Improved accuracy of rapid micro carbon and hydrogen method by modified combustion-absorption techniques

Abstract

The heat of reaction of carbon dioxide and water with their selective absorbents was found to seriously alter the buoyancy, or apparent weight, of the absorption tubes. This heat of reaction is effectively removed through modified tube packing techniques and a cooling fan, thus eliminating detrimental buoyancy changes and providing stable weighings of ±2 μg. A mixture of silver oxide-silver tungstate fused onto a diatomaceous earth support quantitatively retains the reaction products from interfering elements. This reagent follows a packing of magnesium oxide in the combustion tube at 800 °C and extends into a heating mortar at 80 °–170 °C. With fast combustion-sweep techniques, and an oxygen flow of 60–100 cc per minute, analyses are completed in 10 minutes. The absolute deviation for all types of compounds tested averaged ±0.03% for carbon and ±0.04% for hydrogen.