Characterization of Electron Ionization Mass Spectral (EIMS) Fragmentation Patterns of Chloropropanol Esters of Palmitic Acid Using Isotope Labeling Technique
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Bibliographic record
Abstract
Chloropropanol (CP) esters are a class of thermally-induced toxicants that are mainly formed in refined edible oils. The structural diversity of these esters presents significant analytical challenges which have often been overcome through analysis of their corresponding free alcohols after a hydrolysis step. Mass spectrometry-based methodologies incorporating characteristic fragmentation patterns of particular isomers of CP esters greatly facilitates their identification. The electron ionization mass spectra (EIMS) of various isomers of synthetic and commercially available (13)C- and (2)H-labeled CP ester standards of palmitic (C16) and other short chain fatty acids (C3 to C10) were generated and analyzed using GC/MS. Short chain CP esters were synthesized by reacting their respective acid anhydrides with the corresponding 3-chloro- and 2-chloro- propanediols in addition to 1,3-dichloro- and 1,2-dichloropropanols. Five fragmentation pathways were identified. Four of the five pathways, such as α-cleavage, McLafferty rearrangement, α-H rearrangement and cyclic acyloxonium ion formation, were characteristic of CP mono- and diesters. The remaining pathway generating chloronium ion was found only in dichlorinated isomers. The proposed fragmentation pathways for the palmitic acid esters were confirmed through the use of (13)C- and (2)H-labeled CP ester standards of palmitic acid, and the generality of identified fragmentation patterns was confirmed through the identification of equivalent ions in the mass spectra of short chain fatty acids (C3 to C16). Characteristic ions that were identified in this study retaining the chlorine atom in their structures can be considered as potential markers for the presence of CP esters.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it