Parameters GMF MXF Method A Method B Method C Method A Method B Method C λ max (nm) 510 528 610 510 528 610 Beer’s law limits, µg mL-1 0.1-2.0 0.1-2.0 0.2-4.8 0.2-2.4 0.2-4.0 0.2-2.6 Ringboom limits, µg mL-1 0.3-1.8 0.3-1.8 0.5-4.0 0.4-2.0 0.5-3.6 0.4-2.2 Molar absorptivity, x 105 L mol-1 cm-1 8.25 10.31 6.49 7.17 7.79 10.66 Sandell sensitivity, ng cm-2 5.88 4.71 7.48 6.11 5.62 4.12 Regression equationa Intercept (a) - 0.002 0.0008 0.0045 - 0.0016 0.0004 - 0.0085 Standard deviation of intercept (Sa) 0.0055 0.0058 0.0079 0.0067 0.0091 0.0074 Slope (b) 0.1757 0.213 0.1276 0.1669 0.1759 0.2601 Standard deviation of slope (Sb) 0.0054 0.0087 0.0094 0.0090 0.0098 0.0086 Correlation coefficient, (r) 0.9997 0.9998 0.9995 0.9997 0.9998 0.9994 Mean ± SD 100.03 ± 0.844 100.18 ± 0.96 100.28 ± 0.76 99.44 ± 1.49 99.90 ± 1.04 99.45 ± 1.15 RSD% 0.844 0.96 0.76 1.50 1.04 1.16 RE% 0.886 1.01 0.80 1.57 1.09 1.21 Limit of detection, µg mL-1 0.026 0.029 0.058 0.059 0.055 0.056 Limit of quantification, µg mL-1 0.087 0.097 0.193 0.197 0.183 0.187 Calculated t-valueb 0.13 0.39 0.64 0.65 0.07 0.76 Calculated F-valueb 1.06 1.37 1.16 2.99 1.46 1.78
aA = a + bC, where C is the concentration in μg mL-1, A is the absorbance units, a is the intercept, b is the slope.
bThe theoretical values of t and F are 2.57 and 5.05, respectively at confidence limit at 95% confidence level and five degrees of freedom (p=0.05).
Table 1: Analytical and regression parameters of spectrophotometric methods.