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Measuring Chemicals Using Spectrophotometer

Photo by Artem Podrez

The following steps must be performed in order to use a spectrophotometer to measure a chemical compound’s concentration:

Sample Preparation

Dissolve the chemical compound into a solvent solution. The solution must be clean and free of any contaminants that might interfere with the measurement.

Select The Appropriate Wavelength

Identify the wavelength of light that the substance absorbs, also known as its maximum absorbance. You can find this information in a reference book or by using a UV-Vis spectral database. Choose a wavelength that matches the compound’s maximum absorbance.


Create a set of standard solutions containing the substance in known quantities. Once that is done, use the spectrophotometer to measure each solution’s absorbance at the chosen wavelength. Plot a calibration curve by plotting the concentration of each standard solution on the x-axis and its corresponding absorbance on the y-axis.

Measure the sample

With the spectrophotometer, determine the sample solution’s absorbance at the chosen wavelength. Determine the chemical concentration in the sample using the calibration curve. You can do this by comparing the absorbance of the sample to the absorbance of the standard solutions and reading the concentration value from the calibration curve.

Additional Notes

It’s important to keep in mind that the precision of the spectrophotometer, the accuracy of the calibration, and the quality of the samples can affect how accurate the measurement is. To ensure accurate and reliable results, it’s essential to adhere to good laboratory procedures and follow the appropriate methods for quality control.