Foliar storage and extraction methods for quantitative analysis of piperidine alkaloids from ponderosa pine (Pinus ponderosa)

Abstract

Yields of 2,6-disubstituted piperidine alkaloids from ponderosa pine (Pinus ponderosa) foliage were compared for frozen, air- and oven-dried samples stored for 3 days and for 5 weeks. Oven-drying provided the most stable alkaloid yields, but biological variation was greater than the variation between the storage methods. Alkaloid yields were also compared for the classical liquid–liquid partitioning method and a solid-phase partitioning (SPP) method using Extrelut™ columns. Under proper conditions, both methods were reasonably accurate, but biological variation in alkaloid content was much greater than experimental variation from either extraction method. In order to optimize the SPP method, it was necessary to use chloroform rather than dichloromethane as the eluting solvent, and to rinse the column more than the manufacturer directs. The SPP method requires less solvent and time per sample, thus it may be preferable for ecological studies where numerous samples are required to detect differences against high background variation. Zinc dust treatment, to reduce possible alkaloid N-oxides in SPP extracts, failed to increase yields, suggesting the absence of such compounds. Copyright © 1999 John Wiley & Sons, Ltd.