Gas Chromatography-Mass Spectrometry (GC/MS)

GC separation occurs in the gas phase, which implies that samples must be prepared before analysis. This would involve chemical digestion and modification (derivatisation) to produce a liquid solution containing volatile compounds. Sometimes sample preparation can be complicated and time consuming.

Typical use of GC/MS includes the analysis of organic materials such as food remains from archaeological objects, binding media (oils, proteins, carbohydrates) from paintings and conservation materials (resins, wax, glue).

Inside the GC, the sample is volatilized and flows through a column in a stream of inert carrier gas (helium or hydrogen). The separation which occurs is based on the boiling points of the volatile compounds and their interactions with the material coating the column. The time a compound needs to pass through the column (retention time) is a specific parameter used for identification, in combination with the information subsequently derived from MS. 

The power of GC/MS to separate, characterise and quantify complex mixtures of organic compounds with high sensitivity has made it an indispensable analytical tool to address detailed questions about the chemical constituents of museum artefacts and materials used in conservation. GC/MS is often used after initial analysis by for example, FTIR or Raman spectroscopy.

Instrument specifications
SciCult-KHM is equipped with a Shimadzu single quadrupole GCMS-QP2010 SE gas chromatograph-mass spectrometer. Additionally, pure compounds, separated by other available techniques (HPLC, TLC, flash chromatography) can be analysed by using direct sample injection (DI-MS) where a sample is injected directly into the mass spectrometer without passing through the GC.