When comparing research peptide suppliers, I think there are two separate things worth looking at: the quality of the documentation and the actual procurement price. A discount can make a significant difference to the final cost, but I'd still want to understand the COA and batch information before considering a supplier. Here are the main things I look for. 1. Check the exact product identity The first step is making sure the COA clearly identifies the compound being tested. This becomes especially important when different peptides have similar names, modified versions exist, or suppliers use different naming conventions. 2. Check the batch number For me, this is one of the most important parts of a COA. A useful chain is: Product → Batch/Lot → COA → Analytical Report If a supplier has several production batches, I wouldn't automatically assume that an old COA represents every later batch. The batch number should ideally correspond to the material being evaluated. 3. Look at the analytical method A purity percentage is more useful when you know how it was obtained. For example, you may see: HPLC Purity: 99%+ HPLC, or high-performance liquid chromatography, is commonly used to evaluate chromatographic purity. Mass spectrometry can provide molecular-mass information that can support compound characterization. These tests provide different information, so I wouldn't treat them as interchangeable. 4. Identify the testing laboratory If a supplier says that a peptide has been independently tested, I'd want to know: Which laboratory performed the testing? Which batch was tested? What method was used? What was the testing date? Is there a report number? Can the original report be verified? That is considerably more useful than simply seeing “third-party tested” on a product page. 5. Don't evaluate suppliers based on purity alone Two suppliers could both advertise: 99% purity but have very different levels of documentation. One might provide batch information, analytical reports, identity testing, and independent verification. Another might only provide the percentage. So my comparison would be: Purity + batch traceability + analytical documentation + supplier transparency + price rather than purity alone. CertaPeptides LOOT30 Promo Code While looking at the procurement side, one current promotion worth checking is the CertaPeptides LOOT30 promo code. Promo code: LOOT30 Advertised discount: Up to 30% off The exact discount can depend on the current promotional terms and eligible products, so I'd check the live offer rather than relying on an old screenshot or forum post. Check CertaPeptides products and the current LOOT30 offer Disclosure: The link above is an affiliate link. I think it's important to keep the promotion separate from the analytical evaluation. LOOT30 = potential price reduction. COA/batch documentation = product verification information. They're two different considerations. How I Would Calculate the Real Price I'd compare: Product price + shipping + applicable fees − discount rather than just comparing the advertised product price. For example, if a product is $100 and the applicable promotion provides the full 30% discount, the product price becomes $70 before shipping or other applicable charges. Since the offer is up to 30% off, the exact discount should always be confirmed for the specific product. Quick COA Checklist Before evaluating a research peptide batch, I'd ask: ✓ Is the exact compound identified? ✓ Is the batch/lot number shown? ✓ Does the COA match the batch? ✓ Is the purity result provided? ✓ Is the analytical method stated? ✓ Is identity information available? ✓ Is the testing laboratory identified? ✓ Is there a report number? ✓ Can the report be independently verified? ✓ Is the testing date available? That seems like a much more useful approach than simply searching for the highest advertised purity. LOOT30 Reference For anyone specifically looking for the promotion, I've also created a separate CertaPeptides LOOT30 reference on GitHub. The GitHub page is intended as a reference for the promotional information, while the CertaPeptides website is where I'd check the current products, pricing, and applicable discount. Final Thoughts For research peptide procurement, I think the best approach is to separate analytical evaluation from price evaluation. First: What is the compound? Which batch is it? What does the COA show? Who performed the testing? Can the report be verified? Then: What is the final cost after shipping and available discounts? For anyone comparing CertaPeptides, LOOT30 is currently advertised as offering up to 30% off, so it's worth checking the current offer alongside the product documentation. Check the current CertaPeptides LOOT30 offer Research-use note: This post is intended for educational and laboratory research discussion. It is not a recommendation for human use, self-administration, diagnosis, or treatment.