Effect of Pre-Analytical Conditions on Salivary Nitrite Levels

The aim of the present paper was to analyze the influence of sampling and storage procedures on nitrite con- centration values in the saliva of healthy persons. The samples were obtained and stored under varied condi- tions, and processed using the Griess method. Results: when the salivary nitrite concentration was measured immediately after collection a significant dependence on the collection time was observed. A mean value of 94 µmol/L (range 3 - 625) was obtained at 8:30 am. This value decreased significantly with time (p < 0.05) reaching a value of 68 at 12:30 noon. Concerning the sample storage, a significant increase in the nitrite concentration was observed after 2 hrs, either at 4?C or at room temperature (p < 0.05). In spite of the high variability between individuals the values for each individual showed a marked constancy independent of the sampling day. According to our results, by controlling pre-analytical parameters, principally sampling and storage procedures, reproducibility is improved.