High Magnetic Field Glow Discharge Ionization Source

摘要

We have modified our 'internal' electrospray source, which operates inside thehigh magnetic field associated with Fourier transform ion cyclotron resonance (fticr) mass spectrometry, to allow it to serve as a glow discharge (GD) ionization source. Figure 1 shows the overall experimental apparatus for this system, and Figure 2 is an expanded view of the modifications which make glow discharge possible. Quite reasonable ion signals are obtained with this source, in spite of the fact that the glow discharge ionization is taking place at a magnetic field of about 1.8 tesla. This corresponds to a field at least a factor of 25 higher than has ever been used with glow discharge sources before. One example of an analysis of the (60)Ni(+) signal in a NIST 661 stainless steel signal is shown in Figure 3. Signal-to-noise calculations for the top trace yield a limit of detection of 38 ppm for the peak at m/z 60. The predominant ion is (56)Fe(+), arising from the high concentration of iron in the steel.