Liquid chromatography is a separation technique that is used to identify, quantify and purify individual components in a mixture. It is one of the most powerful tools in analytical chemistry and is one of the most commonly found instruments in the laboratory. In this technique, the mobile phase is a liquid.
Ion chromatography allows the separation of ions and polar molecules based on their interaction with a column of ion-exchange media. It can be used for almost any kind of charged molecule, including large proteins, small nucleotides and amino acids. It is very widely used for the determination of inorganic and organic cations and anions.
High Performance Liquid Chromatography (HPLC)
In high performance liquid chromatography (HPLC), the sample is forced by a liquid at high pressure through a column that is packed with a stationary phase. The mobile phase is the phase that moves in a definite direction, typically through a column to interact with the stationary phase.
Ultra High Performance Liquid Chromatography (UHPLC)
Ultra-high performance liquid chromatography (UHPLC) is a variant of HPLC, which uses smaller particles to enhance chromatographic performance, and requires higher pressures. In a similar way to HPLC, the water contaminants can negatively impact on results; however, due to the higher sensitivities of the UHPLC, this can be more extreme.
Impact of Water
Typically pure water (Type II) is used to prepare blanks, standards, eluents and is for sample pre-treatment; however, as gradient HPLC is capable of extremely low detection limits, the water requirement is more stringent and the highest quality is required.
Poor quality data such as shifting retention times, loss of resolution or ghost peaks could be an indication of contamination caused by organics, ions, bacteria or particulates.
Make sure that you are using the right water type for your application. Here are the requirements for liquid chromatography applications:
This Technical Note was written by ELGA and published in conjunction with LabX.
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