Determination of inorganic anions in saliva by capillary isotachophoresis

Nitrite, nitrate, iodide and thiocyanate have been quantified in non-smoker and smoker saliva by capillary isotachophoresis (CITP). Hydrochloric acid (10 mmol l−1) adjusted with histidine to pH 6.0 plus 6% poly(vinylpyrrolidone) was used as the leading electrolyte (LE) and 5 mmol l−1 acetic acid as the terminating electrolyte (TE). Linearity was observed from 0.005 to 0.500 mmol l−1 with a coefficient of determination (r2) of 0.999. The separation of anions was achieved in less than 19 min. The minimal sample pretreatment and relatively low running cost make isotachophoresis good alternative to existing methods.