Water Quality Photometers and Colorimeters

Water quality photometers and colorimeters are ion-specific, computer-interfaced probes that are designed to determine the concentration of a solution from its color intensity. The color of a solution may be inherent, or derived by adding a reagent. Monochromatic light from an LED or other light source passes through a cuvette that contains a solution sample. Some of the incoming light is absorbed by the solution. As a result, light of a lower intensity strikes a photodiode. With water quality photometers and colorimeters, the amount of light that penetrates a solution is known as transmittance, which can be expressed as the ratio of the intensity of the transmitted light to the initial intensity of the light beam.