A heavy peptide specification may contain several percentages. They can look interchangeable, but they answer different questions. Isotope enrichment describes the labelled atoms; chemical purity describes the composition of the material under a stated analytical method.
A real catalogue example shows the difference
Sigma-Aldrich’s catalogue entry for L-lysine-13C6,15N2 hydrochloride lists 99 atom % carbon-13 and 99 atom % nitrogen-15, alongside an assay of 95% (CP). This is a labelled amino-acid building block, not a finished peptide. Its separate specification fields make the distinction visible: high isotope enrichment is not a statement that the whole material has the same chemical purity.
What should be specified for a finished heavy peptide?
Record which residue carries the label and exactly which atoms are substituted. Then state the chemical-purity requirement separately. For quantitative work, also ask how the peptide amount or concentration is assigned. A labelled sequence, an isotope-enrichment figure and an HPLC purity result do not automatically establish an accurate amount for an internal standard.
Why light material may matter
A heavy standard is often used alongside an unlabelled target. If light material is present in the standard, it can affect the light-channel measurement. Whether this matters depends on the assay range and analytical workflow. Ask about the relevant light contamination assessment rather than assuming an isotope-enrichment percentage rules out every interference.
Keep the comparison like for like
When comparing quotations, use the same sequence, labelled position, terminal form, purity method and amount-assignment basis. Ask which results are measured on the finished peptide and which describe starting materials. The catalogue numbers above explain the terminology; they do not certify NHD material or establish a universal acceptance limit.
Next step with NHD
The related product cards below identify catalogue peptide families. They do not confirm availability of biotinylated, fluorescent, isotope-labelled or library versions. For a modified material, specify the exact design in a custom inquiry.
Start with the Heavy peptide ordering guide. For a quotation, send NHD your sequence or product name, quantity and required documents. Confirm the exact form, feasibility, available testing and delivery terms before ordering.
Sources
Public references explain the topic; they are not NHD batch evidence. Research materials are for laboratory research, development and manufacturing, not human or veterinary use.
Sources & editorial method
AI-assisted writing, source checks and illustrated cover.
2 linked records are listed in the references below. Read the editorial and AI-assistance policy.
How to interpret this article
Public data and labeled teaching calculations; not NHD batch results. Confirm project and document availability.
Research-use boundary: Catalog materials discussed on this website are for laboratory research, development and manufacturing use only, not for human or veterinary use. This content is not medical advice and does not provide administration instructions.
Primary records and authoritative sources
- Sigma-Aldrich: separate enrichment and assay fieldsPublic reference, not NHD batch evidence.
- JPT: isotope-labelled peptidesPublic reference, not NHD batch evidence.
Continue with structured records
Move from this editorial analysis to the product identity, filtered evidence and controlled terminology behind it.
