Abstract: A back-titration method is proposed for the determination of alkaloids in the liquid extract and tincture of Ipecacuanha. The total alkaloids in the sample is precipitated by sodium tetraphenylboron in the acidic medium to form tetraphenylborate, and the excess reagent is then titrated with quaternary ammonium halide solution (Benzakonium chloride or alkyldimethylbenzylammonium bromide) using bromophenol blue as indicator. The method described above is simple, rapid, and accurate, which is suitable for the assay of Ipecac preparations. The reproducibility of this method is good and the results are in good agreement with of there official methods. Samples containing about 20 mg of total alkaloids were determined ten times with a standard deviation of ±0.69%. The determination may be completed within 1 hour.