Development and characterization of bottom-viewed inductively coupled plasma-atomic emission spectrometry

Abstract

In bottom-viewed inductively coupled plasma-atomic emission spectrometry (BV-ICP-AES), emission from the central channel of the plasma is measured axially from the bottom of the plasma. A straight quartz tube was used as a hollow light pipe (HLP) to collect plasma emission in this study. The HLP also serves as an injector for aerosols transport and injection into the ICP. The optical characteristics of HLPs with the original reflective surface and roughened outer surface are reported. The roughened HLP is effective in rejecting light beams that are not in line with the HLP. The transmission efficiency of the HLP, however, is high (> 70%) for light beams from a source that has the same dimension as the entrance of the HLP and is flush with the HLP. The HLP is effective in rejecting background emission from the core of the plasma that encircles the plasma central channel and yet efficient in light collection from the central channel of the plasma. The effects of central channel gas flow rate on atomic and ionic emission intensity of Sr and Zn are reported. Maximum intensity corresponds approximately to the minimum central channel gas flow rate for effective aerosol injection into the plasma. The emission intensity profiles also correlate with the thermal properties as well as excitation and ionization potentials of the test elements. BV-ICP may be a viable tool for the study of sample aerosol–plasma interactions, especially during the initial phase of the interaction when the sample aerosols first enter the plasma.