2.5. Procedures
2.5.1. Preparation of calibration curve
Into a series of 10 ml calibration flasks, aliquots of standard
drug solution (0.2–6 ml of 10 lg ml1
) equivalent to 0.2–
6.0 lg ml1 STS were accurately transferred and the volume
wwas made up to the mark with the solvent (0.1 M HCl in method
A; acetonitrile in method B). The absorbance of each solution
was then measured at 226 nm in method A and 228 nm in
method B, against the respective solvent.
In either case, calibration curve was prepared by plotting
the absorbance versus concentration of drug. The concentration
of the unknown was read from the respective calibration
curve or computed from the regression equation derived using
the Beer’s law data.