Ion-pair titrimetric assays of quetiapine fumarate in pharmaceuticals using sodium tetraphenylboron and sodium lauryl sulphate

Abstract

Two simple, rapid, precise and accurate titrimetric methods employing sodium tetraphenylboron (STPB) and sodium lauryl sulphate (SLS) as titrants are described for the quantitative determination of quetiapine fumarate (QTF) in bulk drug and tablets. The proposed methods are based on the solvent extraction-titration of QTF with STPB (method A) and SLS (method B) using tetrabromophenolphthalein ethyl ester (method A) and dimethyl yellow (method B) as indicators. In method A, the titration was performed in the presence of sodium acetate and 1, 2-dichloroethane whereas in method B, the titration was carried out in the presence of dilute sulphuric acid and dichloromethane. The methods were applicable over the ranges of 4.0-18.0 and 5.0-25.0 mg of QTF for method A and method B, respectively. The proposed methods yielded the reaction stoichiometries of 1:1 and 1:2 for method A and method B, respectively. The methods were applied successfully to the determination of QTF in tablets. The precision results, expressed by intra-day and inter-day relative standard deviation values, were satisfactory (RSD ≤1.56%). The accuracy was satisfactory as well (RE ≤2.2%). The percentage recoveries were in the range 97.37-104.1% with standard deviation values 0.47-1.26%.