Colorimeters use a light source of a particular wavelength, a color-changing, colorimetry reagent, and a light detector to determine the concentration of a particular substance, usually in an aqueous or water-based sample. After mixing the sample with a specific color-changing reagent, the sample is place within the sample chamber of the colorimeter, where light of a specific wavelength is passed through it. The desired substance’s concentration measurement will react with the reagent to change the color of the sample. The concentration of the parameter is proportionate to color change intensity. Since different chemical substances absorb different visual light frequencies, the detector can determine the absorbance of the light passed through the sample based on the intensity of the sample color. We stock both single-parameter and multi-parameter colorimeters.