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.