Organic Analysis Flashcards
What are the stages in mass spectrometry?
Vaporisation Ionisation Acceleration Deflection Detection
What is the molecular ion peak?
The peak with the highest M/Z ratio in he spectrum
How can you determine the relative molecular mass using a mass spectrum?
Use the molecular ion peak to determine he relative molecular mass
But watch out for the (M+1) peak caused by carbon 13 isotope
How can we use mass spectrometry to identify different individual isomers?
2 isomers will have the same molecular formulas and therefore the same molecular ion peak however they produce different fragmentation patterns.
Different fragment ions will produce different peaks
Why can we use infrared spectroscopy (IR) to identify molecules?
IR radiation can be absorbed by molecules
How can we make an IR spectrum?
- Bean of IR radiation is passed through the sample.
- Molecule of our sample will absorb some of these frequencies
- The bean that passes through is analysed
- Plot a graph of transmittance against frequency ( this is the IR spectrum)
- Analyse the spectra that are formed
What is the fingerprint region of an IR spectrum?
Region between 500 - 1500 cm^-1
Absorption’s always e caused mainly be bending and are therefore specific to each molecule (hence fingerprint)
Tris region can be used to identify the molecule.
What are the applications of IR spectroscopy?
Breathalyser
Air quality monitor
Forensics
What is chromatography?
A separation technique for identifying chemicals in a mixture.
What is the stationary phase in thin layer chromatography?
A thin piece of unreactive material and cover it in an absorbent chemical (eg aluminium oxide)
What is the mobile phase in thin layer chromatography?
Usually and organic solvent that will move in 1 direction up the thin. Layer
How do you calculate the Rf value?
Distance moved by the compound / distance moved by the solvent.
Rf values are always between 0-1
What is column chromatography?
A Column is packed with a solid and a solvent moves down the column
What is gas chromatography?
A column is packed with a solid or with a solid coated by a liquid and a gas is passed through the column under pressure at high temperatures