Reverse Spectral Search Reimagined: A Simple but Overlooked Solution for Chimeric Spectral Annotation
Bibliographic record
Abstract
The exponential growth of untargeted metabolomics data, now reaching billions of mass spectra in public repositories, benefits from reannotation strategies for data reuse. While tandem mass spectrometry (MS/MS) library matching remains the gold standard, annotation workflows face a critical bottleneck: chimeric spectra. These composite spectra, arising from simultaneous fragmentation of multiple precursor ions, compromise the ability to annotate MS/MS spectra against nonchimeric reference spectra. Here, we demonstrate that an enhanced version of reverse spectral search, a principle first introduced in 1975 but largely overlooked, provides a simple, computationally efficient solution, rescuing up to 62% more metabolite annotations in benchmark data sets while maintaining stringent quality control. The enhanced reverse spectral search is now added to the GNPS ecosystem. Source codes can be accessed at https://github.com/Philipbear/reverse_search.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.007 | 0.020 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.004 | 0.006 |
| Open science | 0.004 | 0.008 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.010 | 0.010 |
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".