Effect of different sample preparation methods on the atomic-absorption spectrophotometric determination of calcium in plant material

Abstract

A study is reported showing the variability in the figures for calcium content obtained on certified standard reference plant material that had been subjected to five different methods of digestion. The results show that some methods of preparation resulted in inaccurate calcium contents. Choice of acids and methods for digesting the plant material to the stage where calcium can be extracted into dilute nitric acid, time and concentration of releasing agents (lanthanum and strontium) significantly affected the calcium results. The use of a dinitrogen oxide-acetylene flame or additional dilutions so that the calcium content of the solution was approximately 1–5 p.p.m. usually gave acceptable results.