Table 1.
The main ions of triterpenoid standards in direct infusion μAPPI-MS with toluene and acetone dopants. The most abundant ions are presented for each compound (intensity over 20% of the main peak). The sample concentrations were 10 μM, and sample solution flow rate was 10 μL min−1. The data was collected in both positive and negative ion modes
| Toluene | Acetone | |||
|---|---|---|---|---|
| Triterpenoid | (+) mode | (−) mode | (+) mode | (−) mode |
| Betulin | 442 M+• | 441 [M-H]− | 425 [M + H-H2O]+ | – |
| Lupeol | 426 M+• | – | 409 [M + H-H2O]+ | – |
| Betulinic acid | 456 M+• | 455 [M-H]− | 439 [M + H-H2O]+ | 455 [M-H]− |
| Betulonic acida | 454 M+•, 455 [M + H]+ | 453 [M-H]− | 455 [M + H]+, 437 [M + H-H2O]+ | 453 [M-H]− |
| Allobetulina | 442 M+•, 443 [M + H]+ | – | 443 [M + H]+, 425 [M + H-H2O]+ | – |
| Allobetulone | 441 [M + H]+ | – | 441 [M + H]+ | – |
aWhen toluene was used as the dopant, the molecular ion (M+.) and protonated molecule ([M + H]+) were observed as main ions at intensity of approx. 1:1