Lyophilised Peptide Vials Hold More Than the Label: 17 Lots Measured

Across the 17 lots in our catalogue with both a label weight and a measured peptide content figure — certificates issued January to October 2026 by Janoshik Analytical, Testides (Toronto) and SideChain Analytics (Mississauga) — the median vial holds 114.0% of label, with a range of 99.4% to 137.3%, 16 of 17 lots at or above label, and exactly one below it. Every lot is indexed on our lab results page, and the full table is below.

This is not a novel observation. Panda Peptide publishes measured content per lot on a public certificates page, and Finnrick runs a vendor-testing programme that scores fill accuracy as a rated category with explicit tolerance bands. Anyone who reads certificates closely has seen overfill. What is missing from the public record is not the raw numbers but an explanation of why the direction is so consistent, and a statement of how wide the spread gets. That is what this page attempts, using data that can be checked against the certificates it came from.

What did we measure, and on how many lots?

Every active product in the catalogue was checked for two fields on its current certificate: the label weight printed on the vial, and the measured peptide content in milligrams reported by the laboratory. Twenty products are listed. Two are bacteriostatic water and carry no peptide content. One blend, GLOW, holds a purity figure but no content determination. That leaves 17 lots, shown below in ascending order of fill.

Lot / product	Label	Measured	% of label	Purity	Laboratory
Tesamorelin 10 mg	10 mg	9.94 mg	99.4%	95.19%	Testides
CJC-1295 (no DAC) + Ipamorelin	10 mg	10.08 mg	100.8%	95.80%	Testides
Tirzepatide 10 mg	10 mg	10.34 mg	103.4%	99.65%	Testides
Ipamorelin 10 mg	10 mg	10.68 mg	106.8%	99.673%	Janoshik #169441
Wolverine Blend (BPC-157 + TB-500)	10 mg	10.78 mg	107.8%	98.64%	Testides
BPC-157 10 mg	10 mg	10.99 mg	109.9%	99.64%	Testides
Tesamorelin + Ipamorelin (5+5)	10 mg	11.31 mg	113.1%	n/a (blend)	Janoshik #235914
Semax 10 mg	10 mg	11.32 mg	113.2%	99.138%	Janoshik #200391
Retatrutide 30 mg	30 mg	34.20 mg	114.0%	99.751%	Janoshik #210575
Semaglutide 10 mg	10 mg	11.42 mg	114.2%	99.664%	Janoshik #171488
Epithalon 10 mg	10 mg	11.75 mg	117.5%	99.004%	Janoshik #230585
Retatrutide 10 mg	10 mg	11.88 mg	118.8%	99.68%	Testides
TB-500 10 mg	10 mg	11.99 mg	119.9%	99.766%	Janoshik #147070
Semaglutide 5 mg	5 mg	6.05 mg	121.0%	99.247%	Janoshik #101805
Retatrutide 20 mg	20 mg	24.51 mg	122.6%	99.643%	Janoshik #207689
MOTS-C 10 mg	10 mg	12.97 mg	129.7%	99.5%	SideChain
GHK-Cu 50 mg	50 mg	68.67 mg	137.3%	99.93%	Testides

Purity figures are not directly comparable across laboratories or methods — Testides and Janoshik report HPLC-UV area-percent, SideChain reports chromatographic purity under Ph. Eur. 2.2.46 by HPLC-MS/MS. Blends report combined or per-component content. Certificate dates run January to October 2026.

One row needs an immediate caveat rather than a footnote. The GHK-Cu figure of 137.3% is under query with the laboratory. GHK-Cu is a copper complex with a molecular weight of 401.91 g/mol; the free tripeptide GHK is 340.38 g/mol, a difference of 18.1%. A content figure calculated on one basis and read against the other is wrong by exactly that much. Divide 68.67 mg by 1.181 and you get 58.2 mg, or 116.3% of label — squarely inside the rest of the distribution. We have asked Testides which basis the figure uses and have not yet had an answer, so we publish it as issued and flag it. Exclude that lot and the remaining 16 give a median of 113.6% and a mean of 113.3%, with the spread narrowing from 9.95 points of standard deviation to 8.32.

Why do lyophilised peptide vials contain more than the label says?

The label weight is a floor the filler has to clear, not a target it tries to hit, and three things that stand between a bulk powder and a sealed vial all push in the same direction.

Lyophilised vials are filled by solution volume, not by weighing powder. A bulk peptide is dissolved to a known concentration, dispensed by volume, frozen and dried. The mass in the vial is therefore the product of a concentration assay and a dispense volume, each with its own tolerance, and the dried cake is never weighed individually.

Material is lost between the bulk vessel and the sealed vial. Solution wets the filling line and the vial walls; dried cake adheres to the glass and the stopper. The standard response is to set the fill target above the label claim so the claim still holds at the low end of the tolerance band.

Synthetic peptides are not pure peptide by mass. A peptide purified by reversed-phase HPLC in a trifluoroacetic acid system leaves the column as a TFA salt; an ion-exchanged product is typically an acetate salt, and residual water persists in a lyophilised cake even after drying. For a basic peptide with several charged residues, counterion plus water can be a double-digit percentage of the powder's mass — the tesamorelin drug substance is the acetate salt, around 8% heavier than the free base.

What is net peptide content, and how is it different from the powder in the vial?

Net peptide content is the mass of the target peptide itself, excluding counterion, residual water, and any other peptide-related material in the vial. On a quantitative HPLC report it is derived from the area of the main peak read against a calibration curve built from a reference standard of known concentration. Because it is calculated from one peak, it counts only that peak's molecule.

Three consequences follow, and all three matter when comparing certificates.

Net content and gross powder weight are different quantities. A vial can hold 12 mg of powder and report 10 mg of peptide without anything being wrong; the gap is salt and water. A certificate that does not say which it reports is less useful than one that does.

Impurities subtract from content twice over. Peptide-related impurities — deletion sequences, oxidation products, truncations — are real mass in the vial, but they elute as separate peaks and are not counted toward the main peak's area. A lot with 5% related impurities therefore reports about 5% less net content than an otherwise identical lot at 100% purity, even with identical powder in the vial. Purity and content are separate measurements, but they are not independent: content is computed from the pure fraction only.

The reference standard sets the scale. A quantitative content figure is only as accurate as the material the curve was built from. Two laboratories using different reference standards, or the same standard corrected differently for its own salt and water, will produce different milligram figures from the same vial. We have seen that happen on our own lots, which is the subject of a separate article on cross-laboratory disagreement. The mechanics of reading these fields are set out in our guide to how to read a peptide COA.

Why was Tesamorelin the only lot below its label weight?

The single under-label lot is also the lowest-purity lot in the set, and the only one whose identity was established by retention time rather than by mass spectrometry. Tesamorelin 10 mg, Testides report ARUA-TESA-10-092026, run 26 September 2026: 95.19% purity by HPLC-UV at 214 nm, 9.94 mg content, identity by retention time within 0.54% of the laboratory's tesamorelin reference standard.

Part of why those facts travel together is mechanical. The laboratory integrated three peaks: tesamorelin at 18.54 minutes carrying 95.19% of the area, plus impurities of 4.14% at 18.04 minutes and 0.66% at 18.31 minutes. Content was calculated from the main peak alone, against a four-point curve with an R² of 0.99993. That 4.81% of related material is mass in the vial that does not count toward the content figure, so a lot at 99.7% purity with the same gross fill would report roughly 4.5% more net peptide. Low purity does not merely coexist with low content; on a main-peak quantitation it partly causes it.

The identity link is weaker, and we will not overstate it. Retention-time identity is a property of the method the laboratory ran, not of the lot — the same instrument would have given a retention-time identity on a 99.9% lot too. What is fair to say is narrower: all three observations come from a single injection on one HPLC-UV method with no mass spectrometer, and a single injection constrains how much weight any of them can bear.

The honest complication is that this lot is also our clearest cross-laboratory disagreement. A manufacturer-commissioned Janoshik Analytical assay on the same supplier lot, CS-te10-0616, report #198440 dated 1 July 2026, returned 99.174% purity and 11.56 mg — 115.6% of label, and firmly inside the overfill distribution. We publish the Testides figure because we commissioned it, and we publish the Janoshik figure because it exists. The claim "only one lot below label" is true of the certificates we lead with. It is not true of every certificate ever issued on these lots, and the lot in question is precisely the one where two laboratories disagree most.

Does another vendor's published data show the same pattern?

Yes, in direction but not in magnitude. Panda Peptide publishes a Janoshik verification table with measured content against stated strength for ten lots of batch 021026. Seven of those ten sit above label, the median is 108.3% and the mean 105.9%, with a range of 95.8% to 114.1%. The pattern is the same — overfill is the norm — but the distribution is tighter and centred about six points lower than ours.

Compound and label	thepeptide.ca	Panda Peptide	Gap
Retatrutide 10 mg	118.8%	110.3%	8.5 pts
Retatrutide 30 mg	114.0%	114.1%	0.1 pts
BPC-157 10 mg	109.9%	107.9%	2.0 pts
Semaglutide 10 mg	114.2%	108.8%	5.4 pts
TB-500 10 mg	119.9%	98.6%	21.3 pts
MOTS-C 10 mg	129.7%	100.0%	29.7 pts
GHK-Cu 50 mg	137.3%	108.8%	28.5 pts
CJC-1295 + Ipamorelin 10 mg	100.8%	95.8%	5.0 pts

Panda Peptide figures read from their public certificates page on 19 October 2026 (Janoshik verify table, batch 021026). Different lots, different supply chains, and in several cases different testing laboratories — this compares published numbers, not matched samples.

Pooling both vendors gives 27 lots, 23 of them at or above label, with a combined median of 110.3%. That is a stronger basis for the directional claim than either dataset alone, and it is still two Canadian vendors buying from a small number of Chinese manufacturers. The three largest gaps in the table — TB-500, MOTS-C and GHK-Cu — are the ones where our figures are highest, and in two of those three our own figure is the one under question. That is not a point in our favour, and we are not presenting it as one.

Would these lots pass a third-party fill-accuracy standard?

Not all of them, and the failures are all overfill. Finnrick's published methodology scores "how much material is in the container compared with the vendor's claim" and sets quantity tolerance bands by rating mode: ±35% in Purity focus, ±25% in Finnrick Standard, ±20% in Accuracy focus and ±15% in Finnrick Super strict. The page states that "underfill and overfill both fail when they exceed the allowed range."

Applying those bands to our 17 lots:

Tolerance band	Lots outside	Which lots
±15% (Super strict)	7 of 17	Epithalon, Retatrutide 10, TB-500, Semaglutide 5, Retatrutide 20, MOTS-C, GHK-Cu
±20% (Accuracy focus)	4 of 17	Semaglutide 5, Retatrutide 20, MOTS-C, GHK-Cu
±25% (Standard)	2 of 17	MOTS-C, GHK-Cu
±35% (Purity focus)	1 of 17	GHK-Cu

Our arithmetic against Finnrick's published tolerance bands, not a Finnrick rating. We have not been assessed by Finnrick and make no claim about what score we would receive.

Seven of seventeen outside the strictest band is not a flattering result, and the framing matters. A buyer reads overfill as free material; a tolerance standard reads it as a loss of control over the fill. Both describe the same number. A fill process landing anywhere between 99% and 137% of label is not calibrated, whichever direction the error points, and a 137% lot whose measurement basis is unconfirmed is an open question rather than a windfall.

What can this dataset not tell you?

It is not a market study, and nothing here supports a claim about peptide vials in general. The specific limits, stated plainly:

n = 17 is small. With seventeen observations, a median of 114.0% carries real uncertainty, and a single reclassified lot moves it by more than a point. The GHK-Cu query alone shifts the median to 113.6% and the mean by 1.4 points.

The lots are not a random sample. They are the lots we happen to stock, from a small number of suppliers, selected for sale rather than drawn for study. A supply chain that produced visibly bad lots would not be one we kept buying from, so the sample is filtered by its own commercial history.

Three laboratories and three method families are mixed in one table. HPLC-UV area-percent from Testides and Janoshik and HPLC-MS/MS under Ph. Eur. 2.2.46 from SideChain are not interchangeable, and we have direct evidence that two laboratories on one vial can differ by more than 14%. Some of the spread in the table is fill variation and some is measurement variation, and this dataset cannot separate them.

Most figures are single injections. There are no replicates, no error bars and no uncertainty budgets on these certificates. A content figure from one injection is a point estimate presented without its own precision.

Neither Testides nor Janoshik is an accredited laboratory, and we claim no accreditation. Several figures were commissioned by the manufacturer rather than by us, and those are marked on the individual product pages. Where both exist, we publish both.

Frequently asked questions

Does a vial measuring 118% of label mean the buyer gets 18% more peptide?

On that certificate, on that lot, the laboratory measured 18% more net peptide than the label states. It does not generalise to the next lot, and it is a single-injection point estimate with no stated uncertainty. It also says nothing about purity, identity or endotoxin, which are separate determinations. Treat it as one measurement on one vial, not as a property of the product line.

Is overfill a sign of a good manufacturer or a sloppy one?

Neither, by itself. Consistent overfill of a few per cent is ordinary practice and suggests the filler is clearing the label claim with a margin. A spread from 99% to 137% across one catalogue suggests the fill is not tightly controlled, and a third-party standard such as Finnrick's would score large overfill as a failure rather than a bonus. What distinguishes a careful supplier is the tightness of the distribution, not its centre.

Why do purity and content sometimes move in the same direction?

Because quantitative content on an HPLC report is calculated from the main peak alone. Peptide-related impurities are real mass in the vial but elute as separate peaks and are not counted. A lot at 95% purity therefore reports roughly 5% less net content than an otherwise identical lot at 100%, even with the same powder in the vial. Our Tesamorelin lot is the example in this dataset.

Why is the GHK-Cu figure flagged rather than simply reported?

Because GHK-Cu is a copper complex at 401.91 g/mol and the free tripeptide GHK is 340.38 g/mol, an 18.1% difference. A content figure calculated on one basis and read against the other is wrong by that margin, and 68.67 mg divided by 1.181 is 58.2 mg, or 116.3% of label — which would put the lot in the middle of the distribution rather than at its extreme. We have asked Testides which basis the figure uses and have not had an answer, so we publish it as issued and mark it as projected.

Do other vendors publish measured content per lot?

Some do. Panda Peptide publishes a Janoshik verification table with measured content against stated strength for each lot, and Finnrick operates a vendor-testing programme that rates fill accuracy against published tolerance bands. Measured content per lot is not unique to any one vendor, and a vendor claiming to be first to publish it is making a claim that is easy to check and wrong.

Can a measured content figure be compared across two laboratories?

Only with care. Our own lots show two laboratories differing on the same material by up to 16.3% — the Tesamorelin lot read 11.56 mg at Janoshik and 9.94 mg at Testides. Reference standards, calibration ranges, counterion correction and sample preparation all shift the number. That disagreement is set out in full in our article on cross-laboratory content discrepancy.

Does overfill change the legal status of these products in Canada?

No. Health Canada's public advisory of 9 April 2026 states that "research use only" labelling does not make a product legal or exempt it from regulatory requirements, and on 11 June 2026 the Superior Court of Québec granted Health Canada a permanent injunction against Canlab Research covering advertising through any website accessible from a Canadian IP address. Analytical quality and regulatory status are separate questions; a certificate describes a vial, not a legal position. Our guide to whether peptides are legal in Canada covers this.

What is net peptide content on a certificate of analysis?

Net peptide content is the mass of the target peptide itself, excluding counterion, residual water and any other peptide-related material in the vial. On a quantitative HPLC report it is derived from the area of the main peak read against a calibration curve built from a reference standard of known concentration, so it counts only that one molecule. It is not the same quantity as the gross weight of powder in the vial.

Sources

1. Certificates of analysis held by thepeptide.ca for the 17 lots tabulated above, issued January to October 2026 by Janoshik Analytical, Testides (Toronto) and SideChain Analytics (Mississauga). Indexed at thepeptide.ca/pages/lab-results.
2. Panda Peptide, Certificates of Analysis (Janoshik verify table, batch 021026), read 19 October 2026. pandapeptide.ca/certificates-of-analysis/
3. Finnrick, Methodology — inputs, safety standards and quantity tolerance bands. finnrick.com/methodology
4. Rory, "Testing the Peptide Testers," graymarket, 3 September 2025 — four vials from one retatrutide batch across multiple laboratories; the author describes the gap between laboratories as "a full 15% difference." graymarket.substack.com/p/testing-the-peptide-testers
5. Health Canada, public advisory, 9 April 2026: "Think twice before injecting peptides bought online: unauthorized products can seriously harm." recalls-rappels.canada.ca
6. Health Canada, "Health Canada obtains permanent injunction preventing Canlab Research's illegal sale of injectable peptides in Canada," July 2026. canada.ca
7. European Pharmacopoeia general chapter 2.2.46, Chromatographic separation techniques — the purity convention cited on the SideChain certificate.

Related reading

How to read a peptide COA · Two laboratories, one vial, a 9.7% gap · Where to get research peptides tested in Canada · Are peptides legal in Canada? · All lot results

Published 19 October 2026 by the thepeptide.ca research team. Figures derived from certificate data current at that date; lots and certificates change, and the lab results page carries the live set.