Quantitative evaluation of chromatograms from scanned thin-layer chromatography plates

Abstract

This paper presents the first study of quantitative evaluation of thin layer chromatographic (TLC) plates by using a conventional scanner device and applying MATLAB program with Image Processing Toolbox. The program was used to quantify the colored image of developed thin layer chromatography plate which was then converted into gray scale with 256 levels of gray. Afterwards the desired threshold was chosen in order to transform the image into black and white, to determine the desired area, the borders and the coordinates of all spots on the plate. Finally, the density of the gray area was calculated for each object. Experiments showed that the obtained results of density and area of gray spot surfaces were proportional to the concentration values of analytes, covering a high concentration range with a linear correlation between program output and concentration of model ions. As model samples several different metal ions (namely cobalt, chromium and copper) were quantified on cellulose layer with the practical limits of error between 1 and 2 %. In addition, inter and intra plate precision, repeatability, relative standard deviation (RSD) and linearity were determined for all metal ions for regular and irregular shapes of spots.