NMR Quantitation of Natural Products at the Nanomole Scale

We describe a simple and accurate method for quantitation by solvent C-13-satellites (QSCS) of very small amounts of natural products using microprobe NMR spectroscopy. The method takes advantage of integration of C-13 satellite peaks of deuterated solvents, in particular CDCl3, that have favorable intensities for measurements of samples in NMR microcoils and microprobe tubes in the 1-200 nanomole range.