Introduction to Analysis [Greenland] Flashcards
List 3 purposes of pharmaceutical analysis
To identify:
The active and other components in a formulation
The product from a reaction
The metabolites after administering a drug
Define: Accuracy
Closeness to a standard or true value
Define: Precision
Closeness of a series of measurements
What is the British Pharmacopoeia?
Provides minimum pharmacopoeial standards of medicines for human and animal use
Contains over 3000 monographs
Compliance with pharmacopoeial standards assures the quality of the pharmaceutical compound
Provides a level of protection for public health
Define: Polymorph
Crystal forms containing the same chemical compound differing arrangements and/or conformations in the crystal lattice
The different crystals may have differing physical properties (e.g. solubility, mp)
Explain the process of thin layer chromatography (TLC)
Performed on a glass or aluminium plate coated with silica (the stationary phase)
The dilute sample (a few mg/ml) is spotted onto the TLC plate
The plate is placed in a sealed container with a solvent (the eluent) and the eluent is drawn up the plate by capillary action
The time that the analyte resides in the eluent or in the silica depends on the structure of the compound
The lower the interaction of the compound with the silica, the more time it resides in the eluent and so the higher up the plate the sample runs compared to the distance the solvent has moved
The position of the solvent front at the end of the procedure is marked and the position of the sample is identified by staining or visualised using a UV lamp
The ratio of the position of the sample spot to the solvent front is calculated = the Rf value
Different compounds interact differently with the stationary phase and eluent so exhibit different Rf values
When is UV/vis spectroscopy useful?
Its spectra can be compared to an authentic sample of a compound
Useful for analysing how much of compound is in a given solution (concentration) - the intensity of the absorption is proportional to the quantity of sample in solution
How does infra-red spectroscopy work?
A sample is exposed to a range of IR frequencies
The intensity of the radiation at each frequency is measured after passing through the sample
How does mass spectrometry work?
The sample is ionised = either positively or negatively charged
The sample is subject to an electric field which imposes a forced on the ion
The ion accelerates in the field at a rate proportional to its charge and inversely to its mass
The time taken for the ion to cover a known distance is measured and converted to mass
How does X-Ray analysis work?
A beam of x-rays is directed at the sample
The x-rays pass through and they scatter by interacting with electrons in the sample
By measuring where the x-rays are scattered to, it is possible to calculate where they were scattered from
= electron density map of sample
= used to show where the atoms in the sample are
What information about a molecule does mass spectrometry provide?
The mass of the molecule
What information about a molecule does IR spectroscopy provide?
The functional groups it contains
What information about a molecule does x-ray analysis provide?
How the molecules fit together in the solid state
What information about a molecule does NMR provide?
Number of protons
Number of carbon atoms
The chemical environments the atoms are in
