Observed Mass (m/z)^a

ID

Electron Paring

Nitrogen Rule

No. of Nitrogen(s)

Proposed Formula

Theoretical Mass^b (m/z)

557.2

Parent

[M-H]⁻

EN

2

${\text{C}}_{\text{33}}{\text{H}}_{\text{34}}{\text{FN}}_{\text{2}}{\text{O}}_5^{-}$

557.2

479.3

F1

EE

EN

2

${\text{C}}_{31}{\text{H}}_{28}{\text{FN}}_{\text{2}}{\text{O}}_2^{-}$

479.2

453.2

F2

EE

EN

2

${\text{C}}_{29}{\text{H}}_{26}{\text{FN}}_{\text{2}}{\text{O}}_2^{-}$

453.2

397.2

F3

EE

EN

2

C₂₆H₂₂FN₂O⁻

397.2

278.1

F4

EE

ON

1

C₁₉H₁₇FN⁻

278.1