What are the commonly used buffers in HPLC?
The retention time of ionizable compounds is very sensitive to the pH of the mobile phase, so it is necessary to control the pH of the mobile phase by adding a buffer. Buffers can maintain a stable pH when a small amount of acid or base is added. Many substances have been used as buffers in HPLC. The most commonly used buffers for HPLC with UV detection are phosphates and acetates. Phosphates and acetates are particularly useful buffers because they can be used at wavelengths below 220 nm. When a mass spectrometer is used as an LC detector (LC-MS), the mobile phase must be volatile because one of the functions of the LC-MS is to vaporize the mobile phase. This means that the most popular LC-UV phosphate buffer cannot be used. The most common HPLC buffers used for LC-MS are acetate, TFA (0.1%), formic acid, ammonium formate, and ammonium bicarbonate.
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