Derivatization Solid-Phase Microextraction Gas Chromatographic-Mass Spectrometric Determination of Organic Acids in Tobacco

摘要

Isovaleric, valeric, hexanoic, benzole, phenylacetic, 3-methylvaleric, heptanoic, octanoic, and nonanoic acids are converted to their methyl esters and quantitated for flue-cured tobacco grades of increasing stalk position using derivatization headspace solid-phase microextraction (SPME) with selected ion monitoring mode mass spectrometry. Qualitative analysis of the headspace of tobacco derivatized with methanolic hydrochloric acid using a 65-μm Carbowax-divinylbenzene SPME fiber indicates selectivity for relatively nonpolar volatile and semivolatile organic acid methyl esters. By contrast, direct exposure of an 85-μm polyacrylate SPME fiber to derivatives followed by GG-MS analysis provides the capability to evaluate significantly more polar organic acid methyl esters such as malic acid dimethylester and citric acid trimethylester.