Colorimetric polymer sensor for determination of chromium (VI): Comparison of estimation methods of the visible color changes

The paper describes an application of a kind of optical analytical method, digital color analysis (DCA), using colorimetric polymethacrylate sensors (optodes) in order to determine Cr (VI). The optodes are made of optically transparent polymethacrylate matrix (PMM) with 1.5- diphenylcarbazide immobilized. The developed optode can be used in determination of the anlytes using solid-phase spectrophotometry and calculating color coordinates as functions of absorbance spectra. Also color coordinates can be represented as basic color (e.g. RGB) data after the optode image digitizing. Then one can determine the content of an analyte in a sample by an appropriate color difference calculated on these coordinates. Experimental results of Cr (VI) determination show that the DCA characteristics of accuracy and precision are comparable with those of the solid phase spectrophotometry.