Table 1.

Different classes of solvents in pharmaceutical products and their suggested concentration limits [25, 26, 27].

Class 1 Solvents to be avoided		Class 2 Solvents to be limited		Class 3 Solvents with low risk
Solvent	Limit (ppm)	Solvent	Limit (ppm)	Solvent	Limit (%w/w)
Benzene	2	Acetonitrile	410	Acetic acid	0.5
Carbon tetrachloride	4	Chlorobenzene	360	Anisole	0.5
1,1-Dichloroethene	8	Chloroform	60	Butyl acetate	0.5
1,2-Dichloroethane	5	Cyclohexane	3880	Formic acid	0.5
1,1,1-Trichloroethane	1500	Dichloromethane	600	Heptane	0.5
		Hexane	290	Isobutyl acetate	0.5
		Methanol	3000	Methyl acetate	0.5
		Sulfolane	160	Pentane	0.5
		Tetralin	100	Propyl acetate	0.5
		Xylene	2170	Tetrahydrofuran	0.5