Estimation of Tadalafil Using Derivative Spectrophotometry in Bulk Material and in Pharmaceutical Formulation

Table 3

Precision studies.

Drug	Methods	Concentration  [𝜇g/mL]	Intra-day  [𝑛=3]	% RSD	Inter-day  [𝑛=3]	% RSD
Tadalafil	A	10	9.93	0.32	9.95	0.31
		20	20.20	0.77	20.25	1.17
		40	40.71	0.10	40.66	0.07
	B	10	9.87	0.67	9.90	0.40
		20	20.03	0.06	20.05	0.13
		40	40.07	0.06	40.17	0.14
	C	30	30.08	0.12	30.33	1.32
		40	40.12	0.11	40.07	0.08
		60	60.07	0.07	60.11	0.11
	D	30	29.73	1.69	30.02	1.30
		40	39.91	0.94	39.68	1.41
		60	59.48	1.03	59.93	1.11

𝑛: number of estimations.