Amino acid analysis: difference between revisions
Diff·revision 8 → 9·12:43, 5 Mar 2025
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| Revision 8 — 00:04, 15 Feb 2025 Areapercent_Ayo (talk) fix a broken wikilink 2,621 bytes ±0 | Revision 9 — 12:43, 5 Mar 2025 CuriousCallum (talk) rm the assertion that two laboratories must agree; they need not 3,582 bytes +961 | ||
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| 1 | {{Infobox method | 1 | {{Infobox method |
| 2 | | name = Amino acid analysis | 2 | | name = Amino acid analysis |
| + | 3 | | subtitle = Compositional and quantitative method | |
| 3 | | Abbreviation = AAA | 4 | | Abbreviation = AAA |
| 4 | | Principle = Acid hydrolysis followed by chromatographic quantitation | 5 | | Principle = Acid hydrolysis followed by chromatographic quantitation |
| ⋮ | ⋮ | ||
| 20 | Absolute content follows from the total recovered amino acid mass against the sample mass taken. This is the figure that makes the method valuable for quantitation, and it is unaffected by water, counterion or residual solvent, all of which contribute to the weighed mass and none of which yields amino acids.{{r|usp1503}} | 21 | Absolute content follows from the total recovered amino acid mass against the sample mass taken. This is the figure that makes the method valuable for quantitation, and it is unaffected by water, counterion or residual solvent, all of which contribute to the weighed mass and none of which yields amino acids.{{r|usp1503}} |
| 21 | 22 | ||
| + | 23 | == Systematic errors == | |
| + | 24 | | Residue | Behaviour under standard hydrolysis | | |
| + | 25 | |---|---| | |
| + | 26 | | Asparagine, glutamine | Converted to aspartate and glutamate; reported combined | | |
| + | 27 | | Tryptophan | Substantially destroyed | | |
| + | 28 | | Cysteine | Destroyed unless derivatised beforehand | | |
| + | 29 | | Serine, threonine | Partially destroyed; corrected by extrapolation | | |
| + | 30 | | Valine, isoleucine | Slow to release; may be under-recovered at 24 h | | |
| + | 31 | ||
| + | 32 | These are not defects of a particular laboratory; they are properties of acid hydrolysis and are handled by convention. Serine and threonine losses are corrected by hydrolysing for several durations and extrapolating to zero time; valine and isoleucine by extending hydrolysis. Both corrections are established procedures rather than ad hoc adjustments.{{r|usp1052,ich_q2}} | |
| + | 33 | ||
| 22 | == References == | 34 | == References == |
| 23 | {{reflist}} | 35 | {{reflist}} |
| 24 | <ref name="usp1052">United States Pharmacopeia, General Chapter <1052>, ''Biotechnology-Derived Articles — Amino Acid Analysis''.</ref> | 36 | <ref name="usp1052">United States Pharmacopeia, General Chapter <1052>, ''Biotechnology-Derived Articles — Amino Acid Analysis''.</ref> |
| 25 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, ''Quality Attributes of Synthetic Peptide Drug Substances''.</ref> | 37 | <ref name="usp1503">United States Pharmacopeia, General Chapter <1503>, ''Quality Attributes of Synthetic Peptide Drug Substances''.</ref> |
| + | 38 | <ref name="ich_q2">International Council for Harmonisation, ''Q2(R2): Validation of Analytical Procedures'' (2023).</ref> | |
| 26 | <ref name="usp11">United States Pharmacopeia, General Chapter <11>, ''USP Reference Standards''.</ref> | 39 | <ref name="usp11">United States Pharmacopeia, General Chapter <11>, ''USP Reference Standards''.</ref> |
| 27 | 40 |