In addition to the mass spectrometer and gas chromatograph, the GCMS has one other instrument it will use for analysis of Titan's atmosphere: an enrichment cell (pictured to the right). The enrichment cell is a separate instrument from the gas chromatograph and mass spectrometer that uses the mass spectrometer's detector to analyze its samples.
An enrichment cell is essentially a small container coated with an absorbent material. The material is chosen so that selected chemical components will stick to its surface. In the GCMS enrichment cell, the absorbent material is carbon.
Organics - the carbon-containing compounds scientists are interested in studying in Titan's atmosphere - typically stick quite well in an enrichment cell. However, to help scientists obtain the largest sample possible, the enrichment cell contains a rare gas cell. The purpose of the rare gas cell is to pull in a larger gas sample. Whatever compounds do not stick to the enrichment cell pass into the rare gas cell. This way, scientists make the most of their sample.
The rare gas sample is processed first. Once a sample has been taken in, a getter pump is then used to remove the majority component of the sample. In Titan's atmosphere, the majority component is nitrogen. The pump will also remove the reactive components, such as water and hydrocarbons. Thus, the remaining material inside the rare gas cell will be non-reactive components - the trace gases. After the pumping, the rare gas cell sample is let into the mass spectrometer for analysis.
While the instrument is processing the rare gas cell sample, the heaters to the enrichment cell have been turned on. Heating the enrichment cell sample releases the compounds captured on its walls. Once this process is complete, the enrichment cell sample is sent into the mass spectrometer for analysis.