Laboratory Equipment & Services Information System by Centralized Laboratory Management Office (CeLMO)

A colorimeter is a device used to measure the absorbance or transmittance of light by a sample at a particular wavelength, typically within the visible spectrum. It is commonly employed in various scientific fields, including chemistry, biochemistry, environmental science, and food science, among others.

Here's a breakdown of its key components and how it operates: Light Source: Colorimeters typically employ a light source that emits light of a specific wavelength or range of wavelengths. This light passes through the sample being analyzed. Filters: Colorimeters use filters to isolate the desired wavelength of light for analysis. Different filters can be used to select different wavelengths within the visible spectrum. Sample Holder or Cuvette: The sample holder, often called a cuvette, is a transparent container where the sample is placed for analysis. It is designed to allow the light to pass through the sample evenly. Photodetector: Positioned opposite the light source, a photodetector detects the intensity of light that passes through the sample. This can be a photodiode or a photomultiplier tube, depending on the sensitivity and precision required. Display and Controls: Colorimeters typically feature a display screen and controls for setting parameters such as wavelength, calibration, and measurement mode. Some may also have options for data storage and analysis. Calibration: Before use, a colorimeter needs to be calibrated using standard solutions of known absorbance or transmittance values. This ensures accurate measurements. Measurement: Once calibrated, the colorimeter is ready to measure the absorbance or transmittance of the sample. The sample is placed in the cuvette, inserted into the colorimeter, and the appropriate wavelength is selected. The device then measures the intensity of light passing through the sample. Data Analysis: The measured absorbance or transmittance values can be used to quantify the concentration of a substance in the sample, based on the Beer-Lambert law, which relates absorbance to concentration.

Colorimeters are widely used in laboratories for various applications, such as determining the concentration of a substance in a solution, analyzing the color of a solution for quality control purposes, or monitoring chemical reactions in real-time. They offer a quick, accurate, and relatively simple method for quantitative analysis of substances based on their optical properties.