Four cosmetic peptides on one catalogue state their recommended use level in two units, over a span of four orders of magnitude. That is not a mistake in the sheets; it is what happens when use level is quoted per application instead of per substance, and it is the number most likely to be copied wrongly into a brief. Nonapeptide-1, Hexapeptide-2, Decapeptide-12 and Dipeptide-1 are used below as the worked examples.
1. One Catalogue, Two Units, Four Different Ranges
The four sheets do not share a convention. Two quote percent, one quotes ppm, and one gives a window wide enough to cover both. Reading a use level without the unit attached is the first way a formula goes wrong.
| Product | CAS | Use level on our sheet | Stated as | What it resolves to |
| Nonapeptide-1 | 158563-45-2 | 5 to 5,000 ppm | ppm, active peptide | 0.0005% to 0.5% |
| Hexapeptide-2 | 87616-84-0 | 0.01% to 5.0% | percent | 100 ppm to 50,000 ppm |
| Decapeptide-12 | 137665-91-9 | 2% to 5% | percent, final product | 20,000 ppm to 50,000 ppm |
| Dipeptide-1 | 70904-56-2 | 0.05% to 0.5% | percent | 500 ppm to 5,000 ppm |
Read down the last column. The lowest figure on the catalogue is 5 ppm and the highest is 50,000 ppm, and both are correct for the product they belong to. A single use level carried across all four would be wrong by a factor of ten to a thousand.
2. 5,000 ppm Is 0.5%, And That Conversion Is The Whole Job
The arithmetic is not difficult, which is exactly why it gets skipped. One percent is 10,000 ppm, so a use level of 5,000 ppm is 0.5% and a level of 100 ppm is 0.01%.
Put that against the table and the error becomes visible. Nonapeptide-1 at its top end of 5,000 ppm is 0.5%, which is the bottom of Hexapeptide-2's range and a quarter of Decapeptide-12's. A formulator who reads three sheets as though they all meant ppm would use Decapeptide-12 at 200 ppm where the sheet asks for 2%, a hundredfold short.
The mistake is not careless; the sheets invite it. Percent appears without a space before the sign on some lines, ppm appears with a comma separator on others, and en dashes separate the ends of ranges. Convert every figure to one unit in your own brief before comparing anything.
3. Active Peptide Is Not The Powder On The Scale
The Nonapeptide-1 sheet is explicit in a way the others are not: its figures are ppm of active peptide. That distinction decides the weigh-out, because the powder is not entirely peptide.
Our grades are offered at 95% and 98% by HPLC for Nonapeptide-1, Hexapeptide-2 and Dipeptide-1, and Decapeptide-12 is quoted at 99%. The balance is water, counter-ion and synthesis residuals. At 98% the correction is small enough to ignore in most briefs; at 95% it is a five percent correction, and it compounds with any overage you add for shelf life.
Ask which basis the number is on before you accept it: active peptide, or material as supplied. Two suppliers quoting 200 ppm can be quoting different masses.
4. A Range Of 0.01% To 5.0% Is Not A Use Level
Hexapeptide-2's window spans five hundredfold, and Nonapeptide-1's spans a thousandfold. Those ranges are honest, because the right figure depends on the format, but they do not tell a buyer what to put in the formula.
Three constraints narrow them. The format sets the ceiling: a serum tolerates what a cream may not, and Nonapeptide-1's sheet already breaks its own range down by application, with brightening serums and essences at 100 to 5,000 ppm. The solubility limit sets the floor in practice. And the cost of the peptide per tonne sets the working band long before either limit binds.
5. What The Use Level Costs Per Tonne
Mass is the part of the decision that can be settled before any price is quoted, and it is where the unit error becomes expensive.
| Use level | Peptide per 1,000 kg | Where that sits on the catalogue |
| 100 ppm | 100 g | Bottom of Nonapeptide-1's serum band |
| 0.5% | 5 kg | Top of Nonapeptide-1, bottom of Hexapeptide-2 |
| 2% | 20 kg | Bottom of Decapeptide-12's range |
| 5% | 50 kg | Top of both percent ranges |
A tonne of serum at 100 ppm carries 100 grams of peptide. The same tonne at 5% carries 50 kilograms, five hundred times as much. That is the figure to put beside the quoted price per kilogram, because it is the one that decides whether the formula can be sold at the intended retail price.
6. Identity Comes Before Dose: One CAS, Two Formulas
A use level is only meaningful for a verified substance, and here the catalogue does not resolve cleanly. PubChem returns C65H90N18O17 and a molecular weight of 1395.5 for CAS 137665-91-9, while our own Decapeptide-12 sheet states C45H74N14O12S2 and a molecular weight of 1083.
Both cannot describe the same molecule. The formula on the certificate, the sequence and the mass spectrometry trace have to agree before a use level is applied to a batch, and this is the one line on the four sheets that a buyer should query rather than accept. For the other three the identifiers reconcile: 70904-56-2 gives C15H23N5O4 at 337.37, 87616-84-0 gives C46H56N12O6 at 873.0, and 158563-45-2 gives C61H87N15O9S at 1206.5. Where the identity does not reconcile, ask for the sequence and the mass spectrometry trace before ordering, because a formula printed on a certificate is not evidence that the batch matches the CAS number on the drum.
7. Dipeptide-1 Is Not Acetyl Dipeptide-1 Cetyl Ester
Two names separated by three words belong to different substances with different functions, and the use levels differ by the same order as everything else here.
Dipeptide-1 is CAS 70904-56-2, a Tyr-Arg dipeptide that our sheet lists for anti-wrinkle and firming work at 0.05% to 0.5%, water-soluble and stored long term at minus 15 to minus 20 degrees. Acetyl Dipeptide-1 Cetyl Ester is CAS 196604-48-5, a different molecule with a C16 tail, listed for soothing and firming. Quoting one against the other's specification produces a formula that assays correctly and does nothing.
| Product | CAS | Sequence or structural feature | What our sheet lists it for | Use level reference |
| Dipeptide-1 | 70904-56-2 | Tyr-Arg | Anti-wrinkle and firming | 0.05% to 0.5% on its own sheet |
| Acetyl Dipeptide-1 Cetyl Ester | 196604-48-5 | Acetylated dipeptide carrying a cetyl ester | Soothing and firming | A separate figure on a separate sheet |
8. What To Write On The Purchase Order
Five lines remove most of the ambiguity described above, and each one answers a question the certificate cannot answer on its own.
› CAS number and peptide name together, so a synonym cannot substitute for identity
› Use level stated in one unit, converted by you, not by the supplier
› Whether the level refers to active peptide or material as supplied
› Assay with the method named, HPLC or HPLC plus mass spectrometry
› The application format the level was set for, since that is what narrows a range
None of this is a claim about what any peptide does. A use level describes how much material goes into a batch; the wording on the pack is a separate decision governed by cosmetic labelling rules, and the level does not license the sentence.
Frequently Asked Questions
Q: How Do I Convert Ppm To Percent For A Peptide Use Level?
A: Divide by 10,000. One percent is 10,000 ppm, so 5,000 ppm is 0.5%, 500 ppm is 0.05%, 100 ppm is 0.01% and 5 ppm is 0.0005%. Convert every figure on every sheet into one unit before comparing them, because percent and ppm appear side by side on this catalogue and the difference is two orders of magnitude.
Q: Why Do The Four Peptides Have Such Different Use Levels?
A: Because the level is set per application, not per substance. A peptide used at 100 ppm in a serum and one used at 5% in a spot product are answering different formulation questions. The ranges also reflect what each application can tolerate in cost and in solubility, which is why a single number cannot cover a catalogue.
Q: What Does Active Peptide Mean On A Specification Sheet?
A: It means the percentage refers to the peptide itself rather than to the powder weighed out. At 98% assay the difference is two percent of the weigh-out; at 95% it is five percent. Ask which basis a supplier is quoting, because two offers at the same ppm can refer to different masses of material.
Q: Which Use Level Should I Choose Inside A Published Range?
A: Start from the format. A clear aqueous serum and a cream tolerate different levels, and some sheets already break the range down by application, as ours does for Nonapeptide-1 at 100 to 5,000 ppm in serums and essences. Then check solubility and cost per tonne, and confirm with a stability trial before a batch is committed.
Q: Can I Use One Peptide's Level For Another Peptide?
A: No. The levels here span 5 ppm to 50,000 ppm depending on the product, and the sheets state them in different units. Carrying a figure from one product to another can leave a formula a hundredfold short or fifty times over, and neither error shows up until the batch is made.
Q: Does A Higher Use Level Support A Stronger Claim?
A: No. The use level describes what goes into the batch; the claim describes what the product may say, and the two are governed separately. Under Regulation (EC) No 1223/2009 a cosmetic is defined by its intended function of altering appearance, and claim wording has to be substantiated on its own evidence, whatever the formula contains.
Xi'an Huilin Bio-tech Co., Ltd. supplies Nonapeptide-1, Hexapeptide-2, Decapeptide-12 and Dipeptide-1 as cosmetic raw materials, each with a specification sheet stating the use level and its basis.
Sources
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1. Regulation (EC) No 1223/2009 on cosmetic products, EUR-Lex. https://eur-lex.europa.eu/eli/reg/2009/1223/oj
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2. Nonapeptide-1, CAS 158563-45-2, CID 10418849. PubChem, U.S. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/10418849
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3. Hexapeptide-2, CAS 87616-84-0, CID 9919153. PubChem, U.S. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/9919153
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4. Decapeptide-12, CAS 137665-91-9, CID 25087629. PubChem, U.S. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/25087629
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5. Dipeptide-1, CAS 70904-56-2, CID 123804. PubChem, U.S. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/123804