Chemometric optimization of hollow fiber-liquid phase microextraction for preconcentration of trace elements in diesel and gasoline prior to their ICP-OES determination

A hollow fiber-liquid phase microextraction (HF-LPME) method for the simultaneous extraction and preconcentration of Ag, Al, As, Mn and Ti as ammonium pyrrolidine dithiocarbamate (APDC) complexes in [C₆MIM][PF₆] ionic liquid are reported. Multivariate techniques such as 2⁴ factorial and Box-Behnken designs were used for the optimization of experimental parameters. Under optimized conditions, the limits of detection and quantification ranged from 0.04 to 0.09 and 0.15-0.29μgL^-1, respectively. The preconcentration factors of 150, 291, 112, 405, 367 for Ag, Al, As, Mn and Ti, respectively, were achieved. The precision of the HF-LPME method estimated as the relative standard deviation (RSD) for five replicate determinations of metal ions at a concentration of 10μgL^-1 was less than 5%. The HF-LPME method was verified by analysis of the target analytes in commercial diesel and gasoline samples. The accuracy of the proposed method was confirmed by performing standard addition method (spike recovery experiments, that is, spiking the samples with known amount of the standard). The recovery values (96-101%) indicated a satisfactory accuracy.