- Caffeine assay (HPLC)
- Caffeine content by HPLC; for standardized extracts this sets how much extract each batch needs.
- Origin testing
- Radiocarbon (14C) or stable-isotope ratio testing can tell plant-derived caffeine from synthetic; ask whether the supplier tests lots or can provide results.
- Residual solvents
- Solvents from decaffeination and purification (for example ethyl acetate or methylene chloride, or none for CO2 processes), against USP <467> or the buyer's limits.
- Pesticide residues
- Multi-residue screen for plant extracts, by GC-MS/MS and LC-MS/MS.
- Heavy metals
- Lead, arsenic, cadmium and mercury by ICP-MS, checked against the supplier specification and the buyer's own limits.
- Microbiology
- Total plate count, yeast and mold, coliforms or E. coli, and Salmonella, against the supplier specification.