Development and validation of a reliable LC-MS/MS method for quantitative analysis of usnic acid in Cladonia uncialis

Objective The purpose of this study was to develop and validate a specific and sensitive liquid chromatography tandem mass-spectrometry method for quantification of usnic acid concentration in the lichen, Cladonia uncialis, suitable for detection of relatively small fluctuations of usnic acid concentration in response to environmental changes. Results The resulting method was fully validated according to international guidelines and demonstrated good selectivity and sensitivity with minor levels of a matrix effect and high accuracy.