Use of Two Sulfonphthalein Dyes for the Sensitive and Selective Extraction-Free Spectrophotometric Assay of Albendazole in Bulk Drug and in Tablets

Table 1

Sensitivity and regression parameters.

Parameter	Method A	Method B
𝜆max, nm	445	460
Colour stability, min	90	60
Linear range, µg mL^−1	1.5–21.0	2.0–32.0
Molar absorptivity (𝜀), L mol^−1 cm^−1	1.27 × 10^4	7.57 × 10^3
Sandell sensitivity*, µg cm^−2	0.0209	0.0350
Limit of detection (LOD), µg mL^−1	0.01	0.16
Limit of quantification (LOQ), µg mL^−1	0.02	0.49
Regression equation, 𝑌**
Intercept (𝑎)	0.0358	0.0049
Slope (𝑏)	0.042	0.028
Standard deviation of 𝑎 (𝑆𝑎)	9.98 × 10^−2	9.98 × 10^−2
Standard deviation of 𝑏 (𝑆𝑏)	5.53 × 10^−3	3.39 × 10^−3
Regression coefficient (r)	0.9975	0.9997

∗Limit of determination as the weight in µg mL⁻¹ 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⁻¹, 𝑎 is intercept, and 𝑏 is slope.