What consumer-accessible tests can and cannot determine

What consumer-accessible tests can and cannot determine — that is the question, and I have not found it answered plainly anywhere I have looked.

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

• Column: C18, 2.1 x 100 mm, 1.7 um
• Mobile phase: 0.1% TFA in water / 0.1% TFA in acetonitrile
• Gradient: 7% to 60% organic over 32 minutes
• Detection: 220 nm
• Injection: 18 uL
• Sample: tirzepatide, reconstituted to 2.0 mg/mL, injected within an hour

The main peak integrates at 97.1% 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.

Enzyme assays: if you have an enzyme that reacts specifically with your compound, an enzyme-based assay can work. These are sometimes available commercially but are less common than antibody-based tests.

Picking up post #2: that is the part I would want checked first.

What physical quantity does the device measure? A colorimetric or lateral-flow method typically responds to a class of chemistry rather than to a specific molecule. It can distinguish "peptide present" from "nothing present" but generally cannot distinguish the intended peptide from a closely related one.