GHK-Cu — peptide purity plus copper stoichiometry.

GHK-Cu is biologically active because of the copper chelate, not just the peptide. The Gly-His-Lys tripeptide on its own (without bound copper) has different activity than the GHK-Cu complex. Vials labeled 'GHK-Cu' with copper stoichiometry of 0.5:1 are functionally half-strength GHK-Cu plus half-strength bare peptide. ICP-MS quantification confirms whether the product is the chelated complex or partially uncomplexed peptide.

Yes. Topical formulation matrices add complication — the cream / serum base interferes with HPLC quantification, requiring sample prep (extraction, dilution) before assay. We've validated methods for typical cosmetic bases (water + emulsifier + glycerin + oil phase). Send the finished product (one container or 30 g equivalent) plus the formulation ingredient list. Pricing matches the standard panel.

92-99 % is typical for research-grade and cosmetic-grade material. Below 90 % usually indicates incomplete peptide synthesis or significant degradation. The chelated copper is removed by the HPLC mobile phase, so what's measured is the peptide purity independent of Cu content — copper stoichiometry is a separate measurement via ICP-MS.

Only for injectable-grade material. Topical / cosmetic GHK-Cu does not legally or practically require LAL endotoxin testing. Topical formulations should have USP <51> preservative-efficacy testing instead — that confirms the finished cream survives microbial challenge over 28 days.

Yes. Accelerated stability time-point pulls at Day 7, 14, 28, 56 at 25 °C / 40 °C / 60 % RH. Bundled into the Topical Full Stack panel; available standalone at $99 per pull. We report purity, copper stoichiometry, and color (visual) at each time point.

Other labs that test GHK-Cu typically only run HPLC purity for the peptide and skip the copper stoichiometry, treating it as an organic-chemistry purity panel. Our Identity + Cu Stoichiometry panel at $449 adds the ICP-MS Cu quantification, which is the more important measurement for product authenticity. Pricing reflects that — single-panel reports the actual GHK-Cu quality rather than 'just the peptide'.