Application of Atomic Absorption Spectroscopy to the Determination of Calcium in Saliva

Abstract

THE importance of salivary calcium concentration of the environment in the solubility of tooth and enamel is readily apparent. As with other biological fluids, numerous methods, ranging from classical oxalate–permanganate titration and emission flame photometry to the more recent complexometric and colorimetric techniques, have been used to estimate the calcium content of saliva. Unfortunately most of these methods have certain disadvantages. The oxalate–permanganate method requires relatively large amounts of saliva, time-consuming centrifugation, washing and titration within a narrow temperature-range. Its accuracy has been questioned because of incomplete precipitation of the oxalate or loss of some calcium oxalate during the washing process¹. Another devious procedure involves a complexometric analysis of calcium and magnesium in saliva followed by a separate colorimetric determination of magnesium, calcium being obtained as the difference². Several complexon-titration techniques using erio-chrome black T, murexide or plasmo corinth indicators were tested on saliva. They were found unsatisfactory because the colour shift at the end-point was either too gradual and indistinct or, in the case of murexide, the colour faded too rapidly.