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⚠ Research Use Only: All content is intended strictly for educational and scientific research purposes. Not for human consumption or clinical use.
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<p style="font-size:13px;color:#888;letter-spacing:.05em;text-transform:uppercase;margin-bottom:8px;">Regulatory & Sourcing · Quality Documentation
<h1 style="font-size:32px;font-weight:700;line-height:1.25;margin-bottom:16px;color:#111;">Understanding Certificates of Analysis (CoAs) for Research Compounds
<p style="font-size:16px;color:#444;line-height:1.6;">The Certificate of Analysis is the most important document in research peptide procurement. This guide explains every field you will encounter on a CoA, how to interpret the data, and what red flags to watch for — enabling researchers and procurement teams to evaluate compound quality with confidence.
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📅 Published: May 2026⏱ Read time: ~7 min🔬 Category: Quality & Documentation
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<p style="font-size:13px;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:#555;margin-bottom:12px;">Table of Contents
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What is a Certificate of Analysis?
CoA fields explained
Reading the HPLC data
Reading the mass spectrometry data
Net peptide content explained
CoA red flags
FAQ
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:16px;">What is a Certificate of Analysis?
<p style="margin-bottom:16px;">A Certificate of Analysis (CoA) is a document issued by a supplier or manufacturer that reports the analytical test results for a specific batch of a compound. For research peptides, the CoA certifies identity (correct sequence), purity (proportion of target compound), and physical characteristics (appearance, moisture) — providing the researcher with the information needed to assess whether the compound meets their experimental requirements.
<p style="margin-bottom:16px;">A CoA is batch-specific — it should correspond to the actual lot of compound shipped, not to a historical or representative sample. Lot-specific CoAs are the minimum standard for research-grade peptide documentation.
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:16px;">CoA Fields Explained
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| CoA Field |
What it Means |
What to Check |
| Product name |
Common and/or IUPAC name of the compound |
Matches your order exactly |
| Sequence |
Full amino acid sequence (single or three-letter code) |
Correct sequence for your compound |
| Molecular weight (theoretical) |
Calculated MW from sequence |
Matches published literature value |
| Molecular weight (measured) |
MS-measured MW for this lot |
Matches theoretical within instrument tolerance |
| Purity (%) |
HPLC area percentage of main peak |
≥95% for standard research use |
| Net peptide content (%) |
Actual peptide fraction of gross weight |
Use for concentration calculations — not gross weight |
| Lot / Batch number |
Unique identifier for this synthesis batch |
Matches vial label exactly |
| Appearance |
Visual description (white/off-white lyophilised powder) |
Matches actual vial contents |
| Expiry / Retest date |
Stability period under stated storage conditions |
Within valid period at time of use |
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:16px;">Reading the HPLC Data
<p style="margin-bottom:16px;">A CoA should include the actual HPLC chromatogram image, not just the numerical purity figure. When reviewing the chromatogram:
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Main peak dominance: The target peptide peak should be clearly the largest feature. In a 98% pure compound, the main peak should visually dominate with only minor shoulders or impurity peaks.
Peak symmetry: A symmetrical, Gaussian-shaped main peak indicates a single well-resolved compound. Broad, asymmetric, or shouldered peaks may indicate co-eluting impurities or multiple conformational species.
Baseline resolution: Impurity peaks should be baseline-resolved from the main peak where possible. Unresolved peaks indicate limitations in the analytical method that may cause underreporting of impurities.
Retention time plausibility: For experienced researchers, the retention time of the main peak should be consistent with the peptide’s expected hydrophobicity under the stated gradient conditions.
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:16px;">Reading the Mass Spectrometry Data
<p style="margin-bottom:16px;">The MS data confirms molecular identity by measuring the mass-to-charge ratio of the peptide ions. For research peptides:
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[M+H]+ ion: The singly protonated molecular ion. Its m/z value equals the molecular weight + 1. For small peptides (under ~2,000 Da) this is typically the dominant ion.
Multiply charged ions: Longer peptides (like tirzepatide or retatrutide at ~4,000+ Da) produce multiply charged ions — [M+2H]²+, [M+3H]³+, etc. The presence of a consistent charge envelope confirms the correct mass.
Calculated vs observed: The CoA should state both the theoretical molecular weight and the experimentally measured value. The difference should be within ±0.1 Da for low-resolution MS or ±0.005% for high-resolution MS.
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:16px;">Net Peptide Content Explained
<p style="margin-bottom:16px;">Lyophilised peptides always contain more than pure peptide. Counter-ions from synthesis (TFA or acetate, introduced during purification) and residual water both contribute to gross weight. Net peptide content corrects for these non-peptide components.
<p style="margin-bottom:16px;">A typical research-grade peptide has net peptide content of 70–85%. This means:
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1.0 mg gross weight × 78% net peptide = 0.78 mg actual peptide
Target concentration: 1 mg/mL requires 1.0 mg gross ÷ 0.78 = 1.28 mg gross to add per mL
<p style="margin-bottom:16px;">Always use this correction factor in your concentration calculations. Failure to do so introduces systematic underdosing across all experiments using the compound.
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:16px;">CoA Red Flags
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🚩 No chromatogram image — purity number stated without supporting chromatogram data
🚩 Generic or undated CoA — not lot-specific, or same CoA used for all products
🚩 No MS data — identity not analytically confirmed
🚩 Purity stated as “≥98%” with no decimal precision — suggests estimated rather than measured purity
🚩 No net peptide content stated — prevents accurate concentration calculations
🚩 Lot number on CoA doesn’t match vial label — traceability failure
🚩 Molecular weight stated without measured value — theoretical only, not analytically verified
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<h2 style="font-size:24px;font-weight:700;color:#111;border-left:4px solid #888780;padding-left:14px;margin-bottom:20px;">Frequently Asked Questions
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<summary style="font-weight:600;cursor:pointer;">How long should I keep CoA records?
<p style="margin-top:12px;font-size:14px;color:#444;">For research destined for publication, keep CoA records for the duration of the study plus at least 5–10 years afterward — in line with most institutional research data retention policies. If results are challenged, the CoA provides documentary evidence of compound identity and quality at the time of experimentation.
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<summary style="font-weight:600;cursor:pointer;">Should I verify CoA data in my own lab before use?
<p style="margin-top:12px;font-size:14px;color:#444;">For high-stakes research, independent analytical verification is good practice — particularly for novel or unfamiliar compounds. A simple analytical HPLC run against the supplier’s stated retention time can confirm purity. For identity, LC-MS access is needed. Core analytical facilities at most research institutions can perform both analyses for a modest fee.
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Disclaimer: For educational and scientific research purposes only. Not for human consumption or clinical application. Alluvi Peptides does not provide legal or regulatory advice.
