Comparative Analysis of Cellulose Preparation Techniques for Use with 13C, 14C, and 18O Isotopic Measurements

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• 作者：Julia B. Gaudinski ; Todd E. Dawson ; Sylvie Quideau ; Edward A. G. Schuur ; John S. Roden ; Susan E. Trumbore ; Darren R. Sandquist ; Se-Woung Oh ; and Roderick E. Wasylishen
• 刊名：Analytical Chemistry
• 出版年：2005
• 出版时间：November 15, 2005
• 年：2005
• 卷：77
• 期：22
• 页码：7212 - 7224
• 全文大小：355K
• 年卷期：v.77,no.22(November 15, 2005)
• ISSN：1520-6882

文摘

A number of operationally defined methods exist forpretreating plant tissues in order to measure C, N, and Oisotopes. Because these isotope measurements are usedto infer information about environmental conditions thatexisted at the time of tissue growth, it is important thatthese pretreatments remove compounds that may haveexchanged isotopes or have been synthesized after theoriginal formation of these tissues. In stable isotopestudies, many pretreatment methods focus on isolating"cellulose" from the bulk tissue sample because cellulosedoes not exchange C and O isotopes after original synthesis. We investigated the efficacy of three commonlyapplied pretreatment methods, the Brendel method andtwo variants of the Brendel method, the Jayme-Wisemethod and successive acid/base/acid washes, for useon three tissue types (wood, leaves, roots). We thencompared the effect of each method on C and O isotopecomposition (¹³C, ¹⁴C, ¹⁸O), C and N content, and chemical composition of the residue produced (using ¹³Cnuclear magnetic resonance (NMR)). Our results raisedconcerns over use of the Brendel method as published,as it both added C and N to the sample and left a residuethat contains remnant lipids and waxes. Furthermore, thismethod resulted in ¹⁸O values that are enriched relativeto the other methods. Modifying the Brendel method byadding a NaOH step (wash) solved many of these problems. We also found that processed residues vary bytissue type. For wood and root tissues, the ¹³C NMRspectra and the ¹⁸O and ¹³C data showed only smalldifferences between residues for the Jayme-Wise andmodified Brendel methods. However, for leaf tissue, ¹³CNMR data showed that Jayme-Wise pretreatments produced residues that are more chemically similar tocellulose than the other methods. The acid/base/acidwashing method generated ¹³C NMR spectra with incomplete removal of lignin for all tissues tested and bothisotopic, and ¹³C NMR results confirmed that this methodshould not be used if purified cellulose is desired.