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How does colorimetry detect mercury in a sample?

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Periodic table — zinc group element Modern version of the periodic table of the elements (printable).

Colorimetry detects mercury in a sample by measuring the intensity of the color produced when the sample reacts with a specific reagent, typically dithizone.1

This process relies on the principles of colorimetry, which determines the concentration of a substance based on how it absorbs light. By comparing the intensity of the color generated by the reaction in the unknown sample against the intensity produced by the same treatment of known amounts of mercury, analysts can determine the concentration of mercury present.21

This method is grounded in Beer’s law, which establishes a relationship between the concentration of an absorbing substance and the amount of light it absorbs. While colorimetry has been a standard analytical technique for zinc group elements, it is increasingly being replaced in modern practice by more rapid and accurate methods such as atomic absorption spectroscopy.21