Figure 3.

Structures of SS427 and cort21S and identity of SS425 and cort21S by mass spectrometry. A, Structure of SS427. B, Structure of corticosterone 21-sulfate. C–F, Mass spectrometry of cort21S and SS425 reveals identical fragmentation patterns with two different instruments. C, D, A triple quadrupole instrument was used, and identical fragments were observed for SS425 (C) and cort21S (D). E, F, An ion trap instrument was used, and identical fragments were observed for SS425 (E) and cort21S (F).