Low-temperature oxygen-fluorine radiofrequency ashing of biological materials in poly(tetrafluoroethylene) dishes prior to the determination of tin, iron, lead and chromium by atomic-absorption spectroscopy

Abstract

Low-temperature radiofrequency ashing utilising plasma-excited oxygen alone requires long ashing times and for this reason has not been generally accepted. In this paper it is shown how ashing time can be reduced considerably by introducing fluorine into the oxygen plasma and a novel and efficient method of achieving this is described. Food products and National Bureau of Standards Standard Reference Materials, both of known trace metal content, are prepared by the method described. Analysis of the ash by atomic-absorption spectroscopy shows good recovery of added tin and agreement with certified values for iron, lead and chromium.