Determination of sotalol by fluorescence quenching method

Sotalol has a weak fluorescence in aqueous solutions, so using a direct fluorescent method is difficult. The competitive reaction between sotalol and palmatine for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by spectrofluorimetry. CB[7] reacts with palmatine to form complexes with strong fluorescence. However, the presence of sotalol quenches the fluorescence intensity of the complexes. We attribute this to the competition between sotalol and palmatine for occupation of the CB[7] hydrophobic cavity. Results show that sotalol occupies the space within the CB[7] cavity, forcing palmatine molecules to reside in the aqueous environment. The quenching of the CB[7]/palmatine system is fast, and the degree of quenching is proportional to the concentration of sotalol. Therefore, a new and useful spectrofluorimetric method with high sensitivity and selectivity was developed for the determination of sotalol in aqueous solutions. The proposed method is fairly accurate, simple, rapid, reproducible, and sensitive. It is also specific for the identification of sotalol. Its detection limit is 0.033 mu g mL(-1). This paper also discusses the competition reaction mechanism between sotalol and palmatine in the CB[7] cavity.