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

The enzymatic system in saliva, consisting of salivary peroxidase (SPO), hydrogen peroxide (HO), 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 (median), with a maximum of 3.9 mg L; the minimum value was below the detection limit (< 0.09 mg L). The recovery rate in individual saliva samples was 95 ± 8%.