Reading Product Specifications
Every product page carries a spec block. Learn to decode it — vial mass, sequence, molecular formula, molecular weight, CAS number and storage — so you know exactly what you are ordering.
A product specification block looks technical, but each field answers a specific, useful question about what is in the vial. Learning to read it means you order with full understanding rather than trusting a product name alone — and it makes comparing products and cross-checking a Certificate of Analysis much easier.
This guide walks the fields you will commonly see on a research-peptide product page and explains what each one tells you and why it matters. It complements the purity and certificate-of-analysis guides, which go deeper on testing.
Research use only.
WHAT YOU NEED
Tools
- A product page or spec sheet
STEP-BY-STEP
Vial mass (mg) — how much is in the vial
The milligram figure is the total peptide mass per vial — the number you enter first into the reconstitution calculator. It, together with your chosen water volume, sets the concentration of everything you draw.
Tip: This is the number you carry straight into the calculator to plan concentration.
Peptide sequence — the identity in shorthand
Many spec sheets list the amino-acid sequence (often in single-letter or three-letter code). It is the peptide's precise identity — the exact chain of amino acids — and is what analytical testing ultimately confirms.
Molecular formula and molecular weight
The molecular formula lists the atoms in one molecule; the molecular weight (in daltons) is their combined mass. Molecular weight is the value mass spectrometry measures on a CoA to confirm the compound's identity — so it is a useful cross-check.
CAS number — the registry identifier
A CAS number is a unique registry identifier for a chemical substance. Where listed, it lets you unambiguously identify the exact compound independent of any brand or trade name.
Purity specification
The spec usually states a minimum purity, commonly ≥98% by HPLC. Treat this as the manufacturing target, confirmed for your specific vial by the batch Certificate of Analysis. See the purity guide for what the figure means.
Storage and handling notes
Look for the recommended storage state — lyophilised vials cold and dry, reconstituted solutions refrigerated. Any compound-specific handling note on the spec sheet takes precedence over the general defaults.
Using the spec sheet to cross-check a CoA
The spec sheet and the Certificate of Analysis are meant to agree. The compound name and molecular weight on the spec should match the identity and mass confirmed by mass spectrometry on the CoA; the purity specification (e.g. ≥98%) should be met or exceeded by the batch's measured HPLC purity.
Reading the two together is a simple, powerful check: the spec sheet says what the product should be, and the batch CoA is the evidence that your specific vial meets it. When the two line up on identity, mass and purity, you have strong confidence in what you are working with.
PUT IT INTO PRACTICE
FREQUENTLY ASKED
What does the mg figure on a peptide product mean?
It is the total peptide mass in the vial — for example a 10 mg vial. This is the first number you enter into the reconstitution calculator; combined with your chosen water volume, it sets the concentration of every draw.
What is a CAS number?
A CAS number is a unique registry identifier for a chemical substance. Where a spec sheet lists one, it lets you identify the exact compound unambiguously, independent of any brand or trade name.
What is the difference between molecular formula and molecular weight?
The molecular formula lists the atoms in one molecule of the compound; the molecular weight (in daltons) is their combined mass. Molecular weight is what mass spectrometry measures on a Certificate of Analysis to confirm identity.
How do I use the spec sheet with the Certificate of Analysis?
Cross-check them: the compound name and molecular weight should match the CoA's mass-spec identity, and the measured HPLC purity should meet or exceed the spec's minimum. The spec says what the product should be; the CoA is evidence your vial meets it.