> For the complete documentation index, see [llms.txt](https://peptara-labs.gitbook.io/peptaralabs-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://peptara-labs.gitbook.io/peptaralabs-docs/02-how-to-read-a-coa.md). # 02 how to read a coa A Certificate of Analysis, or COA, is the lab document that describes what a specific batch of material actually contains. For research peptides it is the primary way to check that a vial matches its label before any work begins. This page explains each section a COA typically reports, what each test measures, and how the sections relate to one another. It is a reference for reading the document, not guidance on how to use any compound. Read every section together rather than fixing on one number. A high purity figure means little if the identity test does not confirm the compound is the one named, and neither matters if the document cannot be tied to the batch in front of you. The sections below are ordered the way most COAs present them. ## Purity (HPLC) Purity answers a narrow question: of the material detected, how much of it is the intended peptide rather than other peptide-related species. The standard method is High Performance Liquid Chromatography, or HPLC, which separates the sample into components as they pass through a column and produces a chromatogram of peaks. The main peak is the target peptide. The smaller peaks are impurities such as truncated sequences, deletion sequences, or related byproducts of synthesis. The purity value is reported as a percentage, calculated from the area of the main peak relative to the total peak area. A higher percentage means a larger share of the detected material is the named peptide. A lower figure is not automatically a defect, but it does mean a larger share of the detected material is something other than the named peptide, and the chromatogram is worth examining to see how that remainder is distributed. One limit to keep in mind: HPLC purity describes the peptide-related content the method detects. It does not, on its own, confirm the identity of the main peak. That is the job of the next test. ## Identity (Mass Spectrometry / LC-MS) Identity answers a different question from purity: is the main peak actually the peptide named on the label. A sample can be highly pure and still be the wrong compound, because purity only tells you the main peak is dominant, not what it is. Identity confirmation closes that gap. The method is mass spectrometry, often run as LC-MS, which couples liquid chromatography to a mass spectrometer. The instrument measures the mass of the molecule and compares the observed mass against the theoretical mass calculated from the peptide's known sequence. When the observed mass matches the expected mass within the method's tolerance, the COA reports identity as confirmed. This is why purity and identity are separate line items and why both belong on a complete COA. Purity tells you how much of the detected material is the main species. Identity tells you that the main species is the molecule you expect. A document that reports one without the other leaves a real question unanswered. ## Sterility Sterility testing addresses whether the material is free from viable microbial contamination. It is a presence or absence question rather than a graded percentage. A COA will typically state the result as passing or failing a sterility assessment for the batch. Sterility is reported separately from purity and identity because it measures a different category of risk entirely. Purity and identity concern the chemistry of the peptide itself. Sterility concerns biological contamination introduced during synthesis, handling, or filling. Both kinds of information matter, and a thorough COA reports them as distinct results. ## Endotoxin Endotoxin testing measures bacterial endotoxins, which are fragments associated with the outer membrane of certain bacteria. Endotoxins can be present even after a material reads as sterile, because sterility concerns living organisms while endotoxin concerns these specific bacterial components that persist independently of whether organisms are still viable. For that reason endotoxin is reported as its own line, not folded into the sterility result. On a COA the endotoxin result is usually given as a measured level against a defined limit, often expressed in endotoxin units. The document states the limit the batch was tested against and whether the measured value falls within it. As with sterility, treat this as a distinct check rather than something the purity number already covers. ## Heavy Metals Heavy metal screening checks for trace contamination by metallic elements that can be introduced through raw materials, reagents, or equipment during manufacturing. This is a contamination screen, separate again from the peptide chemistry that purity and identity describe. A COA reports heavy metal results as measured levels against defined limits, and may list individual elements or report against a combined threshold. The relevant question when reading this section is whether the measured values sit within the stated limits for the batch. Like sterility and endotoxin, heavy metal screening adds a layer of information that the purity figure alone does not capture. ## Per-Batch vs Per-Product This distinction separates a meaningful COA from a decorative one. A genuine COA is tied to a specific batch or lot, identified by a batch number or lot number printed on the document. It reports the test results for that production run, and only that run. A per-product COA, by contrast, is a single generic document presented for a compound in general, with no batch or lot number connecting it to the vial you hold. Manufacturing varies from run to run, which is exactly why the results that matter are the ones measured on the batch you received. When you read a COA, find the batch or lot number first and confirm it corresponds to your material. If there is no batch identifier, the document is describing the idea of the compound rather than the specific material in hand. ## Who Tested It The strength of a COA depends in part on who produced it. A self-reported COA, generated by the same party selling the material, carries an obvious conflict of interest: the seller is grading its own work. A COA from an independent third-party laboratory is stronger evidence, because the testing party has no stake in the result. Stronger still is testing aligned to a recognized competence standard such as ISO/IEC 17025, which addresses the technical competence of testing laboratories. Alignment to that kind of standard signals that the lab's methods and quality systems have been assessed against an external benchmark, rather than resting on the lab's own assurances. When reading a COA, note which laboratory ran the tests, whether that laboratory is independent of the seller, and whether it operates to a recognized standard. ## How Peptara Labs Reports This Peptara Labs publishes a third-party, per-batch Certificate of Analysis for every compound it ships. Each COA ties to a specific batch and reports HPLC purity, mass spectrometry identity, sterility, endotoxin, and heavy-metal screening, so the document in your hands corresponds to the material in your hands. You can review the published certificates on the [Peptara Labs COA page](https://www.peptaralabs.io/coa). Research peptides are research compounds, not approved medicines. A COA tells you what a batch contains and how it was verified. It does not tell you how a compound should be used, and nothing on a certificate should be read as direction for use. For more on the brand and its catalog, see [peptaralabs.io](https://www.peptaralabs.io/). --- # 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 by asking a question. 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