HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC (HPLC) ASSAY FOR THE DETERMINATION OF CHLORHEXIDINE IN SALIVA FILM

An HPLC assay for the determination of chlorhexidine in small samples (<1 mu l) of saliva is described, A base deactivated reverse phase C-1 8 narrow bore column (ODS-B Exsil) was used for the analysis. Saliva s amples were collected on Periopaper strips and chlorhexidine was extra cted with 0.1 ml mobile phase. The optimal mobile phase comprised 55 % v/v acetonitrile, 0.2 %v/v glacial acetic acid, 7 mM sodium laurylsulp hate and column temperature was maintained at 55 degrees C. Benzethoni um was included as the internal standard and a dual wavelength UV abso rbance detector was used to analyse chlorhexidine at 254 nm and benzet honium at 275 ma Triplicate standard curves were linear for the range of concentration 1 to 15 ng/sample (R(2) > 0.99). if 0.5 mu l of saliv a is collected then 2 to 30 mu g/ml chlorhexidine can be measured. The intra-assay variability, determined from repeated injections of quali ty control standards containing 1, 3.75 and 12.5 ng chlorhexidine/tube was 12.9, 4.4 and 1.5% respectively.