Cold chain: difference between revisions
Diff·revision 9 → 10·16:04, 10 Sep 2024
Difference between revision 9 and revision 10 of Cold chain. 16 lines changed; the page grew by 1,701 bytes.
| Revision 9 — 08:45, 26 Aug 2024 CDMO_Caradoc (talk) add the data-logger point: an unlogged shipment has no excursion record 8,537 bytes +927 | Revision 10 — 16:04, 10 Sep 2024 CounterfeitCato (talk) give the vial sizes in millilitres of nominal capacity 10,238 bytes +1,701 | ||
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| 1 | {{Infobox concept | 1 | {{Infobox concept |
| 2 | | name = Cold chain | 2 | | name = Cold chain |
| + | 3 | | image = cold-chain.svg | |
| + | 4 | | caption = A cold chain is a series of custody transfers, each of which is a candidate point of failure and each of which is expected to leave a temperature record. | |
| 3 | | Scope = Manufacture, warehousing, freight, last mile, end use | 5 | | Scope = Manufacture, warehousing, freight, last mile, end use |
| 4 | | Principal controlled variable = Temperature | 6 | | Principal controlled variable = Temperature |
| ⋮ | ⋮ | ||
| 51 | ; Chemical threshold indicators : Change colour irreversibly when a threshold is crossed. Freeze indicators of this type are the standard means of detecting a freezing excursion in vaccine distribution. | 53 | ; Chemical threshold indicators : Change colour irreversibly when a threshold is crossed. Freeze indicators of this type are the standard means of detecting a freezing excursion in vaccine distribution. |
| 52 | ; Time–temperature integrating indicators : Accumulate a colour change as a function of both temperature and time, approximating the cumulative thermal exposure that matters for degradation. | 54 | ; Time–temperature integrating indicators : Accumulate a colour change as a function of both temperature and time, approximating the cumulative thermal exposure that matters for degradation. |
| + | 55 | ||
| + | 56 | |+ What each monitoring device can and cannot establish | |
| + | 57 | | !Device | Establishes | Cannot establish | | |
| + | 58 | |---|---|---| | |
| + | 59 | | Electronic data logger | Full time–temperature profile; permits mean kinetic temperature | Product temperature, unless placed in the payload | | |
| + | 60 | | Minimum–maximum thermometer | Extremes reached | Duration at any temperature | | |
| + | 61 | | Freeze indicator | That a freezing threshold was crossed | By how much, or for how long | | |
| + | 62 | | Time–temperature integrator | Cumulative exposure above a reference | The shape of the profile | | |
| + | 63 | | Vaccine vial monitor | Cumulative heat exposure at the individual vial | Freezing exposure | | |
| + | 64 | ||
| + | 65 | === Calibration and traceability === | |
| + | 66 | A temperature record is only as good as the calibration of the instrument that produced it. Compendial guidance on monitoring devices expects calibration traceable to a national metrology institute, at intervals appropriate to the device, and at points within the range of interest rather than only at ambient temperature. A logger calibrated at 25 °C and used at 5 °C may carry an error larger than its stated accuracy.{{r|usp1118}} | |
| + | 67 | ||
| + | 68 | The conventional expectation for a logger used in 2–8 °C distribution is an accuracy of ±0.5 °C across that range. This is an expectation drawn from qualification practice and from performance specifications for prequalified devices; it is not a requirement imposed by a general chapter, and articles asserting it as a standard have been corrected on this point.{{r|whotrs961,usp1118}} | |
| 53 | 69 | ||
| 54 | == References == | 70 | == References == |