Table 5. Comparison of the analytical method among four references and this study.

Studies	Column	Plasma volume	Internal standard	Sample preparation method	Run time	Injection volume
Current Study Results	Thermo Hypersil GOLD	200 µL	Donepezil-D4	LLE (using n-hexane and ethyl acetate)	3 minutes	3 µL
Park, E. J.[13]	Water atlantis HILIC Silica column	200 µL	Cisapride	LLE (using 0.5 M NaOH and methyl tert-butyl ether)	2 minutes	7 µL
Shah, H. J. et al.[14]	Thermo betabasic-C8	500 µL	Escitalopram oxalate	SPE	1.8 minutes	20 µL
Bhateria, M., et al.[15]	Thermo syncronis-C18 column	50 µL	Amantadine hydrochloride	LLE (using methanol)	3 minutes	10 µL
Pilli, N.R.[16]	Chromolith® speedROD (RP C18 column)	300 µL	Dipyridamole	LLE (using n-hexane and ethyl acetate)	2.7 minutes	20 µL
P Katakam.[20]	C18 column	300 µL	Donepezil-D7	LLE (using dichloromethane and hexane)	4 minutes	Not provided

LLE, liquid-liquid extraction; SPE, solid-phase extraction.