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

Table 4

Repeatability studies.

Drug	Methods	Amount taken  [𝜇g/mL]	Amount found  [𝜇g/mL]	% Amount found  [𝑛=6]	Mean ± SD	% RSD
Tadalafil	A	20	20.15	100.75	100.75±1.06	1.06
	B	20	20.02	100.14	100.14±0.37	0.37
	C	40	40.30	100.76	100.76±0.86	0.85
	D	40	39.90	99.75	99.65±0.71	0.70

𝑛: number of estimations.