Rapid Multiresidue Screen for Alkaloids in Plant Material and Biological Samples

Abstract

A multiresidue screen for the quantitative and qualitative determination of alkaloids in plant material, animal ingesta, tissue, and biological fluid is described. The alkaloids were extracted with 5% ethanol in ethyl acetate (v/v) after the addition of aqueous NaOH. The organic extract was cleaned up by partitioning with 0.5 N HCl. The aqueous phase was made alkaline; the alkaloids were retained on a polymeric C-18 minicolumn and subsequently eluted with ethyl acetate. The concentrated extract was analyzed quantitatively by GC/NPD. The alkaloids coniine, nicotine, atropine, retrorsine, solanidine, and strychnine were tested to measure the performance of the method. Fortifications at 10 and 1 μg/g of the six model alkaloids in alfalfa hay, bovine rumen content, liver, urine, and serum were prepared. The method recovered the six alkaloids in the range of 113-82% at the 10 μg/g level and 113-72% at the 1 μg/g level. Qualitative screening methods using a modified commercial TLC system and GC/MS were developed. Theoretical detection limits for qualitative screening ranged from 0.2 to 1.0 μg/g, while theoretical detection limits for GC/NPD ranged from 0.025 to 0.2 μg/g for the compounds studied using a nominal 5 g sample. The method was used successfully in a diagnostic case to identify lupine alkaloids in rumen contents