The fragment ion
of metronidazole is 128.0 m/z and 81.9 m/z, the fragment ion
of tinidazole is 128.0 m/z and 92.8 m/z, the fragment ion
of ornidazole is 127.9 m/z and 81.9 m/z, the fragment ion
of ofloxacin is 261.0 m/z and 221.0 m/z, the fragment ion
of metronidazole is 314.0 m/z and 231 m/z, and the fragment ion
of metronidazole is 245.0 m/z and 203 m/z.
The presence of a minor fragment ion
at m/z 120 further indicated the existence of cysteine.
HRMS provides accurate mass measurement, narrowing the possible elemental composition for each fragment ion
and increasing the reliability and efficiency of data processing (23-27).
The fragment ion
at m/z 583 [[M-H].sup.-] was a molecular ion.
The MS/MS spectrum shows the most abundant fragment ion
at m/z 353, indicating the loss of rhamnose moiety.
Peaks 10 and 11 exhibited the same [[M-H].sup.-] ions at m/z 593 and fragment ion
at m/z 285 [[[Y.sub.0]].sup.-], indicating that they are isomers.
Meanwhile, their M[S.sup.2] spectrums showed a similar fragment ion
at m/z 191 as base peak.
A fragment ion
at m/z 306 refers to the deprotonated glutathione (GSH) moiety and CNLs of 120 and 146, indicating the presence of a rhamnoside group.
Herein, we developed an alternative method to determine protein KAc stoichiometries globally based on isotope labeling with the detection and quantification of a small diagnostic fragment ion
for KAc found in tandem mass spectrometry (MS/MS) spectra.
The complex A showed base peak at m/z = 152 due to [C.sub.10][H.sub.17]N fragment ion
and 4,4'-dimethoxy-2,2'-bipyridine ligand in the complex showed peak at m/z = 217 with relative intensity of 25%.
The ESI-MS/MS spectra showed [[M-H] .sup.-] at m/z 515.5, fragment ion
[[M-[C.sub.9][H.sub.6][O.sub.3]].sup.-] at m/z 354.1, and fragment ion
[MH- 2C9H6O3]- at m/z 191.2 (Figures 2(c), 2(d), 2(e), and 2(f)).
Protein mass: 321.5 Da Fragment ion
calculator results Sequence: N-Ala-Phe-Cys-C Fragment ion
table, monoisotopic masses Seq No.