Optimizing of microfunnel-supported liquid-phase microextraction for the extraction of chlorophenoxyacetic acids in seawater samples

In this study, microfunnel-supported liquid-phase microextraction method (MF-LPME) was optimized and applied for the determination of some chlorophenoxyacetic acids (CPAAs) from natural water samples. The extraction was performed with 540 μL toluene which was retained at the surface of the sample solution using an upside down microfunnel. After the extraction, toluene was moved into the narrow stem of the microfunnel by pushing the device inside the sample. Then, using a microsyringe, it was transferred into micro vial followed by evaporation using a gentle stream of nitrogen. The residual re-dissolved into 50 μL acetonitrile, diluted to 100 μL with deionized water and analyzed applying a high performance liquid chromatography equipped with a UV detector (HPLC-UV). Central composite design (CCD) was used for the optimization of factors influencing the extraction. Under the optimized conditions, the limits of detection were 0.42 and 0.43 ng mL-1 for 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA), respectively. Preconcentration factors of 66 and 80 were obtained for 2,4-D and MCPA, respectively. The precision of the technique was evaluated in terms of repeatability which was less than 11.1% (n=5). The applicability of the proposed method was evaluated by the extraction and determination of CPAAs from some natural water samples.