Behaviour of soyasapogenol B under optimised hydrolysis and ESI mass spec conditions

Soyasaponins are oleanane triterpenoids found in soy (Glycine max Merr). The analysis of the main aglycone (soyasapogenol B) is hampered by inconsistent ion fragmentation patterns produced during MS analysis. The greatest (p < 0.05) increase in soyasapogenol B during acid hydrolysis HCl (5% (v/v)) was at 100 °C (84.59 ± 4.73 μg/ml), followed by 120 °C (69.82 ± 6.20 μg/ml) and 80 °C (46.54 ± 6.41 μg/ml). The capillary temperature (LC–ESI-MS) of 220 °C produced the greatest (p < 0.05) intensity of soyasapogenol B ion. Temperatures between 200 and 250 °C consisted the optimum temperature range for analysing soyasapogenol B. At low capillary temperatures (<200 °C), the soyasapogenol B ion ([M−H]− = 457.4) was converted to an ion m/z at 441, while, at temperatures ⩾250 °C the soyasapogenol B ion produced ions m/z at 440 and 437. We report an analysis procedure for detecting intact soyasapogenol B molecular ion without the typical fragmentation reported in the literature.