Homogeneity and stability studies on sodium, calcium, magnesium, and manganese in human saliva

This article reports on the homogeneity and stability of saliva samples treated and stored under different conditions. The analytes chosen for this evaluation were Na, Ca, and Mg as minor elements and Mn as the trace element. The results obtained show that when the sample was homogenized in an ultrasonic bath, a minimum volume of 0.25 mL was required to consider the sample homogeneous. The stability of the analytes depended on their concentration. The Ca and Mg content seemed to be stable for at least 1 wk when the samples were stored at room temperature, whereas the Mn content seemed to be unstable for 1 d even when the sample was stored at -20 degreesC.