High-performance liquid chromatography: difference between revisions
Diff·revision 15 → 16·07:12, 19 Jan 2025
Difference between revision 15 and revision 16 of High-performance liquid chromatography. 5 lines changed; the page grew by 646 bytes.
| Revision 15 — 02:58, 3 Jan 2025 SurmountSurma (talk) sentence case in headings per PP:MOS 4,718 bytes ±0 | Revision 16 — 07:12, 19 Jan 2025 DulaglutideDug (talk) correct the flow rate — the source gives it in mL/min 5,364 bytes +646 | ||
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| 40 | The last caveat is the one most often overlooked. Species that do not absorb at the detection wavelength — inorganic salts, many sugars, water — are invisible, and species that do not elute within the run remain on the column and are simply absent from the chromatogram. A clean trace is evidence about what was detected, not about what was present.{{r|usp1503}} | 40 | The last caveat is the one most often overlooked. Species that do not absorb at the detection wavelength — inorganic salts, many sugars, water — are invisible, and species that do not elute within the run remain on the column and are simply absent from the chromatogram. A clean trace is evidence about what was detected, not about what was present.{{r|usp1503}} |
| 41 | 41 | ||
| + | 42 | == Why method conditions must be stated == | |
| + | 43 | Two determinations of the same material can differ substantially if the methods differ, and the difference is not error: the methods are answering different questions.{{r|usp621}} | |
| + | 44 | ||
| + | 45 | A short gradient completes quickly and resolves poorly, merging close-eluting impurities into the main peak and returning a higher purity figure. A longer, shallower gradient resolves them and returns a lower one. Both figures are correct for their method. Similarly, detection at 280 nm rather than 214 nm under-detects impurities lacking aromatic residues, and column chemistry alters selectivity as well as retention. | |
| + | 46 | ||
| 42 | == References == | 47 | == References == |
| 43 | {{reflist}} | 48 | {{reflist}} |