A SEALED TUBE DRY COMBUSTION METHOD FOR ULTRAMICRODETERMINATION OF FLUORINE IN ORGANIC-COMPOUNDS

A sealed tube dry combustion method has been applied to ultramicrodetermination of fluorine in organic compounds. A sample below 1 mg is weighed in a thin quartz glass tube with one end closed and a small amount of sodium carbonate is placed in the same tube. Oxygen is then slowly blown into the tube and the open end is closed, forming a fine tip. The sealed tube is heated at 580 °C in an electric furnace for 1.5 h to decompose the sample. Inorganic fluorine reacts with sodium carbonate and the resultant fluoride is dissolved in an aqueous solution introduced in the sealed tube after breaking off of the fine tip. The fluoride ion is determined spectrophotometrically using lanthanum-alizarin complexone. © 1991.