LESSENING UNEXPECTED INCREASES OF ATOMIC VAPOR TEMPERATURE OF ARSENIC IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

It was found that the atomic vapor temperature of Se increased unusually in the analysis of Se added with Pd as the matrix modifier. To make an advanced study on this phenomena, and to lessen the interference, the (effective) atomic vapor temperature of As was measured by the two-absorption line method, and its relation to matrix modifiers was studied by using a multi-channel atomic absorption spectrometer. The atomic vapor temperature of As was measured by referring to the atomic vapor temperature of Pb in the furnace. The results are discussed along with the phase diagrams of As-alloys. In the presence of Cu or Co, it was presumed that As was atomized before formation of intermetallic compounds. In the presence of Pd or Ni, atomization of As began near the melting point of intermetallic compounds. An unexpectedly higher temperature of As atomic vapor was observed in the case of the rapid atomization. The atomic vapor temperature rose higher than one would have expected. Addition of potassium permanganate effectively reduced the unexpected temperature increase, and allowed a clear absorbance profile of atomization for As analysis of urine to be obtained.