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

Abstract

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.

Application of a nitrogen microwave-induced plasma mass spectrometer as an element-specific detector for arsenic speciation analysis

“…microwave power is necessary for elements with high ionization potentials. 26,27 For elements with high ionization potentials such as As (9.8 eV), the intensity is enhanced on increasing the forward microwave power, 26 which agrees with our experimental ®ndings. The annular-shaped plasma is in¯uenced by the microwave power.…”

“…As the counts increase with increasing power, further increase in power may increase the concentration of 75 As z in the plasma. 18,19,26 It is desirable for the power to be as high as possible to increase the sensitivity. Hence, further work will be directed towards lowering the detection limits of arsenic compounds by increasing the microwave power.…”

“…A further increase/ decrease results in a decrease in total counts, as has been observed previously for total arsenic determination. 15,26 It should be noted that the maximum ion signal value may be obtained as a compromise between the increment of aerosol into the plasma and the decrease of temperature in the central part of the plasma. This is recognized by the observation of a change in the color of the central part of the plasma with an increase in the nebulizer gas ¯ow rate.…”

Gas chromatography combined with fast flow glow discharge mass spectrometry (GC-FFGD-MS)

“…Plasma-based detectors for gas chromatography have focused on ICP [6][7][8][9][10] and MIP [11][12][13][14][15] sources, with GD plasmas playing a minor role, although Harley and Pretorius 16 reported the first use of a glow discharge as a detector for gas chromatography in 1956. They observed the voltage change across an argon discharge and used this to detect hydrocarbons.…”

Fundamental studies of the plasma extraction and ion beam formation processes in inductively coupled plasma mass spectrometry

“…One of the main development has been the use of MIP as a detector for gas chromatography (205)(206)(207). Microwave plasmas have been investigated for mass spectrometry with support gas with Ar (18,19,208), nitrogen (209)(210)(211), and helium (142,212,213).…”