# What the numbers on your peptide CoA actually mean - facts

Canonical page: https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean
Type: Lab article

## TL;DR

A peptide CoA's two key values are HPLC purity (target peak area / all peaks x 100) and mass spec identity (observed m/z vs theoretical mass). How to read them.

## Facts Index

| Fact ID | Category | Entity | Attribute | Value | Source | Evidence |
|---|---|---|---|---|---|---|
| what-the-numbers-on-your-peptide-coa-actually-mean:title | identity | What the numbers on your peptide CoA actually mean | title | What the numbers on your peptide CoA actually mean | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:published | identity | What the numbers on your peptide CoA actually mean | published | 2026-08-06 | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:author | identity | What the numbers on your peptide CoA actually mean | author | Preppin' Peppers Editorial Team | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:topics | identity | What the numbers on your peptide CoA actually mean | topics | Education, guide, peptide education | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:summary | content | What the numbers on your peptide CoA actually mean | summary | A peptide CoA's two key values are HPLC purity (target peak area / all peaks x 100) and mass spec identity (observed m/z vs theoretical mass). How to read them. | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:section-1 | content | What the numbers on your peptide CoA actually mean | section | What a peptide CoA is | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:section-2 | content | What the numbers on your peptide CoA actually mean | section | What the HPLC Purity Number Actually Tells You | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:section-3 | content | What the numbers on your peptide CoA actually mean | section | Reading the Mass Spectrometry Data | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:section-4 | content | What the numbers on your peptide CoA actually mean | section | What a Complete CoA Should Always Include | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:section-5 | content | What the numbers on your peptide CoA actually mean | section | Common Mistakes Researchers Make with CoAs | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:section-7 | content | What the numbers on your peptide CoA actually mean | section | What the research community gets wrong about reading a CoA | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean |
| what-the-numbers-on-your-peptide-coa-actually-mean:product-gansulin-metal-peptide-pen | products | What the numbers on your peptide CoA actually mean | references product | Gansulin Pen · Reusable Click-Dial, 3 ml (1-60 Units) | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/products/gansulin-metal-peptide-pen |
| what-the-numbers-on-your-peptide-coa-actually-mean:product-gansulin-3ml-cartridge | products | What the numbers on your peptide CoA actually mean | references product | Gansulin-Compatible 3 ml Glass Cartridge for Pens (10-Pack) | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.preppinpeppers.com/products/gansulin-3ml-cartridge |
| what-the-numbers-on-your-peptide-coa-actually-mean:source-www-bachem-com | source | What the numbers on your peptide CoA actually mean | cites | Bachem , Quality Control of Amino Acids and Peptides: A Guide (HPLC purity, MS identity, net peptide content, counterions, Karl Fischer water) - www.bachem.com | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.bachem.com/knowledge-center/quality-control-of-amino-acids-peptides-a-guide/ |
| what-the-numbers-on-your-peptide-coa-actually-mean:source-www-ambiopharm-com | source | What the numbers on your peptide CoA actually mean | cites | AmbioPharm , What Is Net Peptide Content? (net peptide content vs purity, acetate/TFA salt forms) - www.ambiopharm.com | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://www.ambiopharm.com/faq/what-is-net-peptide-content/ |
| what-the-numbers-on-your-peptide-coa-actually-mean:source-altabioscience-com | source | What the numbers on your peptide CoA actually mean | cites | AltaBioscience , Peptide Synthesis, Purification and Product Analysis (RP-HPLC purity at 215 nm, MALDI-TOF MS identity, amino acid analysis) - altabioscience.com | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://altabioscience.com/articles/peptide-synthesis-purification-and-product-analysis/ |
| what-the-numbers-on-your-peptide-coa-actually-mean:source-pubmed-ncbi-nlm-nih-gov | source | What the numbers on your peptide CoA actually mean | cites | D'Hondt et al., J Pharm Biomed Anal 2014: Related impurities in peptide medicines - pubmed.ncbi.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://pubmed.ncbi.nlm.nih.gov/25044089/ |
| what-the-numbers-on-your-peptide-coa-actually-mean:source-pmc-ncbi-nlm-nih-gov | source | What the numbers on your peptide CoA actually mean | cites | Thacker et al., Front Immunol 2022: Detection of innate immune response modulating impurities (IIRMI) in therapeutic peptides and proteins: Impact of excipients - pmc.ncbi.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://pmc.ncbi.nlm.nih.gov/articles/PMC9485840/ |
| what-the-numbers-on-your-peptide-coa-actually-mean:source-pubmed-ncbi-nlm-nih-gov-2 | source | What the numbers on your peptide CoA actually mean | cites | Badgujar et al., Chirality 2024: Enantiomeric purity of synthetic therapeutic peptides: A review - pubmed.ncbi.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/what-the-numbers-on-your-peptide-coa-actually-mean) | https://pubmed.ncbi.nlm.nih.gov/38448043/ |

## FAQ

### What does the HPLC purity percentage on a peptide certificate of analysis actually measure?

It is the target compound's UV peak area divided by the total area of all peaks, multiplied by 100. It quantifies relative purity of light-absorbing material but cannot confirm the main peak is the correct molecule.

### How do I verify the mass spec data on a peptide CoA?

Multiply each observed m/z by its charge state, then subtract ~1.008 Da per proton added. The resulting neutral mass should fall within ~0.5 Da of the theoretical molecular weight listed on the CoA.

### What HPLC purity level is considered acceptable for peptide research?

≥95% is the general minimum for most bench work; ≥98% is preferred for low-concentration experiments where trace impurities represent a proportionally larger fraction of the added material.

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