How To Use A Spectrophotometer To Detect The Concentration Of A Solute In A Chemical Solution?

Reviewed by Anurag Mishra (Sr. Technical Consultant)

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Chemical solutions are widely used in different industries. They are used for the preparation of different chemical concoctions that are further used in different processes. The concentration of the solutes in the solutions is one of the major factors that has a great impact on the properties and behavior of the chemical solution. Even a slight change in the concentration of the solutes can bring vast changes in the behavior of the entire solution. This is why the chemical solutions or closely analyzed for studying the concentration of different solutes in a particular solution.


One of the best ways to detect the exact concentrations of the solutes, the solution can be analyzed with the help of the process of spectrophotometry. The Spectrophotometry works on the principle that the light is a form of electromagnetic waves that can travel through different mediums with different levels of absorption and transmittance. The electromagnetic waves with a wavelength range of 400 nm to 740 nm are detected as the visible light spectrum. The different wavelengths of light contribute to a different color which is detected by our eyes. In the process of spectrophotometry, there is a spectrum of light passed through the specimen and a detector is placed on the other end of the specimen which receives the light transmitted through the specimen. By analyzing the amount of light transmitted through the specimen, one can detect how much light is absorbed by the sample which eventually gives the information about the chemical properties of the specimen.

Portable Spectrophotometer

The portable spectrophotometer is an instrument that is used for performing the experiment of spectrophotometry. The instrument is capable sending a single wavelength of light through a specimen and detect the exact amount of that light which transmits through the specimen. The Portable spectrophotometer not only works with the visible light but also can work with the other wavelengths such as UV rays and infrared rays which make it usable for a wide variety of specimen.

Testing the concentration of the solutes in a solution

When a solution is to be tested through a spectrophotometer then, first of all, a wavelength of light is passed through a blank that contains only the solvent and no traces of the solutes in it. After this, the same wavelength of light is passed through a solution with both solvents and solutes. This gives the percent transmittance at that particular wavelength. The Percent transmittance can be expressed by the expression:

Apart from transmittance, the absorbance should also be found to get the exact concentration of the solutes in the solution. The Absorbance of the solution can be given as the amount of light that has been absorbed by the solution. The expression for the Absorbance can be given as:

With the help of accurate spectrophotometry, it becomes easy to calculate the concentration of the solutes and ensure that the solutions are prepared with exact molarity and chemical concentration which eventually leads to results of the desired accuracy.

The Testronix Portable spectrophotometers are one of the best instruments that are used widely in different laboratories to perform the process of spectrophotometry with great accuracy and simplicity.

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