Item Brimonidine Tartrate Timolol Maleate
Linear range (μg/ml) 4-24 10-60
Detection limit (μg/ml) 0.05 0.09
Quantitation limit (μg/ml) 0.15 0.29
Regression data    
No. 5 5
slope (b) 42167 22395
Standard deviation of the slope 56.36 36.67
intercept (a) 4937 8914
Standard deviation of the intercept 637.86 641.36
correlation coefficient® 0.9999 0.9998
Standard error of regression 0.09 0.3
(Y = a + bC, where C is the concentration of the compound (μg/ml) and Y is the drug peak area)
Table 2: Calibration data was resulted from method validation of Brimonidine Tartrate and Timolol Maleate respectively.