Instrumental Analysis Francis Aston
Analysing Mixtures Samples to be analysed are often mixtures of different compounds. Chemists have developed a technique called gaschromatography-mass spectrometry (GC-MS) to separate and identify components within a mixture.
RSC Video – click to start http://www.youtube.com/watch?v=08YWhLTjlfo
GC-MS GAS CHROMATOGRAPHYMASS SPECTROMETRY - separation - identification
How it works • A small amount of sample is injected into one end of the heated column, where it turns to vapour (gas)
How it works 2: The substance is carried by the carrier gas through the tube
How it works 3: The carrier gas carries the sample through the stationary phase (the liquid)
How it works 4: The detector records the arrival of each chemical from the column.
How it works 5: Each arrival registers as a peak of the chromatogram.
A MASS SPECTROMETRY DETECTOR ION SOURCE ANALYSER
What are the 4 stages? What are the 4 stages? 2 1 Ionisation Acceleration Deflection Detection 3 4
Mass Spectrums The parent or molecular ion peak refers to the molecular mass of the compound. It is always the last peak found on the spectrum. In this example, the molecular ion has a mass of 44. Propane- Mr=44 C3H8 (12x3) + (1x8) = 44 Mass/charge values