Amirul Aiman Bin Fadzliniza, B. Optom

Student, Management and Science University, Malaysia



The science of colour measurement is known as colorimetry. Developed by Helmholtz, Maxwell, and Young, they hypothesised the colour perception of humans through the principles of additive as well as subtractive colour mixing.


The colorimeter is one of the instruments used in colorimetry to measure the transmittance and absorbance of light passing through a liquid sample. The device usually measures a known concentration of a solute with the help of Beer-Lambert law. There are three main components in a colorimeter which include a light source, a cuvette containing the sample, and a photocell for detection of the light that passes through the solution. The result may be displayed by an analogue or digital metre depending on the type of colorimeters used (Iqbal, 2019). The device also has a wide range of applications across chemical and biological fields.

Figure 1: Colorimeter (Noh et al., 2020; Santos et al., 2006)             

Principles of Colorimetry

To describe illumination, each visible spectrum of wavelength has its own relative intensity which is known as S(λ) light source or the spectral power distribution. Next, an object being reflected by incident light is described as R(λ), or reflectance spectrum. From there, we get light intensity I(λ) entering our eye because of these combined variables. These three variables can be used to specify the colour trio for us to obtain colour specificity and measurement. In other words, it is the measurement of the concentration of a certain compound (solute) in a coloured solution (solvent) in terms of chemical analysis (Niall, 2017). In the modern world, people frequently need to quantify the quantity of a specific component in a combination or the concentration of a solution during scientific activity. The trick is to determine the colour differences between various combinations and their absolute values. This is more instructive and scientifically valuable than relying on subjective judgments like the colour of the solution.

Furthermore, from a mathematical perspective, colourimetry is highly associated with the Beer-Lambert law (Arnold, 2013):

Beer-Lambert law shows the relation of the attenuation of visible light through a solution and the property of the solution, hence can also be defined as the absorbance and transmittance of light. With this law, in a colorimeter, a beam of wavelength-known light will be used as a standard to compare with the tested light (Sulkowitch, 1932). A graph with concentration against the absorbance will be plotted as a result.

Figure 2: Graph representation of Beer-Lambert law (Chaple et al., 2010; Al-Sabagh et al., 2014)


With the ability to test for light absorbance, the colorimetry is widely used in industries such as biochemistry and laboratory industries. With this, concentrations of solution can be easily measured (Critchley, 2017). Furthermore, measurements such as the analysis of organic fluid like blood, water and food can also be done easily. For application in daily life, the colorimetry serves as a guide for humans to prepare objects with suit colour such as matching outfits and suitable design (Gilchrist & Nobbs, 2017).


Colorimetry is a method that measures the concentration of a solution with the usage of Beer-Lambert Law. The machine that undergoes the measurement is known as the colorimeter. The application of colorimetry is mostly associated with the biochemistry industry.


I want to acknowledge my friends and classmates Zarif Irsyad bin Rosli & Heng Zhe Xu for equal contribution in this writing.



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