US Peptide Science vs Onyx Research Peptides
US Peptide Science and Onyx Research Peptides are two of the more recognized domestic research peptide suppliers. Both carry a broad catalog and publish purity documentation. This comparison examines the key differentiators researchers should evaluate when selecting a supplier for their laboratory work.
| Attribute | US Peptide ScienceUs | Onyx Research Peptides |
|---|---|---|
| US-Based Operations | Yes — domestic synthesis and QC | Domestic distribution; synthesis origin varies |
| Purity Standard | ≥98% HPLC; most >99% | ≥98% HPLC |
| Third-Party COA | Independent lab COA with every batch | COA provided; lab source disclosed on request |
| Mass Spec Verification | MS confirmation on all compounds | Available; product-dependent |
| Product Selection | Focused catalog: core research peptides | Broad catalog including ancillary compounds |
| Shipping Speed | Same/next-day US dispatch | Standard US fulfillment timelines |
| Packaging | Cold-chain; inert-gas sealed lyophilizate | Standard research packaging |
| Pricing | Competitive; quality-tier pricing | Comparable range; volume discounts available |
Purity Documentation & Testing Transparency
Both suppliers publish Certificates of Analysis. The key differentiator for reproducible research is whether the COA is produced by a genuinely independent third-party lab (not the same entity handling synthesis) and whether mass spectrometry data is routinely included alongside HPLC chromatograms. US Peptide Science provides HPLC and MS data from independent accredited US laboratories for every batch, including chromatogram images. Researchers designing studies with strict QC requirements should verify the COA chain of custody with any supplier before ordering.
Product Catalog Coverage
Onyx Research Peptides maintains a broader catalog that includes some ancillary compounds beyond core peptides. US Peptide Science maintains a more curated selection focused on the highest-demand research peptides — BPC-157, TB-500, Semaglutide, Ipamorelin, CJC-1295, Tesamorelin, and related compounds. Researchers working exclusively in the mainstream peptide categories will find full coverage at either supplier; those needing niche or novel compounds may find Onyx's broader catalog advantageous.
Shipping & Cold Chain
Temperature stability during transit is a significant variable for peptide integrity, particularly for longer or more complex sequences. US Peptide Science ships temperature-sensitive compounds with cold-chain packaging and inert-gas sealed lyophilized product. Researchers in warmer climates or ordering during summer months should specifically confirm cold-chain handling practices with any supplier prior to ordering.
Bottom Line
For researchers prioritizing full purity transparency, domestic supply chain, and cold-chain shipping reliability, US Peptide Science represents a strong default choice for core research peptides. Onyx Research Peptides is a credible alternative with a broader catalog for researchers needing compounds outside the mainstream catalog. The most important step for any researcher is to independently verify COA documentation before placing a first order with any supplier.
Browse Our Catalog
View all available research peptides with full COA documentation.