Sensitive and Selective Spectrophotometric Determination of Gabapentin in Capsules Using Two Nitrophenols as Chromogenic Agents

Table 3

Regression and analytical parameters.

Parameter	Method A	Method B
λ max, nm	415	420
Beer’s law limits (μg mL^−1)	1.25−15	2−18
Molar absorptivity (l mol^−1 cm^−1)	1.09 × 10^4	0.64 × 10^4
Sandell sensitivity* (μg cm^-2)	0.0158	0.0267
Limit of detection (μg mL^−1)	0.23	0.75
Limit of quantification (μg mL^−1)	0.71	2.28
Regression equation, Y**=	0.0072 + 0.062X	0.0094 + 0.035X
Correlation coefficient (r)	0.9993	0.9994
Standard deviation of intercept (Sa)	0.0229	0.0276
Standard deviation of slope (Sb)	0.0025	0.0026

*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.