Should UV-Vis be used to Confirm the Quality of Ibuprofen?

Ibuprofen, a widely used medication for treating pain, fever, and inflammation, is an active pharmaceutical ingredient (API) whose quality must be rigorously controlled. The United States Pharmacopeia (USP) and European Pharmacopoeia (EP) have developed detailed written reports – referred to as monographs – that outline specific identification tests, procedures, and acceptance criteria to ensure the strength, quality, and purity of ibuprofen.

Spectrophotometric tests are crucial to confirming the identity and testing the purity of ibuprofen samples in pharmaceutical quality control laboratories, so these monographs contain detailed instructions utilizing a variety of analytical instrumentation used in the testing.  The various analytical techniques include infrared absorption spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, melting point analysis, and chromatography.

The spectrophotometric ibuprofen identification test according to the EP ibuprofen monograph requires measuring a test sample and comparing the ratios of its absorbance values to confirm they are within an acceptable range. We took a look at the use of UV-Vis spectrophotometers to perform the essential identification tests for ibuprofen as described in the USP and EP monographs, and have outlined below the tests we performed and the results.

What is UV-Vis

UV-Vis, or Ultraviolet-Visible Spectroscopy, is a non-destructive analytical technique used to measure the absorbance or reflectance of a sample in the ultraviolet and visible regions of the electromagnetic spectrum. The technique is commonly employed to determine the concentration of a substance in solution, analyze the purity of compounds, and study the electronic transitions in molecules.

In UV-Vis spectroscopy, a sample is exposed to light in the UV (typically 200-400 nm) and visible (typically 400-700 nm) wavelength ranges. The instrument measures the intensity of light before and after it passes through the sample. These intensities can be used to calculate absorbance as the loss of light intensity as it passes through a sample arises from the absorption of photons,. According to Beer-Lambert’s law, a linear relationship exists between absorbance and analyte concentration.

Testing with UV-Vis

The identification tests for ibuprofen were carried out using a UV-Vis spectrophotometer. The procedure involved comparing the absorbance spectra of a test sample of ibuprofen against a standard ibuprofen sample. The USP and EP monographs provide specific instructions on how these tests should be conducted.

1. USP Identification Test:

• The identity of the ibuprofen test sample was confirmed by comparing its absorbance spectrum to that of a standard ibuprofen sample.
• The absorbance peaks at specific wavelengths were matched to ensure the sample met the USP criteria.

1. EP Identification Test:

• The test involved visual inspection and comparison of absorbance ratios at designated wavelengths.
• The absorbance ratios of the test sample were compared to those specified in the EP monograph to confirm the sample’s identity.

Results:

The UV-Vis spectrophotometric tests successfully identified the ibuprofen test samples according to both USP and EP requirements. The absorbance spectra and ratios matched the criteria outlined in the respective monographs, confirming the identity and quality of the ibuprofen samples.

Conclusion:

UV-Vis spectrophotometers are essential analytical instruments for pharmaceutical quality control laboratories. They provide a reliable and efficient means of performing spectrophotometric identification tests for ibuprofen, as required by USP and EP monographs. The successful application of these tests ensures that ibuprofen samples conform to the stringent standards for strength, quality, and purity, thereby safeguarding public health.

Summary

UV-Vis spectrophotometry can play a critical role in pharmaceutical quality control, particularly in the identification and verification of ibuprofen samples. By adhering to the detailed procedures and acceptance criteria outlined in the USP and EP monographs, laboratories can ensure the integrity and efficacy of ibuprofen as a therapeutic agent.

For more specific information, download the application note: Spectrophotometric Analysis of Ibuprofen According to USP and EP Monographs.

References:

1. United States Pharmacopeia and National Formulary (USP 43-NF 38), Monographs, Ibuprofen.
2. European Pharmacopeia (EP 9.6), Monographs, Ibuprofen.

• Application note: Spectrophotometric Analysis of Ibuprofen According to USP and EP Monographs.