Analytical study of free and ester bound benzoic and cinnamic acids of gum benzoin resins by GC-MS and HPLC-frit FAB-MS

Sumatra benzoin resins originating from two species of Styrax were studied using modern analytical techniques. Analysis of these types of resins usually involves several steps including alkaline hydrolysis, derivatization of the polar groups and chromatography. Two different resins, and three different qualities from each resin, were investigated using a fast analytical method which omits the hydrolysis step and makes it possible to identify all of the individual components of the resin in one gas-chromatography-mass spectrometry measurement. Resins from both Styrax benzoin Dryand and S. paralleloneurum Perk contain free cinnamic and benzoic acids and their corresponding esters with p-coumaryl and coniferyl alcohols, although in different relative amounts. Pinoresinol and some higher molecular weight esters of cinnamic and benzoic acids were also found. The structure of these compounds was verified by high performance liquid chromatography-continuous flow fast atom bombardment mass spectrometry. For quantitation, gas chromatography with flame ionization detection was performed. Molecular response factors of the identified compounds were calculated as correction factors of the peak areas.