ANALYSIS OF SOLANUM ALKALOIDS USING INTERNAL STANDARDIZATION AND CAPILLARY GAS-CHROMATOGRAPHY

A capillary gas chromatographic method has been developed for quantitation of the principal steroidal alkaloids of Solanum chacoense and Solanum tuberosum. The method uses tomatine as an internal standard and requires less than 100 mg of dry weight of plant tissue. Internal standard recoveries were approximately 80-95%. Glycoalkaloids were concurrently extracted and hydrolyzed using 1 N HCI in methanol. The underivatized aglycons, solanidine, leptinidine, tomatidine, and acetylleptinidine, the peak areas of which constituted between 70 and 80% of the total peak area of the chromatogram, were resolved in less than 20 min using a nonpolar (Rt(x)-1) megabore fused silica column, with retention times of l0.34, 14.47, 15.44, and 15.96 min,respectively. Retention times varied less than 0.2%. The procedure was applied to the quantitation of steroidal alkaloids from S. chacoense and S. tuberosum leaves and tubers, for which relative standard errors were typically less than 2% of the mean.