(MIDTERM) Other topics Flashcards
Electromagnetic radiation ranging between 400 cm-1 and 4000 cm-
1 (2500 and 20000 nm) is passed through a sample and is absorbed
by the bonds of the molecules in the sample causing them to stretch
or bend.
IR (Infrared) Spectrophotometry
❑ Qualitative fingerprint check for identity of raw materials
❑ Preliminary check for compound ID Can be used to characterize
samples in the solid and semi-solid states
❑ Used to detect polymorphs of drugs
Applications of IR Spectrophotometry
- Provides complex fingerprint which is unique to the compound
being examined. - Computer control of instruments
Strenghts of IR Spectrophotometry
❑ Rarely used as a quantitative technique.
❑ Usually can only detect gross impurities in
samples.
❑ Sample preparation requires a degree of skill.
❑ Lacks robustness
Limitations of IR Spectrophotometry
Atoms are thermally excited so that they emit light and the
radiation emitted is measured
AES (Atomic Emission Spectrophotometry)
- Quantification of alkali metals
- Determination of metallic impurities
Applications of AES
▹ Provides robust, cheap and selective method
Strengths of AES
▹ Only applicable to the determination of alkali and some alkaline
earth metals.
Limitations of AES
Atoms of a metal are volatilized in a flame and their absorption of a
narrow band of radiation produced by a hollow cathode lamp,
coated with the particular being determined, is measured
AAS (Atomic Absorption
Spectrophotometry)
More sensitive than AES.
Strengths of AAS
Determination of metal residues remaining from the manufacturing process in drugs.
Applications of AAS
- Only applicable to metallic elements.
- Each element requires a different hollow cathode lamp for its
determination.
Limitations of AAS
