About This Peptide FAQ
This FAQ collects the questions researchers ask us most about peptide science, analytical testing, documentation, Vinnix products and orders. They're grouped into five sections, and every answer links to the page that covers it in full.
Don't see your question in this FAQ? Email [email protected] or use the contact form.
Peptide Fundamentals
What are peptides?
Peptides are chains of amino acids linked by peptide bonds. What makes one peptide different from another is the order of those amino acids, its sequence, so two chains of identical length can be completely different compounds. Sizes run from two residues up to several dozen. For a fuller introduction than this FAQ can give, see what are peptides.
What are amino acids?
Amino acids are organic compounds in which an amino group, a carboxyl group and a side chain all hang off a central carbon. That side chain is what gives each one its own chemistry. They're the building blocks of peptides and proteins, and synthetic research peptides sometimes include non-standard or D-configured residues as well. The amino acids page has more.
What is a peptide bond?
It's the amide linkage joining the carboxyl group of one amino acid to the amino group of the next. The bond forms in a condensation reaction that gives off one molecule of water, and repeating it over and over builds the peptide backbone. Our article on peptide bonds covers its structure and why it's rigid and planar.
What is a peptide sequence?
It's the list of a chain's amino acids in order, from the N-terminus to the C-terminus. You'll see it in one-letter codes such as GEPPPGKPADDAGLV or three-letter codes such as Gly-Glu-Pro. No identifier matters more for a peptide. Vinnix compound pages show verified sequences, and the peptide sequences guide explains the notation.
What are polypeptides?
A polypeptide is a longer, unbranched chain of amino acids joined by peptide bonds. People usually reserve the word for chains longer than about ten to twenty residues, though no single cutoff is fixed. Since a protein can be one polypeptide chain or several folded together, the two terms overlap a lot in scientific writing.
How are peptides different from proteins?
Both are chains of amino acids. Peptides tend to be shorter, while proteins are larger chains that fold into stable three-dimensional structures, sometimes with several chains working together. Where one ends and the other begins is a matter of convention, not a fixed residue count. Our article on peptides vs proteins compares them in detail.
Testing
What is HPLC?
HPLC is a liquid chromatography technique. It pumps a dissolved sample through a packed column at high pressure, and the components separate according to how they interact with the column. A detector records each one as a peak over time. With peptides, purity is reported as the main peak's share of the total peak area. See HPLC testing.
What is mass spectrometry?
Mass spectrometry turns molecules into ions and measures them by mass-to-charge ratio. For a peptide, you compare the observed mass with the mass expected from its molecular formula, and a match supports identity. Larger peptides often show up at several charge states. Our article on mass spectrometry explains how to read a spectrum.
What is LC-MS?
LC-MS couples liquid chromatography to mass spectrometry. The chromatography separates a sample's components and feeds each one straight into the mass spectrometer, so you learn how many components there are and what each one weighs. Labs use it widely to identify a peptide and its impurities in a single run. See what is LC-MS.
What does purity mean?
Purity tells you how much of a tested sample is the intended compound, relative to the other components detected. With peptides it's usually an HPLC area percentage at a stated wavelength. It doesn't measure identity, and it isn't the same as net peptide content, which also accounts for water and counter-ions. Read peptide purity explained.
What is a chromatogram?
It's the graph an HPLC system produces, with detector signal on the vertical axis and retention time on the horizontal axis. Every separated component shows up as a peak. Where a peak sits reflects how long that component took to pass through the column, and the area under it is used to work out its share of the sample.
Documentation
What is a COA?
A COA, short for certificate of analysis, reports analytical results for a specific sample or batch. A useful one names the product, batch number, testing laboratory, test date and methods, and gives the reported values, such as HPLC purity and observed mass. See what is a certificate of analysis and our guide on how to read a COA.
What is a batch number?
A batch number identifies a quantity of material made in one run under the same conditions. It ties the physical product to the production records and analytical reports for that run. So when you check documentation, the batch number on the report should match the one supplied with your product.
What is a lot number?
A lot number identifies a defined quantity of product that's tracked together through packaging and distribution, usually one batch or a uniform portion of one. On labels and certificates, batch and lot are often used interchangeably. Either way, what counts is that the identifier on the report matches the one on your product.
Does one COA apply to every batch?
No. A certificate of analysis covers only the batch that was sampled and tested. Each production run can differ, so a new batch needs its own report, even for the same product and strength. Vinnix links every report to one batch, and a new batch has no documentation link until its own report is published.
Where is Vinnix documentation?
Each product page will link to its batch documentation, and reports will be collected in the Vinnix COA Library as they're published, searchable by product, SKU or batch number. A record lists the compound, batch, testing laboratory, test date and available reports. Our quality and documentation page explains how it's all organized.
Products
Where are product specifications?
On each product page: compound name, SKU, quantity and, for blends, the components. Compound identifiers such as sequence, molecular formula, molecular weight and CAS number live on the compound profile, verified against PubChem. If Vinnix hasn't confirmed a value yet, for example storage information for a new product, it's left off until the batch record is published.
How do I locate a compound?
Start with the Vinnix Compound Library, an A to Z directory of every compound we supply or profile. Each entry links to a profile with identity data and research background, plus any Vinnix product containing that compound. Prefer to browse by product? Head to the research peptide catalog.
How do I locate a batch?
Take the batch or lot identifier that came with your product and search for it in the Vinnix COA Library. You can also open the product page and follow its documentation link. Make sure the batch number on the report matches yours exactly. If there's no report for your batch, email [email protected] with the product name, SKU and batch number.
Where can I find related research information?
Each compound profile summarizes the published research, with PubMed references labeled by study type and links to related articles. For background reading beyond this FAQ, the Vinnix Research Library covers peptide fundamentals and analytical testing, and the peptide glossary defines common terms. Our research methodology explains how sources are chosen.
Are Vinnix products for human use?
No. Vinnix products are supplied for laboratory research use only. They aren't intended for human or veterinary use, diagnosis or any clinical application, and we don't provide instructions for use. Our product pages cover compound identity, specifications and documentation, nothing more. You'll find the full terms in the product and research disclosure.
How should products be stored?
It depends on the compound and the product format, so go by the storage information for that specific product rather than a single rule for every peptide or amino acid. If a product's storage information hasn't been published yet, it will appear with the batch record. Peptide storage covers the general principles. Email [email protected] if you need it before it's posted.
Orders
How do I contact support?
If this FAQ doesn't cover your question, email [email protected] or use the form on the contact page, picking Product Information, Order Support, Documentation or General Inquiries as the inquiry type. Order questions should include your order number. Documentation questions should include the product name, SKU and batch number, which lets us match your request to the right records.
How do I locate an order?
Your order number is in the order confirmation sent to the email address you used at checkout, and shipping updates go to that same address. Can't find an order or its status? Email [email protected] with your name, the checkout email and the order number if you have it, and the support team will look it up.
How is tracking provided?
If tracking is available, we email it once the shipment has been prepared, to the address you gave at checkout. Carrier tracking sometimes takes a while to update after a label is created. If an order looks lost or arrives damaged, contact support with your order number. The shipping policy has the details.
What is the return policy?
If something's wrong with an order, email [email protected] with your order number before returning anything, and please don't send a product back without return instructions. Report an incorrect or damaged shipment promptly, with photographs. Handling conditions matter for these products, so not every product is eligible for return. See the return and refund policy.
Do you ship nationwide?
Checkout shows shipping availability, restrictions and delivery options, and the Vinnix shipping policy sets them out in full. We process orders according to product availability, and processing time is separate from carrier transit time. If you're unsure about a particular destination, email [email protected] before you order.