A low-flow low-power helium microwave induced plasma for optical and mass spectrometry with solution nebulization

Abstract

A low-flow low-power annular-shaped microwave induced helium plasma operating at atmospheric pressure has been developed for use in optical emission as well as mass spectrometry. The first study on the plasma formation and fundamental investigation of the plasma generated at helium flow rate below 3 L min⁻¹ by the new TEM cavity based MIP system is described. Radial profiles of emission spectra provide He excitation temperature (T_exc) of 3000–3300K and electron number density (n_e) of 5.5–7.5 × 10¹⁴ cm⁻³. To demonstrate the plasma robustness, both the tolerance for water loading and the excitation capability for metals and nonmetals were investigated using ultrasonic nebulization for wet aerosol introduction into the plasma. Detection limits data are shown for some elements and compared with those obtained using other MIP systems.