Design and performance of an electrospray ionization time-of-flight mass spectrometer
Bibliographic record
Abstract
In order to circumvent the limitations of a quadrupole mass filter, which so far has been the most common mass analyzer for use with electrospray ionization, a mass spectrometer coupling electrospray with time-of-flight mass analysis has been constructed. The design of this spectrometer, including a simple electrospray ion source, an atmosphere–vacuum interface without a rf-only quadrupole/multipole that discriminates against low mass ions which can be used for internal calibration, orthogonal extraction, and a reflectron, is presented together with its performance characteristics. A resolving power of 7500 was obtained for the +5 ion of bovine insulin and the detection limit for the same molecule was shown to be 1 f mol. Mass accuracy using a conventional two-point calibration is 60 ppm for internal calibration on low mass ions and better than 100 ppm for external calibration on peptide ions. An improved mass accuracy equal to 10 ppm was achieved using internal three-point calibration on low mass ions naturally present in the spectra. The dynamic range of a single sample was found to be at least 400:1.
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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 | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.003 |
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".