Different Spectrophotometric Methods Manipulating Ratio Spectra Applied for the Analysis of Aclidinium in Duaklir^® Genuair^® Inhalation Powder

Table 1

Regression and validation of data for determination of aclidinium by the proposed ratio derivative and ratio subtraction methods.

Parameters		Ratio derivative	Ratio subtraction
Wavelength (nm)		229	238
Linearity range (μg/mL)		5─50
(i) Regression equation		y^a = bx^b + a	y^a = bx^b + a
(ii) Slope (b)		0.0380	0.0230
(iii) Intercept (a)		−0.0007	0.0032
Coefficient of determination (r^2)		0.9997	0.9996
LOD (μg/mL)		0.9681	1.1428
LOQ (μg/mL)		2.9336	3.4630
Accuracy (%R)^c		101.55	100.82
Precision (% RSD)^c	Repeatability	1.237	1.149
	Intermediate precision	1.707	1.520

y^a is the response of each method; x^b is the concentration of aclidinium in μg/mL in each method; ^cvalues for 3 determinations of 3 different concentrations.