Assay of Sodium Rabeprazole Enteric Tablets by Indirect Argentimetry

A definite amount of the drug tablets was weighed,pulverized and dissolved in ethanol. The solution was filtered and made up to 100 mL in a brown colored volumetric flask and kept in a refrigerator. An aliquot of the sample solution was taken and reacted in an amoniacal solution of pH 8~9,with a definite amount of standard AgNO3 solution,heated at 50 ℃ in a water bath for 20 min. During the reaction,the Na+-ion attached to nitrogen atom of the imidazole ring of the drug molecule was replaced by Ag+-ion quantitatively forming an insoluble silver salt with the drug. After filtering,the filtrate was titrated with standard NH4SCN solution at pH 4~5,with ferric ion as indicator. Content of sodium rabeprazole in the drug was calculated indirectly from the amount of titrant used. Precision of the proposed method was tested,giving value of RSD′s (n=5) of 0.9%. Recovery of the method was also tested by standard addition method,giving values of recovery in the range of 98%-102%.