SEQUENTIAL FLOW-INJECTION DETERMINATION OF IONIC AND TOTAL CALCIUM INSALIVA

In this paper a flow injection manifold for the sequential determinati on of ionic and total calcium in a small (75 mu L) sample of saliva is presented. This setup incorporates two detectors, a tubular potentiom etric detector and an atomic absorption spectrophotometer, for determi ning the ionic and total calcium, respectively. Furthermore, the saliv a samples can be injected directly into the manifold without any pre-t reatment or loss of carbon dioxide. The results of the analyses of 20 saliva samples were in good agreement with those obtained by the two r eference procedures, the direct potentiometry for ionic calcium and at omic absorption spectroscopy for total calcium. The paired Student's t -test showed that there were no statistical differences in the results obtained. The relative standard deviations of ten consecutive measure ments of the same salive sample were approximately 3% for ionic calciu m and 4% for total calcium. Effects of differences in coexisting ions, ionic strength, and pH between standard solutions and samples were ne gligible.