Application of ion-pairs in pharmaceutical analysis, atomic absorption spectrometric determination of promazine, chlorpromazine, promethazine, imipramine and ciprofloxacin hydrochlorides with sodium cobaltinitrite

Ion-association complexes of promazine HCl (I), chlorpromazine HCl (II), promethazine HCl(III), imipramine HCl (IV) and ciprofloxacin HCl (V) with [Co(NO2)(o)](3-) were precipitated at their optimum conditions of pH and ionic strength (NaCl-HCl/NaOH) and the excess unreacted cobalt complex was determined using atomic absorption spectrometry (AAS). The applicability of the method for determination of the above drugs in pure solution, pharmaceutical preparations and urine was examined. The drugs can be determined in the ranges 0.485-4.854, 1.619-16.197, 1.441-14.410, 1.415-14.154 and 0.578-5.787 mg/25 ml of I, II, III, IV and V, respectively, with mean relative standard deviations 1.05-1.53% and recovery values of 98.85+/-0.31-100.09+/-0.54% indicating high precision and accuracy. The sensitivities of the proposed method were 11.73, 23.00, 30.00, 38.00 and 12.69 mu g/ml for the drugs I, II, III, IV and V, respectively; and the detection limits for determination of the investigated drugs were 3.10, 7.20, 13.80, 18.30 and 6.63 mu g/ml for I, II, III, IV and V, respectively. The suggested method has been applied for the determination of the above mentioned drugs in their pharmaceutical formulations and urine.