Atomic emission spectrometry with a reduced-pressure afterglow extracted from an inductively coupled plasma

Abstract

The inductively coupled plasma (ICP) has proven to be an excellent excitation source for elemental analysis of solutions by atomic emission spectrometry (AES). One reason for the success of the ICP is that volatilization and atomization interferences are minimal because the analyte is efficiently atomized in the high-temperature, atmospheric pressure environment. It seems that such an environment is essential for proper dissociation of analytes from sample particles such as those generated by solution nebulization. In a conventional ICP the analyte atoms then continue through the axial channel where they are excited and ionized at atmospheric pressure. In some ways, the observation of ICP emission at reduced pressure might offer potential advantages in that line widths should be sharper than from an atmospheric pressure source. The same experimental techniques for sampling the ICP for mass spectrometry (MS) should also be useful for AES at reduced pressures. In fact, in ICP-MS the initial extraction process is often accompanied by emission of visible radiation from inside the first vacuum chamber. In addition to potential analytical applications, the observation of emission spectra from such an afterglow could also provide fundamental information about processes occurring during the extraction step, which would be useful for furthermore » improvements in ICP-MS. In this communication the authors report for the first time the results of initial investigations that indicate the feasibility of using an analytical ICP at atmospheric pressure for atomization while observing atomic emission spectra at reduced pressure as the analyte species are extracted into a vacuum chamber.« less