ABSTRACT
Colorimetric tests can be carried out to analyze any substance in the aqueous phase for which a color-forming reaction is known. Colorimetric methods are the most common and are widely employed in environmental wet analysis. Most anions, all metals, and many physical and aggregate properties can be determined by the colorimetric technique, which is fast and cost effective. Absorbance and transmittance are two important terms used in absorption measurement. The Beer's law exhibits a linear relationship between the absorbance of a solution to its path length and to its concentration. Beer's law applies only to monochromatic radiation, that is, light of one wavelength and not polychromatic radiation. The absorbance is measured by a spectrophotometer. The first step in any colorimetric analysis is to prepare a standard calibration curve, which is then treated with the color-forming reagent, the absorbance or transmittance of which is then measured.
