A high throughput analysis of boronic acids using ultra high performance liquid chromatography-electrospray ionization mass spectrometry

Abstract

An ultra high performance liquid chromatography electrospray ionization mass spectrometry method was developed for the analysis of a broad range of boronic acids present in industrial samples. A set of 7 boronic acids having different functional groups was successfully separated on an Acquity BEH C18 column using 10 mM ammonium acetate and acetonitrile as the mobile phase. The proposed method has excellent potential for high-throughput analysis as it enjoys the advantage of one minute run time without using any sample pretreatment or pre-derivatization which has been mandatorily followed during boronic acid analysis to avoid dehydration. The influence of specific instrument parameters of UPLC-MS was examined and an optimized condition has been proposed for the identification of boronic acids and to reduce the predominant formation of boroxine, solvent adduct and dimer ions which normally complicate the analysis of boronic acids. The proposed method was further validated by analyzing a wide range of 20 boronic acids having different functional groups. The estimated recovery values of the boronic acids were ranged from 97.1 to 105.7%, and precision, expressed as relative standard deviation, was below 2.0% and the linearity R² was 0.98 based on UV response. This method provides LOD of 0.1 μg and LOQ of 1.0 μg for the majority of boronic acids and was successfully applied for the quantitative analysis of boronic acids in industrial applications such as reaction monitoring samples from Suzuki coupling, arylation of amines and phenols.