Dissolution of Samples by Heating with a Microwave Oven in a Teflon Vessel for Instrumental Analyses

Abstract

The Bureau of Mines developed a method for rapidly dissolving ores, slags, furnace products, and ashes for atomic absorption and other instrumental analyses. The method makes use of a microwave oven for heating the sample in a uniquely designed, commercially available Teflon (fluorocarbon polymer) vessel which is able to withstand the heat and pressure of the reactions. The inert quality of Teflon allows the use of various acid combinations and strong acid concentrations as dissolving solutions. Samples prepared using this method can be analyzed for elements at major, minor, and trace levels of concentration from a single solution. These elements include Si, Al, Ca, Mg, Fe, Cu, Mn, Ni, Co, Na, K, etc., with accuracy equal to or better than other conventional dissolution methods.The method is relatively inexpensive because of the durability of the vessel (more than 75 dissolutions) and the number of possible assays per sample: it requires about 20 ml of acid per sample; heating time is about 10 s per sample.