<p>The main objective of this work is to introduce “image scanning densitometry” for the elimination of drawbacks of the spectrometric methods, which are conventionally used for analysis of metal ions in aqueous samples. This method is beneficial because a small amount of analyte was used for toxicological chemical analysis in medical diagnostics and environmental monitoring along with its portable nature for on-spot analysis by integrating AI technology with conventional methods. By using this method, colorimetric reactions are performed on TLC plates and results are quantified by digitizing the area of spots by using image scanning devices and specially developed software. The analyte concentration is proportional to the RGB (red, green, blue) color densities of the quantified spots. The raw color densities of the spots were transformed by using Kubelka–Munk transformation in results, which give information about the different dynamic ranges. Different metals, such as nickel (II), chromium (VI), and iron (II), were quantified by using their aqueous samples for monitoring toxic contaminants of water streams. The detection limits are 3.8, 3.94, and 6.78 ppm for Cr(VI), Ni(II), and Fe(II) correspondingly.</p> Graphical Abstract <p></p>