A study of the ozonolysis of model lipids by electrospray ionization mass spectrometry
Bibliographic record
Abstract
RATIONALE: The ozonolysis of vegetable oils has been proposed as step to functionalise unsaturated lipids for the production of bio-based chemicals and materials. The observation of ozonolysis products by mass spectrometry will facilitate mechanistic studies that are essential for the further development of industrial processes based on lipid ozonolysis. METHODS: Ozonolysis of the model lipids methyl oleate and triolein was performed and samples were taken over a range of reaction times. Ozonlysis products were separated by normal and non-aqueous reversed-phase (NARP) liquid chromatography (LC) coupled to electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) using a hybrid quadrupole-time of flight instrument. Post-column addition of ammonium acetate solutions aided ionization. Volatile reaction products were observed using gas chromatography/electron impact mass spectrometry (GC/MS). RESULTS: Secondary ozonides, reaction intermediates and previously unreported high molecular weight product dimers were observed as intact molecular ammonium ion adducts under positive ESI. The main fragment ions obtained by MS/MS were from cleavage of the trioxolane group, loss of fatty acyl chain and fragmentation between n-8 and n-9 on the fatty acyl chain. The MS/MS spectra and exact mass measurements explain most of the ozonolysis reaction products. CONCLUSIONS: LC/MS, LC/MS/MS and GC/MS results demonstrate that the products from the ozonolysis of the model lipids methyl oleate and triolein are consistent with known ozonolysis reaction pathways. LC/MS techniques using non-aqueous chromatography have permitted the direct observation of mono-, di- and tri-1,2,4-triloxanes which are the secondary ozonides formed by the ozonolysis of triolein. It was also shown that intermediates formed during the ozonolysis of triolein can combine to form high molecular weight ozonide dimers.
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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) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".