Confirm the commercial identity
A useful first check includes the exact salt form, CAS 122628-50-6, molecular formula, appearance and assay method. For relevant food-grade projects, the FDA GRAS response describes a reddish-brown crystalline powder containing at least 98% PQQ disodium salt, but a buyer must still confirm whether the offered grade and intended use fit the applicable notice and local rules.
Purity is only one line of the specification
Review moisture, residual solvents, lead, arsenic, cadmium, mercury and microbiological limits together with identity and assay. Fermentation- or synthesis-related impurities, particle behavior, light sensitivity and the analytical reference standard may also affect qualification. Stability and packaging should be evaluated for the intended shelf life and climate.
Separate technical supply from finished-product claims
State whether the project is a beverage, supplement, premix, feed or research formulation, together with daily use level, market and required certifications. Regulatory status and permitted claims vary by country and application. Supplier documentation supports evaluation, but it does not authorize a finished-product claim or dosage automatically.