Principle:
Infrared spectroscopy involves the interaction of infrared light with molecules, leading to vibrations of atoms within those molecules.
How it works:
1. Absorption:
When infrared radiation passes through a sample, specific frequencies of the radiation are absorbed by the sample, causing vibrational transitions in the molecular bonds (like stretching or bending).
2. Spectrum Generation:
The remaining radiation is passed onto a detector.
A spectrum is generated that shows the intensity of the radiation against its frequency or wavelength.
The regions of the infrared spectrum where the sample absorbs radiation are indicative of the type of chemical bonds present.
3. Fingerprinting:
Each molecule has its unique infrared absorption pattern (or 'fingerprint'). This is because different bonds will vibrate at different frequencies.
For instance, C-H, N-H, and O-H bonds each have distinct absorptions in the infrared spectrum.
Pharmaceutical Application:
1. Identification:
IR spectroscopy can be used to identify and verify the chemical makeup of a pharmaceutical compound, ensuring its purity and consistency.
2. Quantitative Analysis:
Besides qualitative analysis, the method can also quantify the amount of a specific compound in a sample.
3. Formulation Analysis:
It's employed to examine drug formulations to ensure the right ingredients are present and that there aren’t any unwanted impurities.
4. Physical State Determination:
It can also provide information about the physical state of drug compounds (for example, if a drug is in its crystalline or amorphous form).