Structural determination of the novel fragmentation routes of zwitteronic morphine opiate antagonists naloxonazine and naloxone hydrochlorides using electrospray ionization tandem mass spectrometry
Bibliographic record
Abstract
Electrospray ionization quadrupole time-of-flight (ESI-QqToF) mass spectra of the zwitteronic salts naloxonazine dihydrochloride 1 and naloxone hydrochloride 2, a common series of morphine opiate receptor antagonists, were recorded using different declustering potentials. The singly charged ion [M+H-2HCl](+) at m/z 651.3170 and the doubly charged ion [M+2H-2HCl](2+) at m/z 326.1700 were noted for naloxonazine dihydrochloride 1; and the singly charged ion [M+H-HCl](+) at m/z 328.1541 was observed for naloxone hydrochloride 2. Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) experiments established the fragmentation routes of these compounds. In addition to the characteristic diagnostic product ions obtained, we noticed the formation of a series of radical product ions for the zwitteronic compounds 1 and 2, and also the formation of a distonic ion product formed from the singly charged ion [M+H-HCl](+) of naloxone hydrochloride 2. Confirmation of the various established fragmentation routes was effected by conducting a series of ESI-CID-QqTof-MS/MS product ion scans, which were initiated by CID in the atmospheric pressure/vacuum interface using a higher declustering potential. Deuterium labeling was also performed on the zwitteronic salts 1 and 2, in which the hydrogen atoms of the OH and NH groups were exchanged with deuterium atoms. Low-energy CID-QqTof-MS/MS product ion scans of the singly charged and doubly charged deuteriated molecules confirmed the initial fragmentation patterns proposed for the protonated molecules. Precursor ion scan analyses were also performed with a conventional quadrupole-hexapole-quadrupole tandem mass spectrometer and allowed the confirmation of the genesis of some diagnostic ions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".