Forensic chemistry, a branch of analytical chemistry uses a range of techniques in separation and identification of amino acids present in a protein and the sources of these proteins. Two such techniques are Gel Electrophoresis and High Performance Liquid Chromatography (HPLC). Both techniques are uses extensively in the separation of a mixture and analysing how it is done. These two techniques of separation can be compared based on how they separate samples, such as biological samples like blood and saliva and chemical compounds such as dyes. Minor comparisons between the two methods can be made based on cost, time and the practicality of each method. In addition to this the uses, importance and accuracy of each technique can prove to be pivotal in obtaining accurate forensic results.
HPLC is used when the separation of a mixture containing different compounds and elements is needed. HPLC works in two stages, a mobile stage and a stationary stage. HPLC functions on a pressure based system. Essentially a solvent is held in a reservoir, this being the mobile part because it moves. The solvent is generated to flow at a specific rate, usually millilitres/second; by a pressure pump. The sample which is to be separated is then injected into the solvent and is carried to the HPLC column. Here the stationary part is held and contains the material which can separate the sample. Separation occurs when the mobile stage moves over the stationary stage taking some components in the mixture along with it, each component moves at a different rate depending on how much it sticks to the stationary stage.
Electrophoresis is the technique where the motion of elements or compounds in an environment with a constant electrical field is monitored. In electrophoresis an electrical current initiates movement when it is run though the stationary stage. The stationary stage is the gel in which the mobile stage, the sample being separated, is injected into. The electrical current pulls ions from the mixture across the stationary phase in different amounts, and at different rates depending on the charge of the ion and the size of the molecular strand.
The cost of each technique coincides with is availability in different circumstances. While cost would not be an issue to major facilities; universities and forensic labs etc., it can often determine whether schools or smaller institutions can use them. Both gel electrophoresis and high pressure liquid chromatography require bought equipment in order to run samples for separation. HPLC can be more expensive as it requires more complex equipment, such as monitors and high-pressure pumps. Electrophoresis while requiring items such as power boxes and gel holding bays is usually more affordable than HPLC and as a result can be used in schools. What may more commonly be found as a use of chromatography in schools is an alternate chromatography technique which is, paper chromatography. This simply requires paper, water and dyes which are all easily accessible and cheap. Thanks for Reading ~Check out my other posts: 
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