Simple and Selective Spectrophotometric Determination of Ofloxacin in Pharmaceutical Formulations Using Two Sulphonphthalein Acid Dyes

Table 2

Sensitivity and regression parameters.

Parameter	Method A	Method B
𝜆max, nm	400	410
Linear range, μg/mL	1.0–16.0	1.0–16.0
Molar absorptivity (ε), L /mol/cm	2.40 × 10^4	1.96 × 10^4
Sandell’s sensitivity*, μg/cm^2	0.015	0.019
Limit of detection (LOD), μg/mL	0.11	0.09
Limit of quantification (LOQ), μg/mL	0.32	0.27
Regression equation, 𝑌^∗∗
Intercept (𝑎)	0.003	0.012
Slope (𝑏)	0.061	0.051
Standard deviation of 𝑎 (𝑆𝑎)	0.126	0.040
Standard deviation of 𝑏 (𝑆𝑏)	0.008	0.003
Regression coefficient (𝑟)	0.999	0.999

∗Limit of determination as the weight in μg per mL of solution, which corresponds to an absorbance of 𝐴 = 0.001 measured in a cuvette of cross-sectional area 1 cm² and 𝑙 = 1 cm. **𝑌=𝑎+𝑏𝑋, where 𝑌 is the absorbance, 𝑋 is concentration in μg/mL, 𝑎 is intercept, and 𝑏 is slope.