was spiked by different
amounts of the standard solution of carvedilol followed by dilution
with buffer to the final concentration range of 15e300 ng mL1 for
the drug. Then, the extraction procedure was performed according
to the previous section. For each sample, fluorescence intensity of
extracted carvedilol in thin film at 340 nmwas subtracted from that
of the blank thin film. Calibration curvewas constructed by plotting
the corrected fluorescence intensity against the respective concentrations
of carvedilol. Linearity was evaluated by the leastsquares
regression method, which was used to calculate the slope
of the regression line, y-intercept and square of regression coefficient
(R2) values. Limits of detection (LOD) and quantification (LOQ)
values were calculated based on the standard deviation of the blank
response (s) and the slope (s) of carvedilol calibration curve according
to the following equations