By Wholesale Lab Peptides · Published · Procurement guide
Compare like with like before accepting a match.
An LC-MS report may show an observed ion, a calculated value and a reconstructed molecular mass. These are related values, but they are not interchangeable. Before comparing numbers, identify what each column represents and which molecular identity the calculation assumes.
For BPC-157, Semax, Selank or TB-500, request the complete accepted identity behind the catalogue name. Keep stated modifications and molecular form with that specification. If the name remains unresolved, leave the identity review open rather than choosing a mass from another supplier. The bulk order specification guide defines the purchasing brief.
Observed m/z is different from neutral molecular mass.
Mass spectra report mass-to-charge ratio, written m/z. Electrospray can produce several charge states of a peptide. Deconvolution relates suitable ion signals to calculate the molecular mass of their originating component. Agilent explains spectral deconvolution.
Request the ion assignment and charge beside the observed value. A protonated ion or another stated adduct needs its own interpretation; the observed peak should not simply be read as the uncharged molecule. Agilent describes LC-MS ionisation and adducts. Ask the laboratory to reconcile the observed and calculated values on the same basis.
Keep the interpretation beside the number.
| Report field | Buyer review question |
|---|---|
| Expected material | Which exact sequence, modifications and stated molecular form were assessed? |
| Calculated value | What identity and mass-reporting convention generated it? |
| Observed ion | Is this m/z, with an identified charge and ion/adduct assignment? |
| Deconvoluted result | Which ion set and processing method support the reconstructed mass? |
| Comparison decision | What difference, units and acceptance criterion did the laboratory use? |
| Peak and method | Which chromatographic peak, spectrum, method and report revision apply? |
| Sample scope | How does the tested sample connect to the proposed supplied lot? |
Request explanations for missing assignments or inconsistent units. A purchasing reviewer should not invent a universal tolerance or reinterpret an unexplained spectrum as a pass.
Use the underlying spectrum and processing record.
Agilent published a peptide molecular-weight confirmation application with chromatograms, mass spectra and deconvolution output. Its example report identifies the ions used and shows component results. Read the primary application, especially PDF pages 3–5.
This illustrates why a cropped mass number is less informative than the connected report. It is background on an analytical workflow, not a report for our materials or an endorsement of this business.
Mass agreement is one part of identity review.
NIST researchers describe peptide identification using previously identified tandem mass spectra and spectral matching. That is a different evidential step from comparing one intact-mass value. Read NIST's peptide MS/MS identification research. Do not describe intact-mass agreement alone as complete sequence confirmation.
For TB-500, first resolve which material identity the supplier means. For a blend, ask which component signals were assigned; one reported match should not be extended to the entire composition. Identity evidence also does not establish chromatographic purity or measured content. Those distinctions belong in the separate purity and content guide.
Ask for the record needed for your proposed order.
Send the named material, accepted identity, quantities, vial or defined kit configuration and USA, Canada or Australia destination. Request available identity records, their sample-to-lot connection and the laboratory interpretation. Wholesale content and pack specifications are confirmed during enquiry.
The COA checklist covers the wider analytical document; batch traceability connects records to supply. One tested sample does not guarantee every unit or future lot. For private-label projects, keep material identity evidence separate from artwork approval.
Request identity documentationBrowse the wholesale catalogue or email sales@wholesalelabpeptides.com.