Reference standard: difference between revisions
Diff·revision 2 → 3·05:41, 15 Jul 2024
Difference between revision 2 and revision 3 of Reference standard. 5 lines changed; the page grew by 808 bytes.
| Revision 2 — 00:28, 7 Jul 2024 DeletionDeb (talk) add the ionisation mode to the mass-spectrometry description 1,189 bytes ±0 | Revision 3 — 05:41, 15 Jul 2024 CategoryBot (talk) bot: normalise citation format 1,997 bytes +808 | ||
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| 10 | Standards are described as primary or secondary. A primary standard is characterised by absolute methods without reference to another standard of the same substance; a secondary standard is qualified against a primary one and is what most laboratories actually use. Pharmacopoeial standards are the archetype of the first category.{{r|usp11}} | 10 | Standards are described as primary or secondary. A primary standard is characterised by absolute methods without reference to another standard of the same substance; a secondary standard is qualified against a primary one and is what most laboratories actually use. Pharmacopoeial standards are the archetype of the first category.{{r|usp11}} |
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| + | 12 | == What a standard supplies == | |
| + | 13 | A reference standard carries more than the substance. Its accompanying documentation states the assigned content — the mass fraction that is the substance of interest, which is not 100% — the identity data supporting the assignment, the storage conditions, and a retest or expiry date.{{r|usp11}} | |
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| + | 15 | Assigned content is the field most often misunderstood. A standard is not pure in the colloquial sense; it is a material whose composition has been determined, so that a known mass of it contains a known mass of analyte. Calibrating against a standard while ignoring its assigned content introduces a systematic error of exactly the magnitude of the water and counterion it contains — for a [[Trifluoroacetate counterion|trifluoroacetate-salted]] peptide, often 15–30%. | |
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| 12 | == References == | 17 | == References == |
| 13 | {{reflist}} | 18 | {{reflist}} |