1. The first refusal is not a number — it is an unnamed carton
If the batch sheet already has a percent and the incoming peptide aisle is still a nickname, delete the percent. A storefront listing, a WhatsApp photo, or last month’s memory is not a weighing object. Write the commercial name, the pack size in front of you, and the lot code that actually arrived. Until those three exist, dosage math is fan fiction.
2. Three weighing objects, not one word ‘peptide’
A neat powder — a kilogram-scale GHK-Cu copper peptide is the usual example — is a solid whose file, if it exists, talks about that powder or named salt. A standardized supplier concentrate — a SNAP-8 concentrate or a small Argireline liquid — is a purchased liquid whose peptide fraction and solvents live on that SKU’s sheet. A workshop dilution is a third object you created; it inherits neither the powder assay nor the concentrate’s stated fraction unless you wrote the dilution yourself and kept the retain. Do not paste a number from object one onto object two because both boxes say peptide.
3. Name the active basis before you name a percent
As-is commercial mass is how much of the purchased object you will weigh. Peptide-solids basis is the fraction that file assigns to the sequence. Salt basis and copper-ion basis are different counters; they are common on copper complexes and almost never interchangeable with ‘% peptide’ in a brief. If two people in the room are using two bases, you do not have a disagreement about dose. You have two recipes. An Argireline liquid counted as-is is not the same arithmetic as that liquid counted on peptide solids.
4. Bind this lot’s file — not last year’s PDF and not the invoice nickname
TDS language can change between lots. A COA is a statement about the lot that was tested, not a licence to reuse last spring’s factor. The invoice description can be shorter than the legal name. Eyeseryl Solution B is a useful warning here: the word Solution is part of a commercial form, not a hint that you may invent a solids number. If this carton has no file, you do not have a factor. You have a purchasing hold.
5. What this gate is not
It is not the page that says INCI order and a marketed finished percent are not an HPLC assay. That job is already written. It is not the pre-batch compatibility matrix for a crowded stack. It is not a lesson in reconstituting a powder with the wrong water or hold time. Those are later doors. This door only asks: do you know which object you will weigh, which lot document defines it, and which basis the percent will use?
6. Only then open the calculator — and only for that object
Write four lines: object class, lot code, bound file date, active basis. Then, and only then, convert the brief into a mass of that commercial material. Read late-addition notes for leave-on peptides for stage and temperature after identity is closed, not instead of it. If the brief changes SKU mid-week, the four lines reopen. A new carton is a new object even when the trade name matches.