The gas chromatography process differs from other types of chromatography because it is gas, and the components are separated into vapours. This allows it to distinguish and identify smaller molecular weight compounds inside the gas phase. The sample is either liquid or gas which is then vaporized at the port for injection. The mobile phase in gas chromatography is a transporter gas, most often helium, because due to its molecular weight being low and its chemical inert. It is pressed, and the mobile phase is able to move the analyte along the column. The separation process is carried out using a column coated stationary phase.