Sensitive high-performance liquid chromatographic assay for the determination of chlorhexidine in saliva

A high-performance liquid chromatographic assay was developed to determine salivary chlorhexidine concentration. Saliva sample (200 μl) was extracted into methylene chloride. Chromatographic separation was achieved with a C₁₈ column using a mobile phase of acetonitrile-0.05 M sodium acetate and 0.005 M heptanesulfonic acid (40:60, v/v). The standard curve was linear from 0.051 to 20.48 μg/ml (r² ≥ 0.997). Intra-day and inter-day coefficients of variation were <5.5 and ≤9%, respectively. The assay is rapid, sensitive, simple, and successfully used for quantitating salivary chlorhexidine content released from a chlorhexidine-impregnated resin worn by patients.