ABSTRACT

We studied the alpha-cellulose extraction procedure used for the tropical tree sungkai (Peronema canescens Jack) using an improved Teflon extraction vessel to achieve reliable oxygen isotopic analysis for paleoclimate reconstruction in tropical Asia. We assessed the change in the attenuated total reflection infrared (ATR-IR) spectra and oxygen isotopic ratios during the extraction. Results suggest that the optimum extraction time durations using thin sungkai samples (≤15 mg, 20-μm thickness shaved wood samples) are (i) 30 min for resin removal from tree contents in an organic solvent extraction, (ii) 6 h (1 h × six times) for delignification in a bleaching reaction, and (iii) 2 h 15 min (45 min × three times) for lignin and hemicellulose removal in an alkali reaction. Moreover, our result suggests the necessity of removing impurities such as lignin completely because the oxygen isotopic ratio of lignin in this sample was found to be significantly lower than that of alpha-cellulose.