Comparison of three buffer solutions for amino acid derivatization and following analysis by liquid chromatography electrospray mass spectrometry

For reversed phase separation amino acids are usually derivatized. Several derivatization reactions are carried out at basic pH. In the present work, influence of three basic buffer solutions on liquid chromatography electrospray ionization mass-spectrometric (LC–ESI-MS) analysis of amino acid derivatives was studied. Borate buffer – the most common derivatization buffer – was found to influence ESI ionization up to 23 min retention time. For 9-fluorenylmethylmethoxycarbonyl chloride (Fmoc-Cl derivatization) carbonate buffer should be preferred as it provides higher responses. Hexafluoroisopropanol (HFIP) buffer improves chromatographic peak shapes and responses for diethyl ethoxymethylenemalonate (DEEMM) derivatives.

► Buffer used for amino acid derivatization has serious impact on LC–ESI-MS analysis.
► Carbonate buffer provides higher responses for Fmoc-Cl derivatives.
► HFIP buffer improves detectability of DEEMM derivatives.