Area percent purity: difference between revisions
Diff·revision 21 → 22·14:14, 13 Jul 2025
Difference between revision 21 and revision 22 of Area percent purity. 5 lines changed; the page grew by 616 bytes.
| Revision 21 — 03:14, 19 Jun 2025 ColdChainCleo (talk) correct the flow rate — the source gives it in mL/min 6,764 bytes +166 | Revision 22 — 14:14, 13 Jul 2025 AnalyticalAnnie (talk) correct the resolution formula — the denominator is the sum of the widths 7,380 bytes +616 | ||
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| 50 | Reading 99.0% as "4.95 mg of peptide" overstates the content by roughly 18%. This arithmetic is the whole reason [[Peptide content]] exists as a separate determination, and it is why a purity figure and a content figure appearing together on one certificate — 99% and 83% — are consistent rather than contradictory.{{r|usp1503}} | 50 | Reading 99.0% as "4.95 mg of peptide" overstates the content by roughly 18%. This arithmetic is the whole reason [[Peptide content]] exists as a separate determination, and it is why a purity figure and a content figure appearing together on one certificate — 99% and 83% — are consistent rather than contradictory.{{r|usp1503}} |
| 51 | 51 | ||
| + | 52 | == Reporting conventions and comparison == | |
| + | 53 | Three conventions make area percent figures comparable, and their absence is the ordinary reason two figures for one lot differ. | |
| + | 54 | ||
| + | 55 | First, '''report the method with the figure''': column chemistry, gradient, flow rate, detection wavelength, injection volume. Second, '''itemise related substances individually''' rather than reporting a single aggregate impurity figure — an aggregate conceals whether one impurity is at 0.9% or nine are at 0.1%, which are different situations. Third, '''state the integration threshold''', because it determines what was counted at all. | |
| + | 56 | ||
| 52 | == References == | 57 | == References == |
| 53 | {{reflist}} | 58 | {{reflist}} |