Sample introduction with graphite furnace electrothermal vaporization into an inductively coupled plasma: effects of streaming conditions and gaseous phase additives

Abstract

A laboratory-made graphite furnace electrothermal vaporizer (GF-ETV) was applied with two alternative versions of the exit part. In one of the versions the vapor streams upward through the transverse hole of the longitudinally heated tube (upward streaming: UPS), while with the other version the vapor streams toward one of the ends of the tube (end-on streaming: ENS). Volatile (Cd, Zn) and medium volatile elements (Cu, Mg, Mn) were applied in multi-element solutions, in the mass range of 4–10 μg for each analyte. Net line intensities were compared for the two versions, and also for applying toluene or carbon tetrachloride vapor in the furnace atmosphere. Using pure argon as the internal furnace gas, the line intensities of the medium volatile elements Cu and Mg were lower for the ENS than for the UPS by approximately 40%. This was in agreement with findings of other authors for similar systems, and was explained by condensation of vapors on cooler parts of the graphite tube, close to the outlet end. On the other hand, the UPS and ENS provided similar line intensities for Cu and Mg when CCl 4 vapor (0.5% v/v) was used in the internal furnace gas as a result of the formation of volatile chlorides, which do not condense in the graphite tube. Recently published transport efficiency data, including our own results, are evaluated with respect of design characteristics, operating conditions, applied analytes and chemical modifiers/carriers.