A comparative investigation of some analytical performance characteristics of an inductively-coupled radio frequency plasma and a capacitively-coupled microwave plasma for solution analysis by emission spectrometry

Abstract

This paper reports results of an inter-laboratory investigation involving standardized experiments performed with standard measuring equipment to establish unambiguously the differences in analytical performance of an inductively-coupled radio frequency plasma (ICP) and a capacitively-coupled microwave plasma (CMP) for simultaneous multi-element analysis (SMEA) of solutions. The authors compared a laboratory-built, prototype ICP and a standard commercial CMP. The analytical characteristics covered were the following: (i) detection limits, (ii) matrix effects produced by cesium sulfate, cadmium sulfate, and di-amnioniumhydrogenphosphate, (iii) sensitivities, and (iv) precision. These characteristics were evaluated for 14 spectral lines of 12 representative elements. The results were corrected for differences in the performance (aerosol injection rate into the plasma) of the nebulizers used with the two excitation sources and for differences in transmission factor, optical conductance and photomultiplier responsivity between the two “identical” measuring equipments. It was definitively established that in all respects the ICP (investigated here) is superior to the CMP (considered here) as an excitation source for SMEA of solutions.