Selection of Buffers in Lc - Ms / Ms : an Overview

Liquid chromatography-mass spectrometry (LC-MS, or alternatively HPLC-MS) is an analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry. LCMS is frequently used in drug development at many different stages including Peptide Mapping, Glycoprotein Mapping, Natural Products Dereplication, Bioaffinity Screening, In Vivo Drug Screening, Metabolic Stability Screening, Metabolite Identification as well as Impurity Identification. Selecting the proper buffer pH is necessary to reproducible separate ionisable compounds by reverse phase liquid chromatography or LC-MS. Selecting an improper pH for ionizable analytes often leads to asymmetric peaks that are broad, tail, split or shoulder. Sharp and symmetrical peaks are necessary in quantitative analysis in order to achieve low detection limits, relative standard deviations (RSD) between injection, and reproducible retention times. In the present article, we have concentrated on the aspect when and why buffering is needed in LC-MS, how to choose buffer pH as well as criteria for selecting buffers for ion pair reagents. A properly buffered mobile phase is very important in a successful reverse phase method for optimal peak shape, detection limit, and consistent resistant times. The selection of proper buffer purely depends on analyte’s functional group and pKa Values.