FAST, SAFE, AND RELIABLE METHODS FOR EXTRACTION OF MAJOR INORGANIC CATIONS FROM SMALL QUANTITIES OF WOODY PLANT-TISSUES

Two simple and fast methods for the extraction of major inorganic cati ons (Ca, Mg, Mn, K) from small quantities of stemwood and needles of w oody plants were developed. A 3.2- or 6.4-mm cobalt drill bit was used to shave samples from disks and increment cores of stemwood. For ion extraction. wood (ground or shavings) or needles were either homogenzi ed using a Tekmar Tissumizer or frozen and thawed (three times) in 0.0 1 M HCl. After filtration through a 0.45-mum nylon filter, the extract was analyzed for ion content using direct current plasma atomic emiss ion spectrometry. Quality control samples of pine needles obtained fro m the National Institute of Standards and Technology, and individually pooled wood samples of red spruce (Picea rubens Sarg.) and red oak (Q uercus rubra L.). were used to compare these two methods of extraction with the most commonly used method of wet ash digestion. The results of either method of extraction (freezing thawing or homogenization) we re higher than or similar to those obtained by wet digestion. Direct u se of drill shavings eliminates the need for making wood chips by hand and grinding in a Wiley mill. Moreover, both approaches are relativel y safe, since they do not require the use of hot concentrated acids an d strong oxidizing agents. These methods may be particularly useful fo r the analysis of major inorganic cations from extremely small size sa mples (25 mg) such as individual annual growth rings of mature trees.