Coming back to: What consumer-accessible tests can and cannot determine

Asking directly, because I could not find a straight answer: What consumer-accessible tests can and cannot determine

Posting the method first, because I know what the first three replies will otherwise be.

• Column: C18, 3.0 x 150 mm, 2.6 um
• Mobile phase: 0.1% TFA in water / 0.1% TFA in acetonitrile
• Gradient: 7% to 56% organic over 29 minutes
• Detection: 280 nm
• Injection: 17 uL
• Sample: retatrutide, reconstituted to 0.5 mg/mL, injected within an hour

The main peak integrates at 96.6% of total area. There is a small feature on the trailing edge that I cannot decide is a shoulder or a baseline artefact, and that is what I am actually asking about.

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

Worth separating two things that post #2 runs together.

What you can use home tests for: confirmation that a solution contains peptide (as opposed to being saline alone), rough screening for very different compounds (semaglutide versus totally unrelated compound). What you cannot use them for: precise purity assessment or verification that the identity is correct.

Immunoassay limitations: tests that use antibodies have cross-reactivity limitations. An antibody raised to semaglutide will cross-react to some degree with tirzepatide and other structurally similar compounds. The test result conflates them.

On post #4 — agreed on the reasoning, with one qualification.

Precision of home tests: most consumer-accessible devices are not precise to the level people want ("is this 99% pure or 97% pure"). They give a yes/no or a rough category, not a quantitative number.