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Table 1 Analytical performance data of the calibration graphs for the determination of benzophenone by the proposed methods

From: Derivative spectrophotometric analysis of benzophenone (as an impurity) in phenytoin

Parameter First derivative method (1D) Third derivative method (3D) Ratio derivative method (1DD)
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, Sy/x 4.77 × 10-3 5.14 × 10-3 0.21
Standard deviation of the intercept, Sa 3.71 × 10-3 3.99 × 10-3 0.16
Standard deviation of the slope, Sb 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 A1% (dl.g-1.cm-1)a 2655 1181 9.24 × 104
D ε (L.mol-1.cm-1)b 4.83 × 104 2.15 × 104 1.68 × 107
  1. a Specific absorbance of the derivative mode.
  2. b Molar absorptivity of the derivative mode.