Specific and robust ion chromatographic determination of hypothiocyanite in saliva samples.

ABSTRACT

The enzymatic system in saliva, consisting of salivary peroxidase (SPO), hydrogen peroxide (H2O2), and thiocyanate (SCN-), produces hypothiocyanite (OSCN-) as a high effective antibacterial compound. OSCN- is of great importance for the natural non-specific antibacterial resistance in the oral cavity. However, no analytical method currently exists to selectively quantify OSCN- in saliva samples. A robust and specific analytical method for the determination of OSCN- was developed based on ion chromatography with combined UV and electrochemical detection. Calibration was achieved by calculating a derived calibration factor based on the known ratio of molar extinction coefficients of SCN- and OSCN-. Thus, the specific quantification of OSCN- in saliva samples is possible, as demonstrated here. The median value of 200 saliva samples was determined to be 0.56 mg L-1 (median), with a maximum of 3.9 mg L-1; the minimum value was below the detection limit (< 0.09 mg L-1). The recovery rate in individual saliva samples was 95 ± 8%.