What a c-peptide test costs: $75–$150 for HPLC purity, $150–$350 for LC-MS ID, $450–$900 for full characterization, plus vial prices and rush fees.
A third-party HPLC purity assay on a C-peptide reference material typically runs $75–$150 per sample; LC-MS identity confirmation adds $150–$350; a full characterization panel (RP-HPLC purity, mass confirmation, amino acid analysis, water content, counter-ion, residual solvents) lands between $450 and $900 at most US contract labs, with 5–10 business day turnaround and a 1.5–2× surcharge for 48-hour rush. The material itself — human C-peptide, 31 residues, ~3020 Da, lyophilized — generally sells at $55–$110 for a 5 mg vial at single-unit pricing, with per-mg cost falling 30–50% at 10-vial quantities. If your supplier already provides a lot-specific certificate of analysis, most of that testing spend is redundant.
One disambiguation before you read further: if you arrived looking for the price of a clinical C-peptide blood draw, that is a diagnostic service billed by a medical laboratory and ordered by a clinician. This page is about the cost of analytically characterizing C-peptide as a research reference material. Different product, different buyer, different regulations. Nothing here applies to a patient sample.
Contract lab pricing in the US clusters tightly. These are single-sample, non-contract rates as of 2026; annual-volume agreements commonly cut 15–25%.
Add shipping a sample on dry ice — $60–$180 per outbound package domestically — and a full outside panel on one lot realistically costs $550 to $1,100 all-in, against a vial that cost $80.
A 5 mg vial labeled 98% purity does not contain 5 mg of C-peptide. Work the arithmetic:
Your $80 vial is $19.28 per effective mg, not $16.00 — a 20% gap. Two suppliers quoting $80 and $95 can invert once net peptide content is known, and the only way to know it is AAA or a supplier who reports it on the certificate. A lot at 96% HPLC with 3% water and 4% TFA delivers more peptide than a "99%" lot at 11% water and 14% TFA.
The cheapest defensible C-peptide is almost never the cheapest vial. It's the vial whose certificate of analysis lets you skip $600 of confirmatory testing.
A COA that says "Purity: >98%" with no lot number, no date, and no chromatogram saves you nothing — you will re-test, and you should. A COA worth its weight includes:
Our approach to lot documentation is described on the quality page, and the framing that governs how all of this material may be used is on research use only.
This is the part that costs us margin to say plainly.
You do not need a $900 panel if: you are running a method-development or column-conditioning experiment where identity is confirmed in-run by your own LC-MS, your assay tolerates ±10% on concentration, or you are consuming under 10 mg per year. In that case, buy the vial, run one 20 µL injection on your own system, compare retention time and mass to the supplier chromatogram, and move on. That costs you roughly $8–$25 in solvent, column lifetime, and instrument time.
You should not order a rush panel at 2× rate unless a grant deadline or an audit date genuinely forces it. The 48-hour surcharge on a $700 panel is $700 for two saved days.
Peptide mapping on a 31-mer is usually overspending. A clean parent-ion mass plus a single sharp HPLC peak answers the identity question. Mapping earns its $1,200 when you suspect deamidation, oxidation, or a specific sequence variant — not as a default.
Endotoxin testing is irrelevant to most chemistry. If the material never touches a cell, that $110 buys nothing.
Certified reference materials (CRMs) are a different price tier entirely. A metrologically traceable, ISO 17034-accredited C-peptide CRM can run $400–$1,400 for 0.5–1 mg, sometimes 20× the per-mg cost of research-grade material. If you are calibrating a quantitative assay whose results will be compared across institutions, that premium is the point and research-grade material is the wrong purchase. If you are not, you are paying for a traceability chain you will never invoke.
Repeat-purchase spend gets destroyed by things that never appear on a quote.
A small lab consuming 50 mg of C-peptide per year, buying at 10-vial pricing, qualifying one new lot annually with an outside HPLC + MS check, and paying cold-chain freight four times:
The same lab running a full panel on every lot instead: add roughly $2,400–$3,600, for information that the supplier's own certificate already supplied. Spend that on a second lot for cross-comparison instead — it answers more questions.
If you want the actual lot documentation for current inventory before committing to a PO, ask for it through contact; a supplier who will not send a redacted sample COA pre-purchase is telling you something about the one you would receive after.
Supplied strictly for in-vitro laboratory research by qualified researchers and institutions. Not a drug, food, cosmetic or dietary supplement. Not for human or veterinary consumption. Not evaluated by the FDA.
Purity, identity and lot number, documented for the exact vial you receive.