Mechanism of atomic vapor loss for aluminum and potassium in a constant-temperature carbon-tube furnace

Deviations from a simple diffusion law of analyte vapor loss are easily studied in the Woodriff constant temperature furnace, in which an isothermal, heated carbon tube encloses the vapor. A considerable deviation from a general diffusion law is observed for Al and potassium when a graphite tube serves as the "cuvette". Apparently analyte atoms form compounds with the heated graphite tube wall and then are released again as atoms to continue diffusing toward the ends of the tube. This process is not evident in a glassy C tube in which analyte vapor loss closely follows a simple diffusion law. The loss rate of atomic vapor in the glassy C tube is faster than that in the graphite tube but the analytical sensitivity--based on the peak atomic absorbance--is better in the glassy C tube. 23 ref.--AA.