HPLC vs Mass Spec on a Peptide COA: Why 99% Purity Does Not Prove Identity

“My COA says 99%, so I am fine” is the most expensive sentence in this market. HPLC purity is a ratio calculated inside the sample: main-peak area divided by total peak area, measured by UV absorbance near 214 to 220 nm where the peptide bond absorbs. It tells you the material is homogeneous. It cannot tell you which molecule that homogeneous material is, because a flawlessly synthesised batch of the wrong compound elutes as one clean, symmetric, 99%-pure peak. Identity is a separate measurement on a separate instrument: mass spectrometry weighs the molecule and compares the observed mass against the theoretical mass calculated from the claimed amino-acid sequence. Purity is a percentage; identity is a number in daltons. The deciding point for anyone vetting a vendor is therefore not the size of the purity figure but whether the certificate shows an expected mass, an observed mass, and a delta you can check yourself.

Published 2026 - For research use only (RUO). Nothing here is medical advice, a dosing protocol, or a human-use recommendation.

In a hurry? Jump to how Pepora scores on the checklist →

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What HPLC purity actually measures, and the four things it cannot see

Reversed-phase HPLC separates a peptide mixture by hydrophobicity: the sample is loaded onto a C18 or C4 column and eluted with an increasing organic gradient, so components leave the column at different times. A UV detector set near 214 nm records absorbance, and the software integrates the resulting peaks. Purity is then reported as area normalisation - the main peak’s area as a share of the total integrated area (Mant and Hodges, Methods Mol Biol 2007, PMID 18604941).

Read that definition slowly, because four consequences follow directly from it, and each one is a way a 99% number can be true and useless.

1. The percentage is relative to the sample, not to the label. Area normalisation has no external reference. It never asks “is this the peptide on the vial?” It asks “how much of what I saw was the biggest thing I saw?” A pure batch of a cheaper peptide scores identically to a pure batch of the correct one.

2. Anything without a chromophore is invisible. Detection at 214 nm sees peptide bonds. Residual water, inorganic salts, and the trifluoroacetate counterion left over from purification contribute little or no absorbance at that wavelength, so they are largely absent from the denominator. This is why net peptide content, established by mass balance, is routinely lower than the vial’s gross fill weight, and why purity and content are not the same claim.

3. Co-eluting impurities are counted as product. Retention on a reversed-phase column is driven by the summed hydrophobicity of the side chains. A deletion sequence missing one small polar residue, or a diastereomer differing only in stereochemistry at a single centre, can shift retention so little that it hides under the main peak and is integrated as part of it. The published work on predicting peptide retention times is explicit that side-chain character and terminal groups dominate the retention outcome (Tripet, Mant, Krokhin and Hodges, J Chromatogr A 2007, PMID 17187811), which is precisely why single-residue differences are not reliably resolved.

4. A percentage without a chromatogram is unauditable. If you cannot see the baseline, the gradient, the axes, and the shoulder peaks, you are trusting a typed number. A visible chromatogram is where an integration that quietly excluded the front-running junk becomes obvious.

None of this makes HPLC weak. Purity is the only routine measurement that quantifies how much related junk rides along with the target, and mass spectrometry is bad at that job because different molecules ionise with wildly different efficiency, so MS peak heights are not proportions. HPLC is simply answering a question that is not the question most buyers think it is answering.

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What the mass spec trace proves, and its own two blind spots

Mass spectrometry ionises the molecule and measures mass-to-charge ratio. In peptide QC the standard approach is electrospray ionisation, which produces multiply protonated ions, so a single compound shows up as a family of signals: [M+H]+, [M+2H]2+, [M+3H]3+ and upward. Software deconvolutes that charge-state envelope into one neutral mass, and that number is compared against the theoretical mass calculated from the sequence. This is the established method for confirming the authenticity and integrity of a synthetic peptide (Chrone, Lorentzen and Højrup, Methods Mol Biol 2024, PMID 38997482).

Two practical points decide whether you can actually read the report.

Average versus monoisotopic. Average mass uses natural isotopic abundances and is what you get from a molecular formula in a database. Monoisotopic mass counts only the lightest isotope of each element and is what a high-resolution instrument resolves. For BPC-157 the two values are about 1419.5 Da and 1418.70 Da respectively (PubChem CID 9941957) - a gap large enough that comparing the wrong pair invents a mismatch that is not there. A competent report says which convention it is using.

Tolerance. On a low-resolution instrument, a nominal match within roughly 1 Da is the working convention rather than a figure any standards body defines. On a high-resolution instrument the answer is quoted in parts per million, and sub-5 ppm accuracy is achievable for peptides in the 1200-1500 Da range given internal calibration and strong peak intensities (Bahr and Karas, Rapid Commun Mass Spectrom 1999, PMID 10368979).

Now the blind spots, because a vetting guide that oversells MS is just a different flavour of the same error.

Isobars and isomers survive intact-mass analysis. Leucine and isoleucine have identical elemental composition and identical mass; no mass accuracy whatsoever separates them, and distinguishing them requires side-chain fragmentation in tandem MS. Lysine and glutamine differ by about 0.036 Da, invisible at low resolution and trivial at high resolution (PMID 10368979). A scrambled sequence built from the same residues, or a D-amino-acid substitution, is exactly isobaric with the correct peptide and passes an intact-mass check cleanly. Confirming sequence, as opposed to mass, requires MS/MS fragmentation or de novo sequencing - the same technique the forensic literature uses when it has to prove what an unknown vial really contains.

MS peak intensity is not a purity figure. Ionisation efficiency varies by orders of magnitude between compounds, so the absence of an impurity signal is weak evidence of its absence, and the relative heights in a spectrum are not a purity figure.

Which is the whole point: the two measurements are complements, not substitutes. HPLC without MS is a proportion with no molecule attached. MS without HPLC is a molecule with no proportion attached. Our field guide to reading a COA walks the remaining fields; this page is about why these two in particular cannot stand in for each other.

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Delta-mass forensics: what the documented cases actually showed

The reason to demand the MS page is that the published record shows identity failures that a purity percentage would have sailed straight past. These are the cases with real instrument data behind them.

The glycine-analogue case. Analysts at Poland’s National Medicines Institute examined a seized injection vial using liquid chromatography coupled to high-resolution quadrupole time-of-flight tandem MS. The contents were not GHRP-2. They were a novel heptapeptide, reported at 874.02 Da and identified as a glycine analogue of GHRP-2 (Popławska and Błażewicz, Drug Test Anal 2019, PMID 30051972). Worth doing the arithmetic yourself, because it does not close cleanly: GHRP-2 (pralmorelin) has a monoisotopic mass of about 817.43 Da (PubChem CID 6918245), a glycine residue adds 57.02 Da, and a Gly-extended analogue therefore calculates to roughly 874.45 Da. The published 874.02 sits about 0.4 Da below that, so read the reported figure as approximate rather than as an exact match to theory. The finding itself is not in doubt: the vial contained a different molecule from the one on the label, and a homogeneous batch of it would report as high-purity material on any HPLC.

The +71 Da case. A team spanning the German Sport University Cologne, the Norwegian Doping Control Laboratory and ISAS Dortmund analysed black-market growth-promoting products and found a modified growth hormone carrying one extra N-terminal alanine: monoisotopic mass 22,195 Da against 22,124 Da for the endogenous 22 kDa isoform, a delta of 71 Da confirmed by top-down and bottom-up high-resolution MS. The same study identified three N-terminally glycine-extended GHRP analogues - Gly-GHRP-6, Gly-GHRP-2 and Gly-Ipamorelin - with two of the structures confirmed against custom-synthesised reference material (Krug, Thomas, Thevis et al., Growth Horm IGF Res 2018, PMID 29864719).

The nothing-in-the-vial case. Forensic chemists at the University of Copenhagen ran 36 seized peptide and protein samples through a four-method workflow including LC-TOF-MS. Fifteen contained a prohibited doping substance, twelve contained substances not on the Danish list, and nine contained no peptide or protein at all (Høj, Rasmussen, Dalsgaard and Linnet, Drug Test Anal 2021, PMID 33686802). Twenty-five percent of a seized sample set was material with nothing to be pure of. The converse also occurs: a German doping-control group used LC-MS to find GHRP-2 present at roughly 50 micrograms per tablet in a product sold as an ordinary over-the-counter nutritional supplement, where the label named no peptide at all (Thomas, Thevis et al., Drug Test Anal 2010, PMID 20878896). In both directions, the label was not the molecule.

The GLP-class case, stated honestly. A 2024 peer-reviewed purchase study bought GLP-class peptide vials from online sellers operating without prescription and analysed what arrived. Mass spectrometry did confirm the target compound was present - the characteristic [M+4H]4+ signal was there. The failure was elsewhere and it was severe: against labels claiming 99%, measured purity came back at 14.37%, 8.97% and 7.70%, while total content ran 28.6% to 38.7% above the stated amount, and one sample carried an endotoxin burden of 8.95 EU/mg (Ashraf, Mackey, Vida et al., J Med Internet Res 2024, PMID 39509151). Note what this inverts: here identity passed and purity collapsed by more than 90 percentage points from the claim. It is the mirror image of the GHRP case, and together they show that either measurement alone leaves a hole big enough to drive a business through.

One caution on this cluster of compounds. Forum posts frequently circulate claims that specific gray-market GLP-class vials mass-spec’d at molecular weights far off expectation. Some may be true, but we could not locate an independently published trace confirming any specific instance, so we are not citing one. What is documented at regulator level is adjacent and sufficient: the FDA has stated that salt forms such as semaglutide sodium and semaglutide acetate are different active ingredients from the base form in the approved product (FDA, GLP-1 concerns statement), and it has warned about counterfeit product recovered from the legitimate US supply chain (FDA counterfeit alert, December 2023). A salt-form swap is exactly the kind of substitution a purity percentage is structurally incapable of reporting.

Delta-mass quick reference

When an observed mass misses the expected value, the size of the gap narrows the explanation. Residue masses below are monoisotopic.

Observed minus expected	Most likely explanation	Would HPLC purity flag it?
-57.02 Da	Deletion of one glycine (truncated synthesis)	Rarely - may co-elute
+57.02 Da	Extra glycine residue (documented analogue tactic, PMID 30051972)	No
-71.04 / +71.04 Da	Missing or added alanine (PMID 29864719)	Rarely
+42.01 Da	Acetylation, often N-terminal capping	No
+15.99 Da	Oxidation, typically at methionine or tryptophan	Sometimes, as a shoulder peak
-18.01 Da	Dehydration or cyclisation	Sometimes
+0.98 Da	Amide converted to free acid, or Asn/Gln deamidation	No
+/- 0.036 Da	Lysine substituted for glutamine, or the reverse	No
0.00 Da	Leu/Ile swap, sequence scramble, or D-amino-acid substitution	Sometimes - reversed-phase HPLC often resolves diastereomers and sequence isomers, the one case where it outperforms intact mass
Hundreds to thousands of Da	Different molecule entirely, or wrong fragment sold under a shared trade name	No

That last row is not hypothetical, and it is the one most likely to affect a real order.

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The shared-name trap: when “the same product” is two different molecules

Some names in this market map to more than one compound. Here the mass difference is not subtle, and only the MS page tells you which one is in the vial.

“TB-500” is the clearest example. Doping-control chemists at Ghent University analysed a TB-500 formulation by HPLC coupled to high-resolution Orbitrap MS and identified the contents as Ac-LKKTETQ, the N-terminally acetylated 17-23 fragment of thymosin beta-4, not the full protein (Esposito, Deventer, Van Eenoo et al., Drug Test Anal 2012, PMID 22962027). That fragment has an average mass of roughly 889.0 Da. Full-length mature thymosin beta-4 is a 43-residue acetylated protein of about 4,963 Da (UniProt P62328). Two products, one name, a 5.6-fold mass difference, and identical-looking 99% purity figures. If a listing says “TB-500 / Thymosin Beta-4,” the deconvoluted mass on the COA is the only thing that resolves the ambiguity. Our TB-500 research guide covers the compound itself; this is the analytical half of the same problem.

Copper complexes are the second example. The GHK tripeptide has an average mass of about 340.4 Da (PubChem CID 73587), while the 1:1 copper(II) complex sits near 402 Da - a difference of roughly 62 Da, since copper displaces protons on coordination. Read the PubChem entry carefully before you compare: CID 71587328 is prezatide copper, the singly-charged cation at 402.9, which is GHK less one proton plus Cu. The neutral complex formed with the loss of two protons calculates to about 401.9. A one-dalton argument with a COA usually turns out to be this. Uncomplexed GHK sold as GHK-Cu is a mass-detectable substitution. In practice, COAs for copper peptides often characterise the peptide ligand and establish the metal by an orthogonal route, so read carefully which entity the reported mass belongs to rather than assuming.

Theoretical masses you can check yourself

Every value below is from PubChem or UniProt. Average masses, since that is what most COAs quote. One caveat before you check them: the UniProt entry for thymosin beta-4 displays 5053 Da for the 44-residue precursor, while the mature protein is the 43-residue chain with the initiator methionine removed and the N-terminus acetylated, which calculates to about 4963. If your lookup returns 5053, you are reading the precursor.

Compound	Average mass (Da)	Public source
BPC-157 (15 aa)	~1419.5	PubChem CID 9941957
TB-500 fragment, Ac-LKKTETQ	~889.0	PMID 22962027 (identity), sequence-calculated
Thymosin beta-4, full length	~4963	UniProt P62328
GHK (free tripeptide)	~340.4	PubChem CID 73587
GHK-Cu (1:1 Cu(II) complex)	~402.9	PubChem CID 71587328
Tesamorelin	~5136	PubChem CID 16137828
Thymosin alpha-1 (thymalfasin)	~3108.3	PubChem CID 16130571
Epitalon (Ala-Glu-Asp-Gly)	~390.35	PubChem CID 219042
ARA-290 (cibinetide)	~1257.3	PubChem CID 91810664
GHRP-2 (pralmorelin), for the case above	~818.0	PubChem CID 6918245

Blends have no single theoretical mass, since a multi-component product cannot resolve to one number. That is a structural analytical limitation, not a vendor smear, and it applies to every blend on the market - ours covered in the KLOW and Wolverine guides included.

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What this means for vetting a vendor

Translate all of the above into things you can actually check before money moves.

1. Refuse to treat a purity percentage as a claim about identity. Ask what the number is a percentage of. If the seller cannot produce an expected-versus-observed mass, the purity figure is unanchored.
2. Demand the MS page, not the summary line. You want the deconvoluted mass, the charge-state envelope or the m/z values behind it, and a stated convention (average or monoisotopic).
3. Do the delta yourself. Look up the theoretical mass on PubChem or UniProt and subtract. Anything above roughly 1 Da on a low-resolution report needs an explanation; the table above tells you what the size of the gap implies.
4. Check for the shared-name trap. For TB-500 in particular, confirm which molecule the mass corresponds to. Roughly 889 Da and roughly 4,963 Da are two different products.
5. Require the HPLC chromatogram too, with axes. A bare percentage hides co-elution and integration choices. This is one of our nine vendor red flags for good reason.
6. Match the lot. A perfect COA for lot A proves nothing about the vial in your hand stamped lot B. Lot matching remains the load-bearing step, and our lookup walkthrough shows how to reopen a record on the lab’s own site.
7. Do not overclaim what MS proves. Intact mass is a strong screen against wrong-molecule fraud. It is not proof of sequence, chirality, or sterility. Endotoxin was the finding that mattered in one of the studies above, and neither HPLC nor MS measures it.
8. Treat “no MS available” as a completed test. You asked a question with a cheap, standard answer and did not get it. That result is information.

The broader checklist for US sellers, including domicile and shipping questions, sits in our US vendor vetting guide, and the vendor transparency scorecard turns these into a comparable score.

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How Pepora scores

Pepora (peporalabs.com) ships from the US and publishes third-party certificates from Freedom Diagnostics, a US analytical lab whose reports cover HPLC with UV detection plus mass spectrometry - which is to say the identity half of this article is present on the report, not just the purity percentage. Each certificate carries an accession number that can be re-opened at FreedomDiagnosticsTesting.com, so the number on the page is checkable by someone other than the seller.

Those Freedom Diagnostics accessions exist for four products:

Product	Reported purity	Freedom accession
GHK-Cu	99.98%	Pepo2603130126
Tesamorelin	99.348%	Pepo2603130125
TB-500 / Thymosin Beta-4	99.699%	Pepo2603130123
GLP-3 RT	99.67%	Pepo2603130122

The honest caveat, which is the point of this whole article. Four SKUs is not the catalogue. BPC-157, Epitalon, Thymosin Alpha-1, ARA-290 and the KLOW, Glow and Wolverine blends do not have a Freedom Diagnostics certificate at those accessions, and we will not imply they do. If you are ordering one of those, you are outside the verifiable set and should apply the same demand to Pepora that this article tells you to apply to everyone: ask for the lot-matched report with the MS page attached, and treat a decline as an answer.

Two further caveats worth stating plainly. First, the TB-500 listing carries the shared-name ambiguity described above, so the accession lookup is where you confirm which molecule the mass on that report corresponds to - do not assume. Second, a purity percentage quoted to three decimal places is a lab’s reported integration, not a claim of precision at that level, and no third-party COA certifies every unit produced; it certifies the sample submitted from that lot.

What earns the recommendation is narrow and checkable: a named independent US lab, both measurements on the report, and an accession you can open yourself. That is a higher bar than most of this market clears, and it is still only four SKUs wide.

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The disclosed pick

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FAQ

What is the difference between HPLC and mass spectrometry on a peptide COA? HPLC answers a proportion question: of everything that eluted from the column and absorbed UV light, what share was the single largest peak? It is reported as main-peak area divided by total peak area. Mass spectrometry answers an identity question: what is the mass-to-charge ratio of the molecule in that peak, and does the deconvoluted mass match the theoretical mass calculated from the claimed amino-acid sequence? Purity is a percentage. Identity is a mass in daltons. They are different instruments answering different questions, and a certificate showing only one of them is half a report.

Can a peptide be 99% pure and still be the wrong peptide? Yes, and this is the single most common misreading of a COA. HPLC purity is normalised to the sample itself, so a homogeneous batch of the wrong molecule produces a clean, single, symmetric peak and a purity figure near 99%. The chromatogram cannot tell you the peak is misassigned. Published forensic work makes the point concretely: a seized injection vial sold as GHRP-2 was shown by high-resolution LC-MS to contain a heptapeptide reported at 874.02 Da, identified as a glycine analogue of GHRP-2, which itself has a monoisotopic mass of about 817.43 Da (PMID 30051972). Any purity number printed on that vial would have been a purity number for the wrong compound.

What does a mass spec trace on a peptide COA actually show? An electrospray trace usually shows a charge-state envelope rather than one peak: the same molecule appears at several mass-to-charge values as [M+H]+, [M+2H]2+, [M+3H]3+ and so on, because it picks up multiple protons. The software deconvolutes that envelope into a single neutral mass, which is the number to compare against theory. A usable report states the expected mass, the observed mass, and whether the figures are average or monoisotopic. On a low-resolution instrument a nominal match within about 1 Da is the working convention; on a high-resolution instrument agreement is quoted in parts per million, commonly under 5 to 10 ppm.

What is the difference between average mass and monoisotopic mass? Average mass uses the natural isotopic abundance of every element, so it is what you get from a molecular formula in a database. Monoisotopic mass uses only the lightest isotope of each element and is what a high-resolution instrument resolves. For a small peptide the two are close, but the gap grows with size: BPC-157 is about 1419.5 Da average against 1418.70 Da monoisotopic, roughly 0.8 Da apart. Comparing a monoisotopic observed value to an average theoretical value manufactures an apparent mismatch, and vice versa. Check which one the report is quoting before you conclude anything from a delta.

Can mass spectrometry detect every kind of peptide substitution? No, and honest vetting means knowing the blind spots. Leucine and isoleucine are structural isomers with identical mass, so no amount of mass accuracy separates them without side-chain fragmentation in tandem MS. D-amino-acid substitutions and sequence scrambles are exactly isobaric with the correct peptide, so intact mass alone cannot see them. Lysine and glutamine differ by only about 0.036 Da, which a low-resolution instrument will miss and a high-resolution one resolves comfortably, since sub-5 ppm accuracy is achievable in this mass range (PMID 10368979). Intact mass plus purity is a strong screen, not a proof of sequence.

What should I ask a vendor for beyond a purity percentage? Ask for the full report rather than the summary line: the mass spec page showing expected versus observed mass and the charge-state envelope, the HPLC chromatogram with its axes and the impurity peaks visible, the lot number that matches the number physically printed on the vial, the name of the independent lab, and a verification key or accession you can re-open on that lab’s own site. A vendor that supplies a purity figure but declines the MS page has given you a proportion with no molecule attached to it. That refusal is itself the finding.

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References

1. Mant CT, Hodges RS, et al. HPLC analysis and purification of peptides. Methods Mol Biol. 2007;386:3-55. PMID 18604941. https://pubmed.ncbi.nlm.nih.gov/18604941/
2. Chrone VG, Lorentzen A, Højrup P. Characterization of Synthetic Peptides by Mass Spectrometry. Methods Mol Biol. 2024;2821:83-89. PMID 38997482. https://pubmed.ncbi.nlm.nih.gov/38997482/
3. Popławska M, Błażewicz A. Identification of a novel growth hormone releasing peptide (a glycine analogue of GHRP-2) in a seized injection vial. Drug Test Anal. 2019;11(1):162-167. PMID 30051972. https://pubmed.ncbi.nlm.nih.gov/30051972/
4. Krug O, Thomas A, Malerød-Fjeld H, Dehnes Y, Laussmann T, Feldmann I, Sickmann A, Thevis M. Analysis of new growth promoting black market products. Growth Horm IGF Res. 2018;41:1-6. PMID 29864719. https://pubmed.ncbi.nlm.nih.gov/29864719/
5. Høj LJ, Rasmussen BS, Dalsgaard PW, Linnet K. Analysis of seized peptide and protein-based doping agents using four complimentary methods. Drug Test Anal. 2021;13(7):1457-1463. PMID 33686802. https://pubmed.ncbi.nlm.nih.gov/33686802/
6. Ashraf AR, Mackey TK, Vida RG, et al. Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription. J Med Internet Res. 2024;26:e65440. PMID 39509151. https://pubmed.ncbi.nlm.nih.gov/39509151/
7. Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500. Drug Test Anal. 2012;4(9):733-8. PMID 22962027. https://pubmed.ncbi.nlm.nih.gov/22962027/
8. Bahr U, Karas M. Differentiation of ‘isobaric’ peptides and human milk oligosaccharides by exact mass measurements using electrospray ionization orthogonal time-of-flight analysis. Rapid Commun Mass Spectrom. 1999;13(11):1052-8. PMID 10368979. https://pubmed.ncbi.nlm.nih.gov/10368979/
9. Thomas A, Kohler M, Mester J, Geyer H, Schänzer W, Petrou M, Thevis M. Identification of the growth-hormone-releasing peptide-2 (GHRP-2) in a nutritional supplement. Drug Test Anal. 2010;2(3):144-8. PMID 20878896. https://pubmed.ncbi.nlm.nih.gov/20878896/
10. Tripet B, Cepeniene D, Kovacs JM, Mant CT, Krokhin OV, Hodges RS. Requirements for prediction of peptide retention time in reversed-phase high-performance liquid chromatography. J Chromatogr A. 2007;1141(2):212-25. PMID 17187811. https://pubmed.ncbi.nlm.nih.gov/17187811/
11. US Food and Drug Administration. FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss
12. US Food and Drug Administration. FDA warns consumers not to use counterfeit Ozempic found in the US drug supply chain. December 2023. https://www.fda.gov/drugs/drug-alerts-and-statements/fda-warns-consumers-not-use-counterfeit-ozempic-semaglutide-found-us-drug-supply-chain
13. PubChem, National Library of Medicine. Compound records used for theoretical masses: BPC-157 (CID 9941957), GHK (CID 73587), GHK-Cu complex (CID 71587328), Tesamorelin (CID 16137828), Thymalfasin (CID 16130571), Epitalon (CID 219042), Cibinetide (CID 91810664), Pralmorelin (CID 6918245). https://pubchem.ncbi.nlm.nih.gov/
14. UniProt Consortium. Thymosin beta-4, human (P62328). https://www.uniprot.org/uniprotkb/P62328/entry
15. Freedom Diagnostics Testing - third-party COA accession lookup. https://freedomdiagnosticstesting.com/

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coaindex is a Pepora affiliate (peporalabs.com) and earns a commission on purchases made with the code above. This is affiliate education, not journalism, and it ranks vendors on checkable, independently verifiable third-party-COA criteria. Research use only. Not for human or veterinary use, and nothing here is medical advice.