Automated sampling system for the direct determination of trace amounts of heavy metals in gaseous hydrogen chloride by atomic absorption spectrometry

Abstract

An analytical procedure is described for the determination of iron, nickel, chromium and manganese in gaseous hydrogen chloride by means of a modified atomic absorption spectrometer. An automated sampling system allows a ‘quasi’ on-line monitoring of the investigated gas. The introduction of the gas was regulated by a magnetic valve, which is connected to the autoprobe of the spectrometer and to a control unit. Typical parameters, e.g., the temperature programme and the gas injection volume, were optimized. Different types of calibration were carried out using element standard solutions, standard additions of gaseous standards and standard solutions, as well as gaseous standards. The detection limit for the described procedure was 39 pg for iron, 8.7 pg for nickel, 1.1 pg for chromium and 0.4 pg for manganese (temperature = 25 °C) using the standard calibration with element standard solutions. The reproducibility of the absorbance signals for the elements in gaseous hydrogen chloride varies between 5.3 and 13%(n= 10).