Determination of solanidine- and tomatidine-type glycoalkaloid aglycons bygas chromatography/mass spectrometry

A combined derivatization method for gas chromatographic/mass spectrometric (GC/MS) analysis of steroidal glycoalkaloid (SGA) aglycons was developed u sing both trimethylsilylation and pentafluoropropionylation. In comparison with underivatized or only silylated aglycons, the new technique produces m ore specific and abundant fragmentation for compounds with a tomatidine-typ e structure. For example, the difference between solasodine and tomatidine, the former containing a double bond at position 5,6 in the steroidal skele ton, can be observed by their base peak fragments at m/z 417 (C24H41O2Si2) and m/z 419 (C24H43O2Si2). The method is well suited for the simultaneous d etermination of both solanidane- and spirosolane-type SGA aglycons from Sol anum species and hybrids. The reproducibility of the method, including SGA extraction, hydrolysis, derivatization, and quantitative GC/MS analysis, wa s <6% (CV) for the principal aglycons determined from a hybrid between a wi ld potato species, Solanum brevidens Phil., and a cultivated potato, S. tub erosum L. A single ion monitoring technique using specific fragments m/z 41 9 and 417 could be applied for the determination of minor stereoisomers, wh ich are often overlapped by large amounts of tomatidine.