Fully automatic single-drop microextraction with one-setp extraction and derivatization and its application for rapid analysis of hydroxylated polycyclic aromatic hydrocarbons in seawaters

A fully automatic single-drop microextraction (SDME) coupled with gas chromatography/mass spectrometry (GC/MS) was developed for the determination of 12 hydroxylated metabolites of polycyclic aromatic hydrocarbons in seawaters. The derivatization reagent was added to the extraction solvent in order to realize one-step extraction and derivatization. High sensitivity of the method could be achieved after several parameters were optimized with the limit of detections (LODs) ranged from 0.33 to 7.50ngL^-1 and RSDs less than 15%. Recoveries ranging from 68% to 128% was observed, and the proposed method was more acceptable than solid phase microextraction (SPME) in term of high sensitive, accurate and inexpensive. Moreover, it was found that most of the analytes could be described by the mass transfer kinetics except for 9-OH-fluo, because the mass transfer rate of 9-OH-fluo was faster than its derivatization rate. Hence, the concentration of TMS derivative of 9-OH-fluo was ignored in this study as it was determined by the reaction rate. Finally, the proposed method was successfully applied to determine the hydroxylated PAHs in surface and bottom sea waters collected from the Pearl River Estuaries, respectively. Most of the hydroxylated PAHs could be detected with the total concentrations ranging from 0.0387 to 1.0741µgL^-1, and their spatial distribution was investigated by using spatial interpolation method of ordinary kriging in this study.