Mass Spectrometry
1
,• All chemical substances are combinations of atoms.
• Atoms of different elements have different masses (H =
1, C = 12, O = 16, S = 32, etc.)
• An element is a substance that cannot be broken down
into a simpler species by chemical means - has a unique
atomic number corresponding to the number of protons
in the nucleus
• Different atoms combine in different ways to form
molecular sub-units called functional groups. 2
, • Mass of each group is the combined mass of the atoms
forming the group (often unique)
• e.g. phenyl (C6H5) mass = 77, methyl (CH3) mass = 15,
etc.
• So:- If you break molecule up into constituent groups
and measure the mass of the individual fragments (using
MS) - Can determine what groups are present in the
original molecule and how they are combined together.
3
1
,• All chemical substances are combinations of atoms.
• Atoms of different elements have different masses (H =
1, C = 12, O = 16, S = 32, etc.)
• An element is a substance that cannot be broken down
into a simpler species by chemical means - has a unique
atomic number corresponding to the number of protons
in the nucleus
• Different atoms combine in different ways to form
molecular sub-units called functional groups. 2
, • Mass of each group is the combined mass of the atoms
forming the group (often unique)
• e.g. phenyl (C6H5) mass = 77, methyl (CH3) mass = 15,
etc.
• So:- If you break molecule up into constituent groups
and measure the mass of the individual fragments (using
MS) - Can determine what groups are present in the
original molecule and how they are combined together.
3
