Peptide Guides
Important
TB-500 is not an approved medicine in any country. It holds no licence from the MHRA in the United Kingdom, the EMA in Europe, or the FDA in the United States. This guide explains product labelling and laboratory solution arithmetic. It is not medical advice, and nothing within it constitutes a recommendation to use TB-500. Products supplied through this site are intended for laboratory research use only.
Quick answer
- The number on a TB-500 vial is the nominal peptide content: the manufacturer's labelled claim of how much peptide the vial contains, not the total weight of the freeze-dried material.
- Content is not strength. The concentration of a laboratory solution depends on the amount of peptide and the volume of liquid it is dissolved in, written mg/ml.
- A vial labelled 5mg produces a nominally 5mg/ml solution with 1ml of laboratory diluent and a 2.5mg/ml solution with 2ml.
- For TB-500 the label weight carries an extra question most peptides do not have: which molecule the vial contains. Products under the name have been found to contain the fragment or full-length thymosin beta-4, and only an identity test settles it.
What the Number on a TB-500 Vial Means
The figure on a research peptide vial is the nominal peptide content: the manufacturer's labelled claim of how many milligrams of peptide the vial contains. A milligram, written mg, is one thousandth of a gram. The label figure is not the total weight of the freeze-dried material, which can include other ingredients from the drying process. It is also not a strength, not a concentration, and not a statement about purity or identity. For the compound itself, start with what TB-500 is.
The Vial Sizes TB-500 Is Sold In
Research suppliers commonly list TB-500 in 5mg and 10mg vials, and blended vials pairing it with BPC-157 are also sold with a stated weight for each peptide.
The size difference is quantity, not quality. A 10mg vial from the same batch as a 5mg vial contains the same powder in twice the amount. Which size suits a buyer comes down to how much material their work requires, how quickly it will be used, and price per milligram. Storage life belongs in that decision too, because reconstituted material has a shorter usable life than sealed powder; lyophilised peptide storage covers the detail.
Why 5mg and 10mg Are Amounts, Not Strengths
Strength only has meaning once the powder becomes a solution. A solution's strength is its concentration: how much peptide each millilitre of liquid contains, written mg/ml. Concentration is set by two numbers together. One is the nominal peptide content from the label. The other is the volume of liquid it is dissolved in, which the person preparing the solution chooses.
A 10mg vial is not a stronger product than a 5mg vial. It is a larger amount of the same product. Dissolved in enough liquid, 10mg produces a weaker solution than 5mg in very little liquid. The labelled content and the prepared concentration are different things, and confusing them is the most common misreading of peptide labels.
How TB-500 Solution Concentration Is Worked Out
Concentration is the amount of peptide divided by the volume of liquid. In laboratory preparation, a chosen volume of an appropriate laboratory diluent is added to the vial, and the concentration follows from the arithmetic; reconstituting peptides covers the process and the choice of diluent in full.
| Nominal peptide content | Laboratory diluent volume | Resulting nominal concentration |
|---|---|---|
| 5mg | 1ml | 5mg/ml |
| 5mg | 2ml | 2.5mg/ml |
| 10mg | 2ml | 5mg/ml |
There is no single correct volume to add. The choice depends on the concentration a piece of research work calls for, and the table exists so that whatever is chosen, the resulting concentration is known rather than guessed. Every figure is nominal, because it inherits the label's content claim.
The TB-500 Identity Question
For most research peptides the open question behind a label is purity. TB-500 adds a second one: identity. The name has not been used consistently in the research-product market, and published analyses of internet products sold as TB500 and TB1000 found contents that were not consistent with the products' own descriptions.2 The molecule the name originally described is a seven-amino-acid fragment of thymosin beta-4, a different molecule from the full 43-amino-acid peptide;1 TB-500 vs thymosin beta-4 explains the difference in full.
The arithmetic in this guide works identically for either molecule, because weight divided by volume is indifferent to chemistry. A batch-specific certificate of analysis with an identity test is the document that says which molecule the milligrams are.
Purity Is Not the Same as Peptide Content
An HPLC purity figure answers one question: of the peptide material detected in a sample, what proportion is the target peptide. It does not confirm that a vial labelled 5mg contains 5 milligrams. Mass spectrometry answers a different question: which molecule is present. It does not measure how much. Confirming the amount itself takes a quantitative content assay or a validated fill-control process. Purity, identity and content are three separate measurements, and a certificate of analysis can only vouch for the ones its tests actually cover. A "99% purity" figure is routinely misread as a statement about content, and it is not one.
TB-500 and BPC-157 Blend Vials
Blend vials contain two peptides in one vial, each with its own labelled content, and clear labelling states each figure separately rather than one combined number. The concentration arithmetic runs once per peptide. A vial labelled 5mg of each, dissolved in 2ml of diluent, gives a solution nominally 2.5mg/ml in each peptide. A combined 5mg/ml figure would describe the total powder and neither compound, because the two peptides are different substances. A blend also ties both compounds to one shared solution and one shared storage life. Two peptides supplied as separate vials, as in paired research bundles, keep their own solutions and storage lives, so this limitation applies to single mixed vials only.
Comparing Vial Sizes on Price per Milligram
Price per labelled milligram is the vial price divided by the nominal peptide content on the label. It compares vial sizes and suppliers on cost, and it stops there: it does not measure quality, and multiplying it by an HPLC purity percentage does not turn it into a content figure, because purity and content are different measurements. Larger vials usually cost less per labelled milligram, and that saving is only real if the material will be used while it remains in good condition.
For TB-500 the comparison has four parts: the price per labelled milligram, whether a dated certificate of analysis for the specific batch is published, which tests that certificate actually reports, and whether it confirms the identity of the molecule. A low price per milligram with no certificate is a number with nothing underneath it.
Common Questions About TB-500 Vials
What does 5mg mean on a TB-500 vial?
It is the nominal peptide content: the manufacturer's labelled claim that the vial contains 5 milligrams of peptide as freeze-dried powder. It is not a strength. The strength of any solution made from it depends on how much liquid the powder is dissolved in.
How much bacteriostatic water goes into a TB-500 vial?
There is no single correct volume. The volume of diluent chosen sets the concentration of the resulting laboratory solution, and the table above shows the arithmetic. With 1ml a vial labelled 5mg gives a nominally 5mg/ml solution, with 2ml it gives 2.5mg/ml, and the full method is in reconstituting peptides.
Is a 10mg vial of TB-500 stronger than a 5mg vial?
No. It contains twice the labelled amount of the same material. Strength belongs to solutions, and a solution's strength is set by the amount of peptide and the volume of liquid together.
Does the arithmetic change if a vial contains full-length thymosin beta-4?
The arithmetic is the same: amount divided by volume. What changes is which molecule the solution contains, which is why an identity-tested certificate matters more for TB-500 than for most research peptides.
TB-500 Research Specification
We supply TB-500 as freeze-dried (lyophilised) powder in sealed 5mg and 10mg vials labelled by nominal peptide content. Each batch is purity-tested by HPLC and identity-confirmed by mass spectrometry, and the dated certificate of analysis states what each test measured. The current TB-500 batch and certificate of analysis is listed with its documentation.
Supplied for laboratory research use only. Not for human consumption.
References
- 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, a product suspected to possess doping potential. Drug Test Anal. 2012;4(9):733-8. DOI
- Delcourt V, Garcia P, Chabot B, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023;15(4):458-464. DOI