Flavonoids are secondary plant metabolites of great structural variety and high medicinal significance. The search for new chemical entities and the quality control of flavonoid containing natural products require easy-to-use but reliable and robust analytical methodologies. For structural elucidation of flavonoids and their glycosides, nuclear magnetic resonance (NMR) and mass spectroscopy (MS) are the generally used techniques. In phytochemical analyses, however, high amounts of flavonoids are difficult to isolate for NMR, thus low sample volume requiring MS based methods are emerging. This review summarizes and compares currently available methods for structural elucidation of flavonoids by LC-MS and LC-MS(n), and focuses on the identification options of unknown flavonoid glycosides in complex samples (e.g., plant extracts) with the emphasis on the differentiation of isomeric compounds.

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Picomole amounts of oligodeoxynucleotides [polydeoxyadenylic acids, (dA)4&..s] were baseline resolved and analyzed in <8 min by high-performance capillary electrophoresis with polyacrylamide gels. In addition, fast analysis of a crude 70-mer oligodeoxynucleotide and a slab gel-purified 99-mer oligodeoxynucleotide was accomplished, demonstrating the ability of high-performance capillary electrophoresis to characterize rapidly synthesized oligonucleotides. Besides analytical separations, 800 ng of a primer (20-mer) was isolated in <20 min. The purified species was collected in water and subsequently used as a probe in a standard dot-blot analysis. The use of high-performance capillary electrophoresis for the analysis and purification of a variety of biopolymers is simple, rapid, and has the potential for automation. (7), was used at a wavelength of 260 nm. The tubing and the detector were cooled with a thermostated air bath. The power supply outlets were connected to platinum electrodes, 5, immersed in buffer reservoirs, 6 (for analytical runs), or in a microcentrifuge vial, 7 (for collection). An analog/digital interface, 8 (Nelson, Cupertino, CA), attached to a recorder, 9, and IBM PC/XT, 10, were used to record the results and process the data.Materials. The oligodeoxynucleotide (5' GCCACGTCCA-GATTTATCAG 3') in Fig. 4 was synthesized on a model 380A DNA synthesizer (Applied Biosystems, Foster City, CA) using the silica-based solid-phase method (8) and the proton-activated nucleoside phosphoramidate method with methoxyphosphoramidates (9). The side-chain protecting groups were liberated by treatment with ammonium hydroxide at 550C for 6 hr. After this step, the oligodeoxynucleotide was recovered by lyophilization and dissolved in water.Polydeoxyadenylic acid mixture (dA)40-60 was purchased from Pharmacia. The crude 70-mer and slab gel-purified 99-mer oligodeoxynucleotides were the gift of N. Bischoffer (Genentech, South San Francisco, CA Procedure. A modified version (10) of the polyacrylamide gel capillary column described in ref. 5 was filled with polyacrylamide gel (T = 7.5%, C = 3.3%) (11) in 7 M urea/0.1 mM Tris/0.25 mM borate, pH 8.3. The field applied to the gel was 400 V/cm. To remove impurities from the acrylamide gel, the capillary gel column was preelectrolyzed at 6 kV for 30-60 min. During electrophoresis, the capillary was maintained at room temperature. The samples were electrophoretically injected into the column by dipping the cathodic end of the capillary into an aqueous solution of the sample and applying a field of 400 V/cm for =10 sec.Abbreviations: HPCE, high-performance capillary electrophoresis. ITo whom reprint requests should be addressed. 9660The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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