A Moderate-Power Nitrogen Microwave-Induced Plasma as an Alternative Ion Source for Mass Spectrometry

The moderate-power nitrogen plasma is evaluated as an alternative ion source for plasma mass spectrometry. The nitrogen MIP-MS exhibits linear dynamic ranges of about 3-4 orders of magnitude and low ppb to sub-ppb detection limits for most elements under multielement scanning conditions. Nitrogen MIP-MS is capable of determining K, Ca, Cr, As, and Se at their major isotopes. In addition, nitrogen MIP-MS provides lower detection limits than argon ICP-MS for K (0.48 ppb) and Ca (0.24 ppb). The nitrogen MIP-MS system allows the determination of isotope ratios for 10 ppm of Ca (40/44) and 100 ppb of K (39/41), Cr (52/53), and Se (80/78) with less than 5% error.