GC/MS analysis for strophanthidin and digitoxigenin in "Moroheiya" (Corchorus olitorius L.)

It has been known that the seed of "Moroheiya" (Corchorus olitorius L.) con tains cardiac glycosides such as Strophanthidin (SP) as an aglycon. Using t rimethylsilyl (TMS) derivatization and GC/MS analysis, a simultaneous metho d for the determination of SP and Digitoxigenin (DG) in "Moroheiya" was dev eloped. The condition for TMS derivatization of SP and DG was examined usin g commercially available standard reagents. Each reagent was treated with a mixture of pyridine, N,O-bis (trimethylsilyl)-acetamide, trimelhylsiiylimi dazole and trimethylchlorosilane and analyzed by GC/MS. Their mass spectra demonstrated the formation of the completely and partially derivatized TMS ethers, SP (TMS)(4), SP (TMS)(3), SP (TMS)(2), DG (TMS)(3) and DG (TMS)2. T he complete derivatization from SP to SP (TMS)(4) and DG to DG (TMS)(3) req uired the reaction for about 20 h at 100 degrees C. SP and DG in C. olitori us seeds and processed "Moroheiya" foods were prepared as follows, "Morohei ya" sample was hydrolyzed in a 1% sulfuric acid-methanol (1:1, v/v), and th en the resulting hydrolyzate was extracted with dichloromethane. The extrac t was dried up and derivatized for 20 h at 100 degrees C. The resulting der ivatives, SP (TMS)(4) and DG (TMS)3 were determined by GC/SIM (selected ion monitoring). The mass spectra of those derivatives were not significantly affected by interfering components. Thus, this method is confirmed to be ve ry useful for qualitative and quantitative analysis of SP and DG in "Morohe iya" samples. The detection limits of SP and DG were 5 mg/kg and 1 mg/kg, r espectively. By the present method, 5.9-6.2 g/kg of SP and 0.15-0.24 g/kg o f DG were detected in C. olitorius seeds, while neither SP nor DG was detec ted in processed "Moroheiya" foods.