title: Investigation of penbutolol-iron (III) complex and its spectrophotometric determination in tablets.
abstract: 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.
authors.affiliation: Institute of Pharmaceutical Chemistry, Faculty of Pharmacy, Belgrade, Yugoslavia.
authors.forename: D
authors.initials: D
authors.lastname: Radulović
authors.forename: D
authors.initials: D
authors.lastname: Pećanac
authors.forename: L
authors.initials: L
authors.lastname: Zivanović
authors.forename: S
authors.initials: S
authors.lastname: Agatonović-Kustrin
mesh_terms: D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007501:Iron / Q000032:analysis*; D010394:Penbutolol / Q000032:analysis*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets; D013861:Thiocyanates
chemical_list: D007202:Indicators and Reagents; D012996:Solutions; D013607:Tablets; D013861:Thiocyanates; D010394:Penbutolol; C026976:thiocyanic acid; D007501:Iron