Application of Colorimeter in Pharmaceutical Industry

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2022-03-06

Application of Colorimeter in Pharmaceutical Industry

The color of a medicine solution is an objective representation of the intrinsic quality of the medicine, and its difference from the specified color can to some extent reflect the purity of the medicine. 

Pharmacopoeias of various countries use it as an important inspection item for drug quality control, so colorimeters also play a crucial role in the process of medicine quality testing.

In the past, the color of solutions was generally compared with standard colorimetric solutions using manual visual inspection. 

However, for solutions with colors similar to standard solutions, it is difficult to determine them with the naked eye. 

Later, more advanced colorimeters were used in medicine to control detection. 

By accurately measuring the color difference between medicine solutions, standard colorimetric solutions, and water, the color of medicine solutions can be compared and described accurately and quantitatively, thereby controlling the quality of medicine.

The working principle of a colorimeter is simply to simulate the visual system of the human eye. 

Using the internal analog integrator optical system of the instrument, the three stimulus values of spectral data are integrated to obtain the expression of color data, 

thereby calculating the brightness index L *, chromaticity index a *, b * values, and the color difference of contrast chromaticity. 

When using the instrument method to compare the color of the test sample with its specified standard colorimetric solution, 

the parameter to be compared is the difference between the color of the blank control solution and the color of the test solution or its specified standard colorimetric solution in a uniform color space. 

Using instrumental methods to determine color not only enables accurate and quantitative measurement of color and color difference, 

but also is more scientific and objective than visual measurement, and does not change with time, location, or personnel.