Determination of Chromium and Iron Using Digital Image-based Colorimetry

Abstract

Recent advance in digital imaging has made a high-resolution photo produced from digital camera more affordable. The use of digital images comprises current opportunity to develop fast and low-cost colorimetric detections for quantitative chemical analysis. The method employs prime color space RGB (red–green–blue) with individual values varying from 0 to 255. RGB data was extracted from a square-homogenous cropped digital images using Matlab software (Mathworks Inc., USA) to construct calibration curve in quantitative determination. We compare two different methods to determine the concentration of chromium (Cr) and iron (Fe). The first method is based on simple linear regression (SLR) of individual color R, G or B. The second method is based on partial least square (PLS) of all three colors R, G and B. Accuracy of the method was validated using UV-visible spectrophotometry as a reference method. We found that accuracy of the method was better than 2.5% with precision less than 1.4% for both chromium and iron.