Colorimeter

Colorimeter

A colorimeter is a device used for measuring colors or colorimetry. It can measure the absorbency of light waves. It measures the absorbance of different wavelengths of light in a solution. The device measures the intensity or concentration of the color that develops upon introducing a specific reagent into a solution. It can be used to measure the concentration of a known solute.

Different chemical substances absorb different wavelengths of light. When the concentration of the solute is higher, it absorbs more light at a specific wavelength. This is known as the Beer-Lambert law. This law states that the light absorption when passes through a medium are directly proportional to the concentration of the medium. In a colorimeter, a beam of light with a specific wavelength is passed through a solution via a series of lenses, which navigate the colored light to the measuring device. To ensure that the color of the products is of the best quality and level, a colorimeter is used.

There are two types of colorimeters: color densitometers, which measure the density of primary colors, and color photometers, which measure the color reflection and transmission. The color photometers are used for measuring the reflectance of color as well as the transmission.

Different parts

The most important parts of a colorimeter are:

  • a light source, which is usually an ordinary filament lamp
  • an aperture, which can be adjusted
  • a set of filters in different colors
  • a detector that measures the light which has passed through the solution

Filters

Different filters are used to select the wavelength of light which the solution absorbs the most. This makes the colorimeter more accurate. Solutions are usually placed in a glass or plastic cuvettes. The usual wavelengths used are between 400 and 700 nanometers. If it is necessary to use ultraviolet light (below 400 nanometers) then the lamp and filters must be changed.

Applications

The colorimeter is a device that is mainly used in industries and laboratories for analyzing the color quality of the products along with the color measurement. They are widely used to monitor the growth of a bacterial or yeast culture.