Start with scope, not a copied limit
ICH Q3C defines residual solvents in pharmaceuticals as organic volatile chemicals used or produced in manufacture, and addresses drug substances, excipients and drug products.[1] Its classification is not a universal authorization for food, supplements or cosmetics. Before discussing acceptance, identify the intended product category and destination, then ask which current requirement or justified specification applies to that particular material and use.
Build an analyte list from the complete route
Within its pharmaceutical scope, Q3C links solvent testing to solvents used or produced during manufacture or purification.[1] Ask for extraction, purification, reprocessing and formulation-stage disclosures sufficient to justify the requested list. Do not equate a standard laboratory package with a complete risk assessment. A “water extract” headline should prompt clarification of downstream stages, not an unsupported assumption that every possible organic solvent is absent.
Specify the analytical question
Q3C describes chromatographic techniques such as gas chromatography and calls for an appropriate validated analytical procedure.[1] Ask the laboratory which sampling or injection approach it uses, how the actual extract matrix is handled, and what supports detection and quantification for each requested solvent. A method acronym or instrument model cannot establish suitability for every botanical powder, carrier or liquid preparation.
Read ND with its reporting context
For procurement review, request the numerical result or clearly defined reporting statement, units, method revision and the relevant detection or quantification limit. Ask what “not detected” means in that laboratory’s report. Compare the reporting capability with the proposed acceptance criterion rather than reading ND as absolute zero. Clarify whether a result refers to the supplied preparation and whether sample handling could affect the volatile-analyte question.
Do not turn a qualified exception into a blanket rule
Q3C allows a nonspecific method such as loss on drying when only Class 3 solvents are present and the method is properly validated.[1] That qualified statement is not a license to identify individual solvents from an unexplained LOD value. Equally, it would be wrong to claim Q3C always requires headspace GC for every extract. Request the laboratory’s documented rationale for the chosen procedure and the actual acceptance question.
Release checklist and unresolved items
Before disposition, reconcile the SKU and lot, complete process declaration, justified solvent list, applicable acceptance basis, method suitability, results and reporting capability. Record who reviews exceptions and what additional evidence is needed. No universal residual-solvent limit is proposed here, and no customer dose, test result, solvent-free claim or ZL batch compliance is invented. A supplier statement and a batch-specific measurement remain different kinds of evidence.