Use of Charge Transfer Complexation Reactions for the Spectrophotometric Determination of Sumatriptan in Pharmaceuticals

Table 2

Regression and analytical parameters.

Parameter	DDQ method	I2 method
𝜆max, nm	585	375
Beer’s law limits (𝜇g mL^−1)	4.0–56.0	2.0–28.0
Molar absorptivity (L mol^−1 cm^−1)	4.77 × 10^3	9.56 × 10^3
Sandell sensitivity* (μg cm^−2)	0.0620	0.0309
Limit of detection (μg mL^−1)	0.77	0.17
Limit of quantification (μg mL^−1)	2.32	0.52
Regression equation, 𝑌^∗∗
Intercept, (𝑎)	−0.0104	0.0198
Slope, (𝐵)	0.0170	0.0295
Correlation coefficient (𝑟)	0.9997	0.9998
Standard deviation of intercept (𝑆𝑎)	0.00714	0.00499
Standard deviation of slope (𝑆𝑏)	0.00021	0.00029

*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, 𝑎 is the intercept, 𝑏 is the slope, and 𝑋 is the concentration in μg mL⁻¹.