Temperature excursion: difference between revisions
Diff·revision 10 → 11·11:28, 8 Jul 2025
Difference between revision 10 and revision 11 of Temperature excursion. 14 lines changed; the page grew by 812 bytes.
| Revision 10 — 20:43, 25 Jun 2025 RetatrutideRuben (talk) expand §Assessment and disposition 10,953 bytes +836 | Revision 11 — 11:28, 8 Jul 2025 RepackRadek (talk) add the collapse-temperature point, sourced 11,765 bytes +812 | ||
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| 1 | {{Infobox concept | 1 | {{Infobox concept |
| 2 | | name = Temperature excursion | 2 | | name = Temperature excursion |
| + | 3 | | subtitle = Storage deviation | |
| 3 | | image = cold-chain.svg | 4 | | image = cold-chain.svg |
| 4 | | caption = An excursion is defined against a labelled range, so the same profile may be an excursion for one product and compliant for another. | 5 | | caption = An excursion is defined against a labelled range, so the same profile may be an excursion for one product and compliant for another. |
| ⋮ | ⋮ | ||
| 55 | 56 | ||
| 56 | The corresponding position for lyophilised research peptides is that no such allowance exists in a documented form. Supplier storage statements are recommendations, and the periods sometimes quoted for ambient tolerance are not supported by an identifiable stability study. The physical argument for the robustness of a dry cake is set out at [[Lyophilisation]] and is a reason to expect tolerance, not a substitute for having measured it.{{r|ppexcursion}} | 57 | The corresponding position for lyophilised research peptides is that no such allowance exists in a documented form. Supplier storage statements are recommendations, and the periods sometimes quoted for ambient tolerance are not supported by an identifiable stability study. The physical argument for the robustness of a dry cake is set out at [[Lyophilisation]] and is a reason to expect tolerance, not a substitute for having measured it.{{r|ppexcursion}} |
| + | 58 | ||
| + | 59 | == Quantifying an excursion == | |
| + | 60 | Where an excursion consists of warming, its cumulative effect is summarised by the mean kinetic temperature. For intervals of duration ''t''<sub>i</sub> at absolute temperatures ''T''<sub>i</sub>: | |
| + | 61 | ||
| + | 62 | {{math|T_{MKT} = (ΔH/R) ÷ [ −ln( Σ t_{i} e^{−ΔH/(R T_{i})} ÷ Σ t_{i} ) ]}} | |
| + | 63 | ||
| + | 64 | with ΔH/R taken as 10,000 K by convention.{{r|haynes1971,usp1079}} | |
| + | 65 | ||
| + | 66 | A realistic worked case demonstrates the property that makes the statistic useful. A consignment labelled for storage at 2–8 °C is held for 30 days, of which 96 hours are spent at 22 °C — a courier depot over a long weekend, repeated — and the remaining 624 hours at 5 °C. | |
| + | 67 | ||
| + | 68 | The time-weighted arithmetic mean is | |
| + | 69 | ||
| + | 70 | {{math|(96 × 22 + 624 × 5) ÷ 720 = (2112 + 3120) ÷ 720 = 7.27 °C}} | |
| 57 | 71 | ||
| 58 | == References == | 72 | == References == |