Determination of antibacterial quaternary ammonium compound in lozenges and human serum by resonance light scattering technique

A method for the specific determination of an antibacterial quaternary ammonium compound Dequalinium. chloride (DQC) was described in this paper. At pH 0.5, the resonance light scattering (RLS) intensity of sodium dodecyl benzene sulfonate (SDBS) remarkably was enhanced by adding DQC. A RLS peak at 392.0 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DQC in the range of 0.096-2.88 mu g/mL. The detection limit was 2.98 ng/mL and the correlation coefficient was r = 0.9988 (n = 9). The method was applied to the analysis of DQC in lozenges and human serum. The results indicated that the method was sensitive, simple, practical and useful in the clinical assay. (C) 2008 Elsevier B.V. All rights reserved.