Application of capillary zone electrophoresis to the analysis and to a stability study of nitrite and nitrate in saliva

The applicability of capillary zone electrophoresis for the determinations of nitrite and nitrate was studied. Using direct UV detection the limit of detection values of the analytes were 0.14 and 0.21 μg/mL, respectively. The developed method was found to be useful to directly determine nitrite, nitrate and thiocyanate in saliva. It was found that adjusting the pH of the sample to 11 and storing the saliva at 4 °C was adequate to make constant the nitrite/nitrate ratio in saliva samples at least 7 days.