In pharmaceutical and allied, use of organic solvents play a critical role throughout the API and FP manufacturing process. The residual solvents are those that are not completely removed after processing. Residual solvents are organic volatile chemicals that are used or produced in the manufacturing process of drug substances, or excipients or in the preparation of drug products.  In addition, many natural occurring plants are used in manufacturing of Natural Health Products and may also contain organic components.

Residual Solvents testing is required to determine that these solvents are not present at threatening levels in order to ensure product quality and safety. The ICH guideline Q3C (R5) and USP <467> provide analytical methods and permissible daily exposure for some of the commonly used solvents.