Standardization of Dispersive Liquid-Liquid Microextraction for Determination of ۱۶ Polycyclic Aromatic Hydrocarbons in Water Samples

In this study, Dispersive liquid-liquid microextraction (DLLME) combined with High performance liquid chromatography-Multichannel Fluorescence detector (HPLC-FLD) as a simple, fast and inexpensive method have been optimized in order to develop a standard method for determination of polycyclic aromatic hydrocarbons (PAHs) in water samples. In the optimum condition, ۶mL of extraction mixture contains aceton (disperser solvet) and dichloroethylene (extractor solvent) (۵۰:۱) are rapidly injected into the sample (۳۰.۰۰ mL) containing ۱ mL of NaCl solution (۱۰ w/v%). Therefore, a cloudy۲solution is formed. After centrifuging, the sedimented phase were transferred into a vial and evaporated at ۳۵°C under nitrogen atmosphere. Thereafter, ۲۰۰ μL acetonitrile is added to the vial, the obtained solution evaluated using HPLC-FLD. Under the optimum condition, it was possible to measure ۱۴ PAHs compounds. The linear ranges for most compounds are in the range ۰.۵-۰.۵ μgL-۱.The recovery rate is between ۶۵% -۹۴% and the quantitative detection limit (LOQ) is in the range of ۰.۰۰۳-۰.۱۲ μgL-۱. The relative standard deviation (RSD%) in the concentration of ۰.۷ μgL-۱ of PAHs were ۴.۵-۷.۷% (n=۳). The method was validated by simultaneous testing of a spiked sample with the standard method (ISIRI ۹۳۸۷-۲) and the mean results were compared using t-test. The extraction method was also coupled with gas chromatography-Mass spectrometer (GC-MS) to evaluate its performance and robustness. Finally, the optimized method was used to measure the concentration levels of PAHs in ۴۰ water samples. The proposed procedure is can be developed to determine PAHs in other matrices. In order to standardization the method, its precision including repeatability and reproducibility, accuracy and robustness were tested.