Effect of solution concentration on the UV-vis spectroscopy measured oxidation state of polyaniline base

The effect of the concentration of polyaniline (PANI) base in dimethyl formamide (DMF) solution on the UV-vis spectroscopy determined oxidation state of PANI is presented. It is shown for the first time that the UV-vis spectra determined oxidation state of the same PANI decreased with increasing concentration of the testing solution in the UV-vis measurement, and showed also a fluctuation with the testing time interval. Together with the analysis of the Lambert-Beer law, it was concluded that only when the testing concentration was specified, could the UV-vis spectra be used to illuminate or differentiate the oxidation state of PANI base.