The analysis of organic constituents in leaves by pyrolysis-gas chromatography and its application to selected environmental effects on plants

Abstract

Forest decline has caused great concern in North America. In recent years, the relationship between environmental stress and the concentration of certain organic compounds in plant leaves, e.g., carbohydrates, phenolics and tannins, has been recognized. Traditional methods for the determination of organic constituents in leaves are very difficult as well as time-consuming. As an alternative method of analysis, Pyrolysis-Gas Chromatography-Mass Spectrometry (PY-GC-MS) can be a rapid and comprehensive method to profile the chemical composition of biomaterials. Furthermore, enhanced structural information of biomolecules containing acidic functional groups has been obtained by a modification of direct pyrolysis - simultaneous pyrolysis methylation (SPM). Initial investigations were focused on the characterization of important classes of biomarkers (e.g., tannins, phenolics) in leaves, and, optimization of sample preparation procedures and pyrolysis conditions. Finally, the pyrolytic techniques were examined as a tool to quantify the compositional changes in leaves of trees which have been subjected to different environment stresses. Results will be reported for three field applications 1) the effect of thinning on balsam fir trees 2) the effect of fertilization on kalmia plant 3) and the effect of ozone on white pine trees. It was found that certain pyrolysates of carbohydrates, tannins and of a dihydrochalcone where good indicators of fertilization and water stress. Two unique pyrolysate bio-markers were discovered in white pine needles as indicators of ozone fumigation levels and ozone damage.