1. Mass Spectrometry(MS)

2. What does the mass spectrometer tell us? Very accurate determination of molecular mass of small compounds (or more accurately the mass/charge ratio) Sample is vapourised then ionised by knocking off e - Ion is accelerated through magnetic field The curvature of the path is a function of the strength of the magnetic field and the mass/charge ratio (m/z) The ionisation does cause fragmentation of the compound, giving a predictable set of signals

3. Let’s look at ethanol Known molecular mass of ethanol is 46 (12×2 + 16×1 + 1×6) A fragment generated by the loss of the –CH 3  46 – 15 = 31 A fragment generated by the loss of the –OH  46 – 17 = 29 + + + + +