> For the complete documentation index, see [llms.txt](https://docs.rplpeptides.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rplpeptides.com/docs/faq/coa-faq.md). # Certificate of Analysis (COA) FAQ ## 1. What information is included on an RPL Peptide COA? Each COA includes: product name, batch/lot number, manufacturing date, expiry date, HPLC purity (at 214 nm and 254 nm), peptide content (as determined by HPLC), counterion content (TFA⁻ or acetate⁻ depending on purification), water content (Karl Fischer), appearance description, molecular weight confirmation (LC-MS), and storage conditions. ## 2. How is COA data generated? Each batch undergoes testing by RPL Peptide's quality control laboratory. Analytical methods are validated per ICH Q2(R1) guidelines. COAs are signed by the QC manager and can be traced back to raw analytical data. ## 3. What is the difference between HPLC purity and peptide content? HPLC purity (area%) measures the target peptide peak area relative to all detected peaks in the chromatogram. Peptide content refers to the actual peptide mass percentage in the lyophilized powder, accounting for bound water, residual TFA counterions, and other non-peptide components. ## 4. Do you provide batch-specific COAs? Yes. Every order is fulfilled from a specific batch, and the corresponding COA is included with shipment. Batch-specific HPLC chromatograms and LC-MS data are also available upon request. ## 5. What purity specifications does RPL Peptide guarantee? Standard purity is ≥98% at 214 nm. Some products may be supplied at ≥95% or ≥99% depending on the specific product. The exact specification is stated on each product's COA and Technical Data Sheet. ## 6. How do I interpret the HPLC chromatogram on a COA? The chromatogram shows absorbance at 214 nm (peptide bond detection) versus retention time. The main peak represents the target peptide. Any additional peaks are impurities (deletion sequences, truncations, oxidation products). The purity percentage is calculated as: (Main Peak Area / Total Peak Area) × 100%. ## 7. What is the TFA content, and why does it matter? TFA (trifluoroacetic acid) is a residual counterion from HPLC purification. It contributes to the total mass of the lyophilized product. TFA content is typically 5–15% by weight and varies by peptide sequence. For cell-based assays, TFA may affect viability; a TFA-to-acetate exchange can be requested for custom orders. *** *For additional COA questions, contact * --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.rplpeptides.com/docs/faq/coa-faq.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.