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Table 1 Quantitative parameters for methods A-C.

From: Spectrophotometric determination of etodolac in pure form and pharmaceutical formulations

Parameter A B C
λmax, nm 510 521 726
Beer's conc. Range (μg mL-1) 0.5–8.0 1.0–10 2.0–18
Ringbom conc. Range (μg mL-1) 0.85–7.5 2.0–8.5 3.0–16.5
Detection limits (μg mL-1) 0.065 0.104 0.228
Quantification limit (μg mL-1) 0.217 0.347 0.76
Molar absorpitivity × 10 4(L mol-1 cm-1) 1.812 1.876 1.039
Sandell sensitivity (ng cm-2) 15.86 15.32 27.66
Regression equation a    
S y/x 0.202 0.285 0.246
Intercept 0.0078 - 0.0018 0.0011
S a 0.142 0.201 0.2007
± tSa 0.365 0.517 0.516
Slope 0.0582 0.066 0.036
S b 0.0285 0.0365 0.018
± tSb 0.0733 0.094 0.0462
Correlation coefficient (r) 0.9999 0.9999 0.9997
Mean ± SD% 99.87 ± 0.659 100.21 ± 0.727 99.875 ± 0.759
RSD% 0.66 0.73 0.76
Variance 0.434 0.528 0.576
SE 0.269 0.297 0.31
Student, s t-valueb (2.571) 1.16 0.323 1.07
Variance ratio F-test b (6.256) 1.06 1.29 1.406
  1. a A = a + b c, where c is the concentration in μg mL-1.
  2. b The theoretical t- and F-values, 2.571 and 6.256, respectively for five degree of freedom at 95% confidence level.