From: Derivative spectrophotometric analysis of benzophenone (as an impurity) in phenytoin
Parameter | First derivative method (^{1}D) | Third derivative method (^{3}D) | Ratio derivative method (^{1}DD) |
---|---|---|---|
Wavelength λ (nm) | 257.6 | 263.2 | 272 |
Concentration range (μg/mL) | 1-10 | 1-10 | 1-10 |
Intercept (a) | 20.65 × 10^{-3} | 1.98 × 10^{-3} | -0.67 |
Slope (b) | 0.27 | 0.12 | 9.24 |
Correlation coefficient (r) | 0.9999 | 0.9999 | 0.9999 |
Standard deviation of the residuals, S_{y/x} | 4.77 × 10^{-3} | 5.14 × 10^{-3} | 0.21 |
Standard deviation of the intercept, S_{a} | 3.71 × 10^{-3} | 3.99 × 10^{-3} | 0.16 |
Standard deviation of the slope, S_{b} | 0.61 × 10^{-3} | 0.66 × 10^{-3} | 0.02 |
Relative standard deviation, % RSD | 0.83 | 1.10 | 0.97 |
Percentage error, % Error | 0.34 | 0.45 | 0.39 |
Limit of detection (LOD) (μg/mL) | 0.04 | 0.11 | 0.06 |
Limit of quantitation (LOQ) (μg/mL) | 0.13 | 0.34 | 0.18 |
D A^{1%} (dl.g^{-1}.cm^{-1})^{a} | 2655 | 1181 | 9.24 × 10^{4} |
D ε (L.mol^{-1}.cm^{-1})^{b} | 4.83 × 10^{4} | 2.15 × 10^{4} | 1.68 × 10^{7} |