Investigation of the pindolol-Fe(III) complex and its use in the spectrophotometric determination of pindolol in bulk drug and tablets.

ABSTRACT

It was found that pindolol reacts with Fe(III) chloride producing a green water soluble complex (11, v/v) with maximum absorbance at 635 nm. By applying the methods of Sommer and Job [Sommer et al., Folia, tomus XI, Chemia 7, 25, 1970] the conditional stability constant of the complex at pH = 1.70 +/- 0.02 was found to be log K' = 4.95 and the molar absorptivity of the complex to be 206 l mol-1 cm-1. Beer's law was obeyed up to a concentration of 220 mumol l-1 of pindolol. The recoveries were 98-101% (n = 7) and the detection limit was 5 micrograms ml-1. The described method was sufficiently simple, selective and sensitive to be suitable for the rapid and accurate determination of pindolol in tablets.