What do you mean by residual solvent?

Residual solvents are the traces of the solvents left during the manufacturing of drug substances or active pharmaceutical ingredients and excipients. The solvents those are used during the manufacturing process are not completely removed during the manufacturing.

Some common residual solvents are:

•  Acetonitrile
• Chlorobenzene
• Chloroform
• Cyclohexane
•  1,2-Dichloroethene
• 1,2-Dimethoxyethane
• N,N-Dimethylacetamide
• N,N-Dimethylformamide
• 1,4-Dioxane
• 2-Ethoxyethanol
• Ethylene glycol
• Formamide
• Hexane
• Methanol
• 2-Methoxyethanol
• Methylbutylketone
• Methylcyclohexane
• Methylene chloride
• N-Methylpyrrolidone
• Nitromethan