HPLC vs GC
HPLC and GC are both methods of separation of compounds from a mixture. Whereas HPLC applies to constituents that are fluids, GC is used when the compounds are gaseous or can be vaporized during separation process. Both have the same underlying principle of heavy molecules flowing slower than lighter ones. While HPLC refers to High Pressure Liquid Chromatography, GC is simply Gas Chromatography. This article will highlight the differences between these two separation techniques.
The technique of HPLC is made heavy use of in analytical chemistry to identify and analyze the individual components of a mixture. In HPLC, columns and high pressure are used. High pressure ensures movement of constituents in a mobile phase. It also moves the analyte in a densely packed column. Smaller particle size helps in increasing the density of the constituents that helps in better separation when columns of shorter length are used.
Gas Chromatography on the other hand is mainly used to check the purity of a substance, and in some cases, also helps in identifying a substance. There are two phases, the mobile, and the stationary phase in the process. In the mobile phase, the carrier is an inert gas such as helium. Sometimes, nitrogen is used as it is unreactive. The stationary phase involves using a polymer or a layer of liquid on an inert solid base.
What is the difference between HPLC and GC?
The major difference between GC and HPLC lies in the phases used. While in GC, compounds of a mixture are separated using a liquid (stationary) phase and a gas (mobile) phase, in case of HPLC the stationary phase is a solid while liquids make up mobile phase. Another difference lies in temperature control during the process. In GC, there is an oven to contain the column consisting of gas phase and it can control the temperatures when the gases are passing through the column. On the other hand, there is no such provision of temperature control in HPLC. The last difference pertains to the concentration of the compounds. In GC, it is the vapor pressure of the gases that decide the concentration of compounds whereas it is possible to increase or decrease the concentration of the compounds in HPLC.