Chain of custody: difference between revisions
Diff·revision 11 → 12·05:46, 6 Jan 2025
Difference between revision 11 and revision 12 of Chain of custody. 6 lines changed; the page grew by 836 bytes.
| Revision 11 — 11:51, 25 Dec 2024 SPPS_Sorrel (talk) give the fields a compendially-complete certificate would carry 2,966 bytes ±0 | Revision 12 — 05:46, 6 Jan 2025 EndotoxinEd (talk) rm the ranking language; this wiki publishes no ranking 3,802 bytes +836 | ||
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| 1 | {{Infobox method | 1 | {{Infobox method |
| 2 | | name = Chain of custody | 2 | | name = Chain of custody |
| + | 3 | | subtitle = Sampling discipline | |
| 3 | | Records = Who held the sample, when, and under what conditions | 4 | | Records = Who held the sample, when, and under what conditions |
| 4 | | Purpose = Excludes substitution, tampering and undocumented excursion | 5 | | Purpose = Excludes substitution, tampering and undocumented excursion |
| ⋮ | ⋮ | ||
| 18 | 19 | ||
| 19 | This is the single most common confound in community testing. A result reported as characterising a supplier's material may be characterising the purchaser's storage, and the two are indistinguishable without a custody record. See [[Temperature excursion]]. | 20 | This is the single most common confound in community testing. A result reported as characterising a supplier's material may be characterising the purchaser's storage, and the two are indistinguishable without a custody record. See [[Temperature excursion]]. |
| + | 21 | ||
| + | 22 | == Why it is usually absent == | |
| + | 23 | The ordinary sequence for a community-submitted report is: material is bought; it is shipped by a carrier under unknown conditions; it is received and stored by the purchaser for some period; a vial is selected; it is posted to a laboratory. No step in that sequence is documented in a way that would satisfy a custody requirement.{{r|reports}} | |
| + | 24 | ||
| + | 25 | The consequences run in both directions and are not symmetric in the way people usually assume. Degradation in transit or storage produces a result worse than the material as shipped, so an unfavourable result from an uncontrolled chain is weak evidence against a supplier. A favourable result is less affected, since degradation does not improve purity — but it says nothing about whether that vial was representative. | |
| 20 | 26 | ||
| 21 | == References == | 27 | == References == |