Flashcards in 2. Analytical techniques Deck (10):
What does infrared spectroscopy do?
Infrared is directed through a sample and around it into a detector. Bonds in the sample will absorb different wavelengths(frequencies) , due to their uniquie vibrations. by comparing the two paths of infrared you will fine which frequencies were absorbed.
This indicates the presence of functional groups. with specific absorption peaks.
Samples specta can be compared with know specta in a database, for use in finding if samples of a drug are pure etc.
Which peak is very broad?
O-H in carboxillic acids.
USes of mass spectrometry
identify unknown compounds
determine isotope abundance
to gain information on the structure.
how does a mass spectrometer work?
a sample is placed in the tube.
e-, neurons or alpha particles are fired at it
this ionizes the sample.
they get propelled into the mass analyses the other end is -ve
mass is based off the time taken.
How is a mass spectrometer used to detect isotopes?
multiple peaks at the same area, their proportions tell you there proportions in the sample.
What is a molecular ion?
is the positive ion formed in mass spectrometer when a molecule loses an e-.
what is fragmentation?
its the process in mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragment ion.
What causes fragmentation?
excess energy from the ionization, causes bonds to vibrate , which weakens them and they break.
how do you use the fragmentation pattern?
each organic molecule has a unique fragmentation pattern, which can be looked up in a data base.