Purity claim inflation (revision 4)
Old revision·02:47, 10 Nov 2024·EpitalonEoin
| Purity claim inflation | |
|---|---|
| Distinguished from | Forgery — the figure here is genuine |
| Mechanism | Method choice, integration, and framing |
| Topic infobox · conventions | |
Purity claim inflation is the presentation of a purity figure in a manner that overstates what it establishes. Unlike forgery, the figure is generally genuine: what is misleading is the method that produced it, the way it was integrated, or the framing that presents it as answering a question it does not answer.[1]
The most consequential form is the substitution of purity for content. An area percent figure is normalised: it describes the proportion of detected material attributable to the main peak, and it is unaffected by how much peptide is present. A vial can be 99% pure and contain half the stated mass. Presenting purity where content is the relevant question is the commonest inflation of all.[1]
Mechanisms
[edit]| Mechanism | Effect on the number |
|---|---|
| Short gradient | Close-eluting impurities merge into the main peak |
| Generous integration boundaries | Shoulders counted as main peak |
| Detection wavelength chosen for the analyte | Impurities absorbing elsewhere under-detected |
| Reporting purity in place of content | Silence on how much peptide is present |
| Quoting the best of several determinations | Selection from a distribution |
| Aggregating related substances into one figure | Individual impurities concealed |
None of these is necessarily improper. A short gradient may be entirely appropriate for a well-characterised material; aggregate reporting of related substances is standard in some contexts. What makes a presentation inflationary is the gap between what the method establishes and what the figure is used to assert.[2]