Gas Chromatograph  Mass Spectrophotometer (GC-MS)

A gas chromatograph is an apparatus which can separate solvents. A liquid or liquid mixture is injected in the GC and the sample starts to travel a long distance of dozens of meters through a column in the apparatus. At the end the solvents appear one by one, the solvent with the lowest boiling point first, the solvent with the highest boiling point last. The affinity with the coating in the column is the main factor for the separation of solvents.

The components then enter the mass spectrophotometer which can identify all different (fragments of) components. We obtain a qualitative analysis. A quantitative analysis of the solvents can be done using a calibration line, obtained by injection of known concentrations of the components involved.

This method is used often to determine the VOC content according to ISO 11890-2 or EPA 24, or to distinguish solvent which are within or without the VOC definition.

The method can also be used for PAH (Polycyclic Aromatic Hydrocarbons), often present in old coal tar paint layers. Here we can determine among others the 16 PAH according to EPA.