gas chromatography

what is the mobile phase of GC?

• carrier gas

• usually H2, N2, He

what is the stationary phase of GC?

SiO2

what is the analyte of GC?

injected through a septum into a heated part and evaporates, then moves through the column by carrier gas

what are the requirements of GC?

• molecules must be sufficiently small/volatile

• column is very long, but flow rate is very high

what is the most common GC?

capillary columns

what are the parameters governing capillary GC performance?

carrier gas flow and type:

• H/He most used: high flow rates

column temperature:

• most likely what you control

• gradient to increase temperature

• governed by how much interaction between analyte and stationary phase

• the lower the temperature, the better the resolution

column length:

• generally very long: allows for lower temperatures

column diameter:

• the smaller the better

what are some GC detectors?

• most common: flame ionization
• mass spectrometry