Our Commitment to Quality
At Phase 1 Peptides, products undergo HPLC purity analysis and LC-MS identity confirmation by independent third-party analytical laboratories before dispatch. Lot-specific results are published as Certificates of Analysis. Materials that do not meet our analytical purity standard are not accepted.
Core Testing Methods
Lot-level analytical verification covers the two metrics that matter most to researchers:
1. Purity Analysis (HPLC)
High-Performance Liquid Chromatography (HPLC) separates the components of a sample and measures the percentage that is the target peptide. Compounds are accepted only when they clear our HPLC purity threshold — synthesis-related impurities must fall below our analytical acceptance standard. Purity is the headline metric on each Certificate of Analysis. For a detailed walkthrough of chromatogram anatomy, peak area normalization, and impurity peak interpretation, see How to Read HPLC Purity Data.
2. Identity Verification (Mass Spectrometry)
Mass spectrometry (MS) analyzes the molecular weight of the peptide and compares it against the theoretical value for the expected structure. A match confirms you are receiving exactly the compound listed on the label, not a mislabeled or misidentified material.
Additional Analyses
Select compounds also include further testing where applicable, such as:
- Net Peptide Content — measures the actual peptide mass in the vial after accounting for water, salts, and counterions (like acetate or TFA). Useful for precise concentration calculations.
Other analyses you may see on some COAs — sterility, endotoxin (LAL), heavy metals screening (ICP-MS) — are industry-standard tests performed by specialized facilities for compounds intended for specific research uses. These are not performed routinely on all batches.
What Does HPLC Purity Mean for Research Peptides?
An HPLC purity percentage represents the proportion of the UV-detected chromatographic area attributable to the target peptide. The remaining fraction may include:
- Truncated sequences from incomplete synthesis
- Deletion peptides missing one or more amino acids
- Oxidized or deamidated variants
For most research applications, 95% purity is considered acceptable. Phase 1 Peptides applies a stringent HPLC purity acceptance threshold that exceeds this standard, providing greater confidence that observed experimental effects reflect the target compound rather than trace impurities.
Publicly Available COAs
Every product on our site includes a downloadable Certificate of Analysis (COA) with the specific test results for that batch. Transparency is not optional — it is foundational to how we operate. Browse our Lab Tests to see lot-specific test results for products we carry. What is the difference between HPLC purity testing and mass spectrometry identity testing?
HPLC purity measures the percentage of the sample that is the target peptide by separating components and comparing peak areas. Mass spectrometry confirms the compound's molecular weight, verifying it is chemically what it claims to be. Both tests answer different questions: "How pure is the sample?" (HPLC) and "Is it the right compound?" (MS). Research-grade COAs should include results from both tests.
What does HPLC purity mean in practice for research peptides?HPLC purity is expressed as the percentage of the UV-detected area in the chromatogram attributable to the target peptide peak. The remaining fraction may include truncated synthesis sequences, oxidized variants, or deletion peptides. For most research applications, 95% purity is considered an acceptable baseline; Phase 1 Peptides applies a purity acceptance threshold that exceeds this standard, providing greater confidence that observed experimental effects are attributable to the target compound rather than trace impurities.
What is net peptide content, and why does it differ from HPLC purity?Net peptide content measures the actual mass of peptide per unit weight of lyophilized powder, accounting for water, salts, and counterions — typically TFA (trifluoroacetate) or acetate from HPLC purification. A vial labeled 10 mg with 75% net peptide content contains approximately 7.5 mg of active peptide. HPLC purity is a chromatographic measurement of compound identity; net peptide content is a gravimetric correction for non-peptide mass. Both are important for accurate concentration calculations.
What additional analytical tests may appear on a research peptide COA?Beyond HPLC purity and mass spectrometry identity, some COAs include net peptide content, moisture content (Karl Fischer titration), residual solvent data, endotoxin testing (LAL), and heavy metals screening (ICP-MS). These additional tests are more common for compounds used in specialized research protocols with stringent analytical requirements, and are not performed routinely on all research peptide batches.
Not sure how to read the numbers? See Understanding Certificates of Analysis for a field-by-field walkthrough.
See Also
- How to Verify a Research Peptide COA
- How to Read HPLC Purity Data
- Lyophilization & Freeze-Drying
- Peptide Storage & Stability
- Peptide Half-Life Reference
- LC-MS Identity Confirmation — dedicated guide to reading mass spec results on a COA
- HPLC vs LC-MS: A Researcher's Comparison — how HPLC and LC-MS work together in research peptide batch documentation
- TFA Content & Salt Form Interpretation — how TFA counterions affect net peptide content and what it means for COA interpretation
- What Research Use Only Means — what RUO designation means for analytical documentation and laboratory context
- Peptide COA Review Checklist — structured field-by-field checklist for reviewing COA documentation