Characterization of an argon microwave plasma torch coupled to a Mattauch–Herzog geometry mass spectrometer

An atmospheric pressure argon microwave plasma torch (MPT) ionization source was coupled to a Mattauch–Herzog +mass spectrometer (MHMS) for elemental analysis. The operating conditions of the Ar MPT-MHMS were optimized for signal level, peak shape and resolution. The background spectrum was characterized, with most peaks arising from species that contain argon and nitrogen. Detection limits were in the tens to hundreds of pptr range while sensitivities are in the 106 counts s−1 ppm−1 regime for most elements. The major weakness of the Ar MPT-MHMS was isotope-ratio accuracy and precision.