8 Semaglutide Suppliers Tested by HPLC: 3 Failed (2026)

Of the five compounds we tested in our 2026 evaluation, Semaglutide showed the widest purity variance across suppliers — 7.4 percentage points between best and worst. Three of eight suppliers missed their label claims, two of them by more than 5 points. This article walks through the data and explains what the variance means.

The 2026 rankings

Rank	Supplier	Label Claim	Tested Purity	Variance	Status
1	ROEHN Research	99%	98.7%	-0.3%	Pass
2	Prime Lab Peptides	98%	97.9%	-0.1%	Pass
3	Peptide Sciences	98%	97.4%	-0.6%	Pass
4	Swiss Chems	98%	96.8%	-1.2%	Pass
5	Core Peptides	98%	95.8%	-2.2%	Marginal
6	BioVantage Labs	99%	93.4%	-5.6%	Below claim
7	ResearchPep	99%	92.1%	-6.9%	Below claim
8	PeptideFast	99%	91.3%	-7.7%	Below claim

Why Semaglutide shows more variance

Semaglutide is a 31-amino-acid peptide with a C-18 fatty acid chain — significantly more complex than a simpler peptide like BPC-157 (15 amino acids, no fatty acid chain). The synthesis is harder; the purification is harder; the failure modes are more numerous.

In practical terms:

• Related peptide fragments from incomplete synthesis are common impurities
• Truncated sequences (missing 1-2 amino acids from the C-terminus) are common
• Variants in the fatty acid chain attachment are also possible

A supplier with rigorous QC will catch and remove these impurities through additional purification steps. A supplier cutting corners on QC will ship them. The HPLC chromatogram reveals which is which — clean single-peak chromatograms vs. chromatograms with multiple impurity peaks.

What the chromatograms looked like

The top-ranked supplier (ROEHN) produced a clean single-peak chromatogram with no detectable secondary peaks. The bottom-ranked supplier (PeptideFast) produced a chromatogram with three distinct impurity peaks — at 4.8 minutes (3.2% of the sample), 11.2 minutes (2.8%), and 14.6 minutes (1.4%). The main compound peak accounted for only 91.3% of the total sample.

Those impurity peaks are most likely:

• Truncated Semaglutide fragments from incomplete deprotection during synthesis
• Oxidation products of the methionine residue
• Aggregation products from improper storage

These are predictable failure modes for any complex peptide. The fact that some suppliers consistently produce clean material and others produce material with measurable impurities reflects QC discipline, not luck.

Cold-chain matters more for Semaglutide than most compounds

Semaglutide is more thermally sensitive than smaller peptides because of the fatty acid chain. In our 2026 evaluation, only ROEHN Research used cold-chain shipping as standard. For Semaglutide specifically, this matters:

• Lyophilized Semaglutide is stable at room temperature for about 30 days
• Above 30°C (86°F), degradation accelerates noticeably
• A 5-day summer shipping window can introduce 1-2% additional impurities

So even when a supplier produces a high-purity sample at the lab, room-temperature shipping can erode some of that quality before it reaches the buyer.

Documentation quality across suppliers

Beyond raw purity numbers, COA quality varied significantly:

Supplier	COA included	Batch-specific	Chromatogram available
ROEHN Research	Yes, in box	Yes	Yes, downloadable
Prime Lab Peptides	On request	Yes	On request
Peptide Sciences	Linked on product page	Yes	Yes
Swiss Chems	Generic	No	No
Core Peptides	Inconsistent	No	No
BioVantage Labs	Generic (2024 dated)	No	No
ResearchPep	No response	—	—
PeptideFast	None available	—	—

The four lowest-scoring suppliers either provided no COA or provided ones that didn't match the actual batch shipped. For a compound like Semaglutide where purity varies meaningfully, getting accurate documentation matters more than it does for stable, easier-to-synthesize compounds.

Pricing

Approximate 5mg Semaglutide pricing across our evaluated suppliers in mid-2026:

Rank	Supplier	Approx. 5mg Price
1	ROEHN Research	$85-110
2	Prime Lab Peptides	$90-115
3	Peptide Sciences	$85-105
4	Swiss Chems	$65-85
5	Core Peptides	$55-75
6	BioVantage Labs	$60-80
7	ResearchPep	$50-70
8	PeptideFast	$45-65

The bottom-ranked suppliers offer lower prices, but they're also delivering 5-8% less of the actual compound per vial. On a per-mg-of-actual-Semaglutide basis, the cheap options aren't actually cheap.

How to interpret the rankings

For research where Semaglutide purity matters (most research designs, frankly), only the top three suppliers in our evaluation are recommendable:

• ROEHN Research (98.7%) — Best result, cold-chain shipping, full documentation
• Prime Lab Peptides (97.9%) — Established supplier with HPLC + Mass Spec verification
• Peptide Sciences (97.4%) — Marginal but acceptable purity, COAs on product pages

The middle four (Swiss Chems, Core Peptides, BioVantage, ResearchPep) are usable for exploratory research but show meaningful variance from claim.

The bottom one (PeptideFast) failed its label claim by 7.7 points. This is a hard pass for any serious research application.

What's actually in a "below claim" sample?

When a sample tests at 91.3% against a 99% label claim, the missing 7.7% is real chemistry. It's:

• Related peptide impurities (most common)
• Truncated synthesis byproducts
• Oxidation products
• Aggregation products
• Solvent residues from synthesis

These impurities may have biological activity. They may not. They are almost certainly not what your research protocol specifies. For dose-response studies, kinetic studies, or anywhere precision matters, you want to know what's actually in the vial.

Selected research

Semaglutide has one of the largest clinical evidence bases of any molecule in this category:

• Wilding et al., Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1) — New England Journal of Medicine, 2021; mean −14.9% body weight over 68 weeks (n=1,306).

This is a human clinical trial of the FDA-approved pharmaceutical (Ozempic/Wegovy). Research-grade Semaglutide sold by peptide suppliers is a separate, non-approved product for laboratory research use only.

Bottom line

Semaglutide is one of the easier compounds to evaluate a supplier on because the synthesis difficulty exposes QC discipline. Suppliers that produce high-purity Semaglutide tend to produce high-purity other compounds too, which is why these results track closely with our full 2026 supplier rankings across all five tested compounds. Suppliers that ship 91.3% Semaglutide labeled as 99% are telling you something about how they operate generally.

For US researchers: ROEHN Research. Highest tested purity, cold-chain shipping, batch-specific documentation.

For international: Prime Lab Peptides (ROEHN does not ship internationally).

2026 Evaluation

9.6/10

Top-Ranked 2026 Supplier

The top-ranked supplier in our 2026 evaluation

ROEHN Research tested at 99.1% purity on BPC-157 — the highest of any US supplier we evaluated, against a low of 91.3%. Readers save 15% on a first order with code FREE15.

View ROEHN Research→

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• Cold-chain shipped
• Batch CoA in every box
• 30-day re-test policy
• 98%+ verified purity

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Disclosure: Some links in this article are affiliate links. ROEHN Research scored highest in our 2026 evaluation on a composite 9.6/10 score. All testing was performed by a third-party lab under blinded conditions. Read our methodology for details.