Spectrophotometric and potentiometric determination of some pharmaceutical compounds in its formulations and biological samples

The aim of this work is to develop new spectrophotometric andpotentiometric methods for the determination of micro amounts of differentpharmaceutical compounds such as citalopram hydrobromide (CTP) andtadalafil (TDF) in pharmaceutical preparations and biological samples.The spectrophotometric methods in the present investigation include:ion-pair technique which is based on the formation of yellow ion-paircomplexes between the basic nitrogen of the drug and four sulphonphthaleinacid dyes, namely; bromocresol green (BCG), bromothymol blue (BTB) ,bromocresol purple (BCP) and bromophenol blue (BPB) in acetate buffer. Theformed complexes were extracted with chloroform, and oxidation-reductiontechnique which is based on the oxidation of the studied drugs by a knownexcess of potassium permanganate in acidic medium and estimation theunreacted permanganate with amaranth dye (AM), indigocarmine (Indigo) andmethylene blue (MB).The proposed methods are successfully applied to determine the studieddrugs in the pure and in their dosage forms. The results obtained are comparedstatistically by Student’s Hest (for accuracy) and variance ratio F-test (forprecision) with the official methods at 95 % confidence level. The resultsshowed that the t- and F- values are less than the critical tabulated valueindicating that there is no significant difference between the proposed andofficial methods. Thus the proposed spectrophotometric and potentiometricmethods can applied in routine analysis for determination of the studied drugsin pure and in dosage forms.