Investigation of penbutolol—iron(III) complex and its spectrophotometric determination in tablets Academic Article uri icon


  • It has been established that penbutolol reacts with iron(III) chloride in the presence of ammonium thiocyanate to form a pink complex (2:1) that is soluble in chloroform with a maximum absorbance at 478 nm. By application of the methods of Sommer and Job involving non-equimolar solutions, the conditional stability constant (log k') of the complex at the optimum pH of 1.5 +/- 0.02 and an ionic strength of (mu) 0.14 M, was found to be 5.769. The molar absorptivity at 478 nm was 136 1 mol-1 cm-1 at pH 1.5 +/- 0.02. The validity of Beer's law has been tested in the concentration range 3-18 x 10(-4) M; the relative standard deviation (n = 8) was 1.52-3.21%. The proposed method was found to be suitable for the accurate, simple and rapid analysis of penbutolol in the bulk drug and in tablets.


  • Kustrin, Snezana
  • Radulović, D
  • Pećanac, D
  • Živanović, Lj
  • Agatonović-Kuštrin, S

publication date

  • January 1990