Understanding Certificates of Analysis
A Certificate of Analysis (COA) is the single most important document for verifying peptide quality. This guide explains every data field, how to interpret results, and what red flags to watch for.
What is a COA?
A Certificate of Analysis is a document issued by a testing laboratory that reports the results of quality control testing performed on a specific batch of a chemical compound. For research peptides, a COA typically includes purity analysis, identity confirmation, and safety testing data.
COAs serve as the primary mechanism for researchers to verify that the compound they received matches the specifications claimed by the supplier. Without a valid COA, there is no independent confirmation of what a vial actually contains.
At Halo Peptides, every batch is tested by Janoshik Analytical, an independent third-party laboratory. This separation between supplier and testing lab is essential for unbiased results.
Key Data Fields Explained
High-Performance Liquid Chromatography Purity
HPLC is the gold standard method for determining peptide purity. It separates the target compound from impurities, degradation products, and synthesis byproducts based on their chemical properties.
The result is expressed as a percentage. For research-grade peptides, a purity of 95% or higher is generally acceptable. At Halo Peptides, our average batch purity exceeds 98.5%.
TYPICAL RANGE
98.0% -- 99.5%
Mass Spectrometry Identity Confirmation
Mass spectrometry determines the molecular weight of the compound and confirms its identity. The measured molecular weight is compared against the expected theoretical value for the target peptide.
A result of "CONFIRMED" means the measured mass matches the expected mass within acceptable tolerance (typically within 0.1% of the theoretical value). This confirms you have received the correct compound.
EXPECTED RESULT
CONFIRMED
Endotoxin Testing (LAL)
Endotoxins are bacterial lipopolysaccharides that can contaminate peptide compounds during synthesis. The Limulus Amebocyte Lysate (LAL) test detects and quantifies endotoxin levels.
Results are expressed in Endotoxin Units per milligram (EU/mg). For research-grade peptides, levels below 0.5 EU/mg are considered acceptable. Elevated endotoxin levels can confound research results, particularly in cell culture and immunological studies.
ACCEPTABLE LIMIT
<0.5 EU/mg
Moisture Content
Moisture content measures the residual water in the lyophilized peptide powder. Excess moisture accelerates degradation and can affect accurate weighing.
Results are typically reported as a percentage. Values below 2.0% are acceptable for lyophilized peptides. Higher moisture content may indicate incomplete lyophilization or exposure to humid conditions.
ACCEPTABLE LIMIT
<2.0%
Net Peptide Content
Net peptide content represents the actual amount of active peptide in the total powder weight, accounting for water, counter-ions (such as acetate or TFA salts), and other non-peptide components.
A vial labeled "5mg" with 80% net peptide content contains 4mg of actual peptide. This distinction is important for accurate concentration calculations during reconstitution.
TYPICAL RANGE
75% -- 95%
How to Read Purity Data
The HPLC chromatogram is the most informative part of a COA. Here is how to interpret the key elements:
The largest peak represents the target peptide. Its area percentage relative to all peaks is the reported purity. A single, sharp, well-defined peak indicates a clean synthesis.
Smaller peaks represent impurities -- deletion sequences, truncated fragments, or synthesis byproducts. Their combined area percentage is subtracted from 100% to determine purity.
The time at which the main peak elutes from the column. This should match the expected retention time for the target compound under the stated HPLC conditions.
A symmetrical, Gaussian peak shape indicates good compound behavior. Tailing, fronting, or split peaks may indicate degradation or column issues.
A flat, stable baseline indicates clean separation. A noisy or drifting baseline may indicate contamination or method issues.
Red Flags
When evaluating a COA -- from any supplier -- watch for these warning signs that may indicate unreliable data or poor-quality compounds:
No independent lab name or contact information
Legitimate COAs are issued by named, contactable laboratories. Generic or anonymous COAs cannot be verified.
Purity always reported as exactly 99.0% or 99.9%
Suspiciously round numbers suggest fabricated data. Real analytical results vary between batches.
No batch number or lot identifier
Without a batch number, the COA cannot be traced to a specific production run.
Missing or cropped chromatogram
The HPLC chromatogram is the primary evidence. Its absence or truncation should raise immediate concern.
Same COA used across multiple batches
Each batch should have its own unique COA. Reusing a single document across batches is a serious red flag.
No mass spectrometry data
Without MS confirmation, there is no proof the compound is what it claims to be, regardless of purity.
Test date significantly older than the batch date
If the COA predates the batch by months, it may not represent the actual compound in the vial.
Our Testing Process
At Halo Peptides, we follow a multi-stage quality assurance process designed to provide maximum transparency and confidence in every batch we release:
Synthesis QC
Initial in-house quality control during GMP-compliant synthesis, including crude purity assessment and yield verification.
Internal HPLC Analysis
In-house HPLC testing to confirm the batch meets our minimum purity threshold before sending for independent verification.
Independent Third-Party Testing
Samples are sent to Janoshik Analytical for independent HPLC purity analysis, mass spectrometry identity confirmation, and endotoxin testing.
COA Publication
The full Certificate of Analysis from Janoshik is published in our COA Library and linked directly to the product listing.
Batch Release
Only batches that pass all quality criteria are released for sale. Any batch failing to meet specifications is rejected and destroyed.