Indium determination and preconcentration using fiber optic linear array detection spectrometry combined with dispersive liquid-liquid micro extraction

A new method for the preconcentration and determination of indium was developed using fiber optic linear array detection spectroscopy (FO-LADS) combined with liquid-liquid microextraction (DLLME). DLLME was performed with rapid injection of a mixture containing ethanol (disperser solvent) and chloroform (extraction solvent) into water sample containing indium after complex formation using 1-(2-pyridylazo)-2-naphthol (PAN) reagent that resulted in the formation of a cloudy solution. After centrifuging, fine droplets of chloroform, which were dispersed among the solution and extracted In-PAN complex, sedimented at the bottom of the conical test tube. The concentration of enriched analyte in the sedimented phase was determined by FO-LADS. The optimized method exhibited a good linearity (R ² = 0.993) over the studied range (2–300 μg/L), illustrating a satisfactory precision level with standard deviation (RSD, n = 5) lower than 4%. The detection limit was 0.3 μg/L, and the enhancement factor of 160 was obtained. The proposed method was compared with other methods and successfully applied to the analysis of several real and standard samples with satisfactory results.