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Peptide COA Interpretation Quick Reference 2026 | Artemis Labs

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COA Interpretation Quick Reference

One-Page Guide to Understanding Certificate of Analysis Data

Printable field-by-field reference for reading a research peptide Certificate of Analysis (COA). Match-then-trust: verify the batch number on the COA against the vial before opening. Research use only.

Research Highlights (May 2026 update)

  • Six fields define a real COA: identity (MS), purity (HPLC ≥99% target), water content (Karl Fischer), endotoxin (for in vivo work), batch / lot number matching the vial, and named third-party lab with credentials.
  • Three immediate red flags: missing batch number, undated testing, or generic “professional testing” without a named lab — any one makes the COA insufficient.
  • Match-then-trust: A 99% purity number means nothing if the batch number doesn’t match your vial.

For research-use only. Not for human consumption. These statements have not been evaluated by the FDA. Last updated: May 20, 2026.

What is a COA?

A Certificate of Analysis (COA) is the quality documentation for a research compound batch. It shows test results proving the compound meets specifications. Every batch should have its own unique COA.

This quick reference explains what each COA section means and what to look for.

COA Sections Explained

IDENTITY (Structural Confirmation)

What it shows: Proves the compound is actually what the label claims.

How it’s tested:
– Mass Spectrometry (MS): Shows molecular weight and fragmentation pattern
– NMR or HPLC-MS: Confirms molecular structure

What GOOD looks like:
– [ ] Molecular weight matches expected value (e.g., Tirzepatide = 5,097.6 Da)
– [ ] MS peaks align with known structure
– [ ] Result clearly states “PASS” or shows >95% match
– [ ] Lab certifies the compound identity

Red Flags:
– Missing MS data or molecular weight
– Molecular weight doesn’t match literature values
– “Consistent with” instead of “confirmed as”
– No identity testing performed

PURITY (HPLC Analysis)

What it shows: Percentage of pure active compound vs. impurities/byproducts.

How it’s tested:
– HPLC (High-Performance Liquid Chromatography): Separates compound and measures each component

What GOOD looks like:
– [ ] Purity percentage clearly stated (e.g., “98.2%”)
– [ ] Minimum specification listed (usually ≥98%)
– [ ] Result meets or exceeds specification
– [ ] Main peak identified and quantified
– [ ] Impurities listed by percentage

Red Flags:
– Purity listed as “high” without percentage
– Purity below 95% (unacceptable)
– No comparison to specification
– Impurities not identified
– Same result for multiple batches (statistically unlikely)

ENDOTOXIN (Bacterial Contamination)

What it shows: Level of bacterial toxins present. Critical for research that may involve sensitive cell lines.

How it’s tested:
– LAL (Limulus Amebocyte Lysate) Test: Detects endotoxins at parts-per-billion sensitivity

What GOOD looks like:
– [ ] Result clearly stated (e.g., “<5 EU/mg” or “0.5 EU/mL”)
– [ ] Method specified (LAL test acceptable)
– [ ] Limit of detection stated
– [ ] Result below acceptable threshold (typically <10 EU/mg)

Red Flags:
– “Not detected” without actual limit
– Endotoxin level >100 EU/mg
– No endotoxin testing performed
– Method not specified

STERILITY (Microbial Contamination)

What it shows: Absence of living bacteria, fungi, or other microorganisms.

How it’s tested:
– Membrane filtration or culture: Sample incubated to grow any present microbes

What GOOD looks like:
– [ ] Result states “STERILE” or “No Growth Detected”
– [ ] Testing method specified (membrane filtration preferred)
– [ ] Incubation conditions documented
– [ ] Test performed within 30 days of shipment

Red Flags:
– “Likely sterile” or vague language
– Test not performed
– Positive growth results (automatic rejection)
– Old sterility test (>6 weeks)

APPEARANCE (Physical Inspection)

What it shows: Visual characteristics confirm proper synthesis and storage.

What GOOD looks like:
– [ ] Description matches expected appearance (e.g., “white lyophilized powder” for most peptides)
– [ ] No discoloration noted
– [ ] No visible particulates mentioned
– [ ] Consistent with previous batches

Red Flags:
– Unexpected color (yellowing, browning, discoloration)
– Clumping or crystallization noted
– Oily or wet appearance
– Changes in appearance between batches

pH (Acidity/Basicity)

What it shows: pH of reconstituted solution confirms proper chemical form.

What GOOD looks like:
– [ ] pH value clearly stated (e.g., “pH 4.2-4.8”)
– [ ] Result within expected range for compound
– [ ] pH consistent across batches
– [ ] Test performed with calibrated equipment

Red Flags:
– pH outside typical range (usually 3.5-7.5 for peptides)
– Extreme pH (very acidic or basic)
– No pH data provided
– pH dramatically different from previous batches

BATCH NUMBER & TRACKING

What it shows: Unique identifier linking this COA to the exact package you received.

What GOOD looks like:
– [ ] Batch number matches label on your vial/container
– [ ] Batch number is unique (not repeated)
– [ ] Batch number includes date code (e.g., “2026-04-A1” = April 2026, first batch)
– [ ] You can reference batch number in correspondence

Red Flags:
– Batch number missing
– Doesn’t match your label
– Same batch number used repeatedly
– Batch number format unclear

LAB INFORMATION

What it shows: Which lab performed testing. Critical for verification.

What GOOD looks like:
– [ ] Testing lab name clearly stated (not “Supplier’s Lab”)
– [ ] Lab address and contact info provided
– [ ] Lab is third-party (independent from supplier) OR supplier has accreditation noted
– [ ] Lab has published accreditations (ISO 17025, etc.)
– [ ] You can contact lab independently to verify

Red Flags:
– Lab name missing or vague
– Only supplier’s internal lab used
– No contact information
– Lab cannot be independently verified
– Lab changes frequently between batches

THE 5-SECOND COA CHECK

When you receive a COA, immediately verify these five critical points:

1. Batch Number
– [ ] Does it match your vial label?

2. Molecular Weight (Identity)
– [ ] Does MS show correct molecular weight?

3. Purity
– [ ] Is HPLC purity ≥98%?

4. Third-Party Testing
– [ ] Is testing lab name clearly identified (not supplier’s lab only)?

5. Date
– [ ] Is COA recent (within 30 days of purchase)?

If ALL five pass: COA is acceptable. Proceed with use.

If ANY fail: Contact supplier immediately. Do not use compound until resolved.

Common COA Red Flags Summary

Red Flag What It Means Action
Missing batch number Can’t verify you have the tested batch Don’t use—contact supplier
Purity <95% Significant contamination/degradation Don’t use—request replacement
No MS data Compound identity not confirmed Don’t use—request full analysis
“Supplier tested only” No independent verification Acceptable only with long track record
Endotoxin >100 EU/mg High bacterial contamination risk Don’t use for sensitive applications
No sterility data Microbial contamination unknown Verify supplier policy
Same results across batches Data appears copied/fabricated Request new testing
Appearance changed May indicate degradation or contamination Don’t use—investigate

When to Request a New COA

Request a replacement or new testing if:

  • Results don’t match compound specifications
  • Batch number doesn’t match your label
  • COA is older than 30 days from your purchase
  • You notice physical changes in the compound (color, crystallization)
  • COA is missing any major section
  • Lab credentials cannot be independently verified

Understanding Your Supplier’s Testing Philosophy

Premium suppliers provide:
– Batch-specific COAs (not generic templates)
– Third-party testing results
– HPLC + MS for identity confirmation
– Endotoxin and sterility testing
– Recent test dates

Acceptable suppliers provide:
– Batch-specific COAs
– Mix of third-party and internal testing
– HPLC for purity only
– Selective endotoxin/sterility testing

Avoid suppliers that provide:
– Generic COAs (same for all batches)
– Internal testing only
– Missing major test sections
– Undated or old COAs
– Lab information that can’t be verified

About Artemis Labs

At Artemis Labs, every batch comes with a comprehensive, batch-specific COA that passes all checks on this reference guide:

  • ✓ Unique batch number with date coding
  • ✓ MS + HPLC confirmation of identity and purity (≥98%)
  • ✓ Third-party lab testing (fully independent)
  • ✓ Endotoxin, sterility, and appearance data
  • ✓ Lab contact information provided
  • ✓ Recent test dates (within 2 weeks of shipment)

We believe your research deserves full transparency. Download our sample COA from your account dashboard.

Save this guide. Reference it every time you receive a COA.

Questions? Contact our research support team at research@artemispeptides.com.

Last Updated: May 20, 2026
Not for human consumption. Research purposes only. These statements have not been evaluated by the FDA.

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