Conductometric titrations of chlorhexidine and proguanil are reported. The procedure is based on the copper-bi-guanide reaction which gives a pink solid. Studies at several pH values, and presence of NH3 and ethanol are carried out. 3 ml of 0.2 M NH3, 9ml of 0.01 M NaOH diluted to 60 mL with 15% ethanol are added to 5ml of biguenide aqueous solution and titrated awith cooper acetate. Concentrations of Chlorhexidine in 5.9x10-5 - 3.4x10-4 M range are determined. Fareignspecies presence is studied too. Biguanides are found in several pharmaceutical formulations and industrial samples. Estimetion of chlorhexidine and proguanil salts with the standard method lacks selectivity since it is based on perchloric acid titration in acetic acid medium1. Some recent papers about determination of chlorhexidine and proguanil have been publisghed: potentiometric titration of chlorhexidine2 polarographic determinetion of praguanil and chlorhexidine3,4 spectrophotometric assay of chlorhexidine in contact lens solutions5 and suppositories6, HPLC of proguanil in serum sam-ples7 and chlorhexidine in several samples 8,9,10,10,11 or G C 12,13 and mass fragmentography14,15.
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