Gas chromatography mass spectrometry

Review the main parts of the GCMS instrument including the autosampler, column oven, column, mass spectrometer, and gas cylinder. Understand that a computer controls the instrument and collects data.

Learn how the autosampler rapidly introduces samples through a numbered sample tray and injection needle. The needle rinses between injections and withdraws samples at set volumes for automatic injection.

Close the insulated oven door and maintain the column at required temperature. Understand that temperature control affects molecule elution time and can be programmed for temperature gradients.

Trace the sample path from the inlet where it enters the column through the stationary phase, to the outlet where it exits toward the detector. The mobile phase (inert gas) carries the sample through the entire system.

The mass spectrometer uses a quadrupole detector with four rods and alternating voltages to separate ions. Only selected mass-to-charge values follow stable paths through the rods and are counted by abundance.

Review the software output showing a chromatogram (relative abundance vs. time) with peaks indicating when molecules elute from the column. Examine the mass spectrum (relative abundance vs. mass-to-charge ratio) below showing detected ion masses for each peak.