Electrospray ionisation: difference between revisions
Diff·revision 2 → 3·04:55, 18 Sep 2024
Difference between revision 2 and revision 3 of Electrospray ionisation. 5 lines changed; the page grew by 653 bytes.
| Revision 2 — 17:12, 5 Sep 2024 Chromatokid (talk) add the note on co-elution and what it hides 1,326 bytes ±0 | Revision 3 — 04:55, 18 Sep 2024 ColumnOvenCoy (talk) add the system-suitability criteria the method actually specifies 1,979 bytes +653 | ||
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| 11 | It is a soft technique — the molecule survives largely intact — and it produces multiply charged ions from peptides and proteins, so a large molecule appears at a mass-to-charge ratio within the range of ordinary analysers. A single peptide therefore produces a series of peaks at successive charge states, deconvolved by software into one neutral mass.{{r|aebersold2003}} | 11 | It is a soft technique — the molecule survives largely intact — and it produces multiply charged ions from peptides and proteins, so a large molecule appears at a mass-to-charge ratio within the range of ordinary analysers. A single peptide therefore produces a series of peaks at successive charge states, deconvolved by software into one neutral mass.{{r|aebersold2003}} |
| 12 | 12 | ||
| + | 13 | == Mechanism == | |
| + | 14 | The applied potential draws the liquid into a cone from whose tip a fine spray of charged droplets emerges. Solvent evaporates, the droplets shrink until charge repulsion exceeds surface tension, and they divide. Ions are ultimately released either by field-driven ejection from very small droplets or by complete evaporation of the solvent around them.{{r|fenn1989}} | |
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| + | 16 | The charge states observed depend on the number of ionisable sites and on solution conditions. Acidic mobile phases favour protonation and positive-mode operation, which is why peptide LC-MS is usually run in positive mode with an acidic modifier.{{r|aebersold2003}} | |
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| 13 | == References == | 18 | == References == |
| 14 | {{reflist}} | 19 | {{reflist}} |