The molecule we identify.
The assays we run on Semaglutide.
The failure modes we see most.
- 01Under-dosed vials. Net Peptide Content commonly falls 12-25 % below label when the supplier reports gross peptide salt rather than active mass. A 5 mg vial may carry 3.8 mg of active.
- 02Truncated sequences (des-Arg, des-Lys) co-elute close to main peak and inflate apparent purity unless the HPLC gradient is tuned. Look for related-peptide peaks at RT ± 0.3 min of the main peak.
- 03TFA carryover above 3 %. Causes injection-site stinging and adds significant mass that's mis-counted as active.
- 04Off-mass MS signal (Δ +14 or +28 Da) indicates methylated or oxidized variants from poorly controlled synthesis.
- 05Endotoxin pass at the lot level but fail at the reconstituted-vial level when bacteriostatic water isn't truly bacteriostatic. We test the reconstituted product on request.
Transparent panels for Semaglutide.
Identity (LC-MS) + HPLC purity % + Net Peptide Content on one public COA — the baseline every batch should carry, with accession number.
- Identity (LC-MS/MS)
- HPLC purity % + impurity peaks
- Net Peptide Content
- Public COA + accession #
- 5-7 day turnaround
COA Essentials plus USP <85> endotoxin (LAL) and USP <71> sterility. The injectable-grade package.
- Everything in COA Essentials
- Endotoxin (LAL) USP <85>
- Sterility USP <71>
- Conformity Testing +1
- 5-7 day turnaround
Everything above plus heavy metals (ICP-MS, USP <232>) and USP <61> bioburden. The full vendor / compounding COA.
- Everything in Injectable Safety
- Heavy metals (ICP-MS) USP <232>
- Bioburden (USP <61>)
- Conformity Testing +1
- 5-7 day turnaround
Semaglutide testing — the common questions.
What's the difference between HPLC purity and Net Peptide Content for Semaglutide?+
HPLC purity tells you what fraction of the chromatogram peaks is the main Semaglutide peak vs related-impurity peaks. It's a relative measurement of peak area. Net Peptide Content tells you what fraction of the dry mass in the vial is actual active Semaglutide vs TFA / acetate counter-ions, water of hydration, and inorganic salts. A vial can have 99 % HPLC purity and only 78 % Net Peptide Content — both numbers matter for different reasons. Public COAs that only report purity are leaving out the dose-accuracy half of the story.
Do you confirm the exact molecular mass by MS?+
Yes. LC-MS identity confirmation is folded into COA Essentials ($289) and every panel above it — Identity is part of the base COA for every peptide. We compare the observed molecular ion against the theoretical monoisotopic mass of 4113.58 Da and report mass accuracy in ppm. The full charge-state envelope is captured; any off-mass species (oxidations, methylations, sequence truncations) are flagged with their observed mass.
What's a reasonable TFA residual for Semaglutide?+
Industry-typical TFA / acetate counter-ion content runs 1-3 % w/w of the dry mass. Above 5 % usually indicates inadequate post-synthesis ion-exchange and causes both dose-accuracy distortion (active mass is over-estimated by TFA mass) and injection-site stinging. We report exact % w/w with the method documented on the COA.
Can you test reconstituted Semaglutide vials?+
Yes. Ship reconstituted vials cold-packed in the original BAC water or sterile saline. We can run NPC, LC-MS identity, and endotoxin on the reconstituted product, which is the most meaningful test for actual user exposure — but cold-chain and shipping volume make it less common than lyophilized testing. Pricing matches the dry vial panel.
Is sterility testing actually required for research peptides?+
Not legally required for research-use-only material, but the USP <71> sterility test is what separates injectable-grade material from research powder. Brands selling lyophilized peptide vials to consumers / clinics frequently include sterility because the regulatory expectation around injectables is what their buyers ask for. The 14-day membrane-filtration cultured-broth method is included in the Vendor Full QC panel.
Sample size — how much Semaglutide do you need?+
For COA Essentials ($289): single 2 mg sealed lyophilized vial. For Injectable Safety ($599): the same single vial — we re-use the dissolved material across HPLC, LC-MS, NPC, and TFA. For Vendor Full QC ($849): two additional vials (one for sterility, one for endotoxin, both destructive tests). Ship by overnight courier with original packaging — lot, batch, and seal integrity matter for chain of custody.
Other glp-1 receptor agonist testing —
Dual GIP / GLP-1 agonist (Mounjaro / Zepbound active). Same instrument stack — HPLC purity, MS identity, NPC, TFA, endotoxin.
Triple GLP-1 / GIP / glucagon agonist in clinical development. Same panel — HPLC + MS + NPC + TFA.
Full peptide-testing menu — all assays, all bundles, all compounds we cover beyond GLP-1.
Verify the vial. Sign the COA.
HPLC purity, LC-MS identity, NPC, TFA, endotoxin, sterility — Houston bench, public COA, transparent pricing.