GC-MS: A Gas Chromatography (GC) instrument coupled to a Mass Spectrometer (MS).

Gas Chromatography:

• Samples are injected onto a chromatography column and swept through by a constant flow of gas
• As the compounds travel through the column they become caught up in the mesh
• Different metabolites interact with this mesh in different ways which affects their movement along the column and allows them to be separated
• This makes the metabolites easier to detect by mass spectrometry since they are not all released (eluted) at the same time

This technique is very useful for analysing small molecules.

• It can be used to identify fatty acids, amino acids, organic acids and sugars in urine and blood and is used by clinicians to diagnose metabolic disorders
• e.g. phenylketonuria (PKU) diagnosis involves the measurement of levels of phenylalanine and tyrosine amino acids