction efficiency of NP, factors such as the type and dosage of extraction solvent, dosage of NaCl and sample's pH were optimized. Results show that the extraction efficiency of 12 isomers was highest when 60 mL methylene chloride was selected as the extraction agent, and pH<1 and 60 g NaCl was added in the water samples. The extraction rates for 12 NP isomers were in the range 88.7%-101.2% with RSDs (n=3) of 10.3%-13.6% and detection limits of 9.0-41.4 ng/L. The optimized method for 12 NP isomers can achieve an expected extraction effect within 70%-130% by USEPA, and has been used successfully for the extraction of NP in water samples.