Residual Solvent Testing
Analysis detecting trace amounts of organic solvents remaining from the manufacturing process. Solvents used in peptide synthesis and purification (such as DMF, DCM, and TFA) must be below ICH-specified limits in the final product to ensure patient safety.
Technical Context
ICH Q3C classifies solvents: Class 1 (should be avoided — carcinogens/environmental hazards: benzene, carbon tetrachloride), Class 2 (should be limited — non-genotoxic toxicity: DMF limit 880ppm, DCM limit 600ppm, methanol limit 3000ppm, acetonitrile limit 410ppm, TFA — not classified but typically limited to <0.1%), Class 3 (low toxic potential, limits ≥5000ppm: acetone, ethanol, ethyl acetate). Testing by headspace gas chromatography (HS-GC) — volatile solvents partition into the headspace above a heated sample and are separated/quantified by GC-FID or GC-MS. For SPPS-derived peptides, typical residual solvents include: DMF, DCM (from synthesis), acetonitrile, TFA (from HPLC purification), and diethyl ether (from precipitation). Residual solvent specifications are defined in the drug substance specification and verified in release testing.