Gas chromatographic method for determining strychnine residues in alfalfa

A gas-liquid chromatographic procedure is described for determining strychnine in alfalfa with a nitrogen-phosphorus detector. Alfalfa samples containing strychnine residues are chopped and extracted in a blender using ethyl acetate, sodium carbonate, and sodium sulfate, and the organic extract is extracted with 0.1N H2SO4 solution, made basic, and subsequently extracted with methylene chloride. Following concentration, the strychnine residues are quantitated by peak height, using an external standard. Recoveries for 0.05 ppm spikes were 88 +/- 11%.