Applications of capillary electrophoresis - mass spectrometry interfaced by a flow-thourgh microvial electrospray ionization sprayer
Bibliographic record
Abstract
Capillary electrophoresis – electrospray ionization – mass spectrometry (CE-ESI-MS) combines the superior separation capability of CE and detection and characterization ability of MS. Different CE separation modes can be coupled to ESI-MS, employing an interface with a flow-through microvial. In the first part of the thesis, recent development of CE and CE-MS applications in the analysis of complex samples are reviewed. Capillary isoelectric focusing (cIEF) is an important tool for the separation and characterization of amphoteric molecules based on isoelectric points. Minute structural changes on a large protein can result in changes in isoelectric point, and the changes can be detected by slab gel isoelectric focusing or capillary isoelectric focusing. A systematic study on the interactions among carrier ampholytes, sample media and capillary inner coatings was carried out to provide guidelines for choosing feasible combinations that can achieve isoelectric focusing and successful chemical mobilizations. Within the 0.1%-1% (w/v) carrier ampholytes concentration range, small forward EOFs will ensure a higher chance of good focusing and successful electrophoretic mobilization, while a negative EOF will hinder these processes. Feasible combinations of experimental conditions are summarized. Using the optimized conditions, we reported the direct observation of the shape of focused ampholyte bands in the cIEF process by online cIEF- ESI-MS. The ampholyte bands directly detected by MS have the potential to enable a more accurate pI determination for unknown amphoteric molecules. Immunoglobulin G from rabbit serum is used to demonstrate this possibility. In Chapter 6, a CE-MS method was developed to monitor the concentration variations of major nutrients and/or metabolites in human embryonic stem cell CA1S culture medium over a culturing cycle. Concentration changes for nutrients and/or metabolites in the culturing media provided information on the cell growth behavior without destructing living cells. In the last part of the thesis, an atmospheric ion lens was applied to the flow-through microvial CE-ESI-MS interface to improve the electrospray ionization and sampling efficiency. A mixture of amino acids was tested to show the increased signal-to-noise ratios. The atmospheric ion lens also gives more flexibility when choosing the EOF and chemical modifier flow rates.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".