| Plasma source mass spectrometry (PSMS) is a standard method for elemental analysis for numerous reasons, such as high sensitivity, the availability of isotopic information, and its amenability to most elements. If all ions are detected simultaneously, the technique is improved: analyses can be accomplished quicker with less sample consumption, noise sources can be eliminated, and transient signals can be accurately recorded. Unfortunately, the technology to continuously and simultaneously detect a complete mass spectrum is antiquated, so the aforementioned benefits cannot be fully realized. Several MS geometries, such as time-of-flight (TOF-MS) and ion trap (IT-MS) approximate simultaneous detection with simultaneous extraction. These instruments, though, cannot take full advantage of simultaneous detection due to a low duty cycle, since they are inherently pulsed. Other instruments utilize multiple detectors to simultaneously detect several m/z values. It is impractical, though, to detect a complete mass spectrum with this technology. To address this need in PSMS, a new, completely electronic detector array has been developed and tested at Indiana University and implemented in a Mattauch-Herzog geometry mass spectrograph (MHMS). In its current state of development, the detector, termed the focal plane camera (FPC), allows for the simultaneous detection of up to 16 m/z values. Although the FPC is still a prototype, its performance has proven to be comparable to or better than the state-of-the-art single-channel mass spectrometry detectors, secondary electron multipliers (SEM). With the MHMS-FPC and an inductively coupled plasma (ICP) ionization source, detection limits are in the parts-per-quadrillion (ppq) regime and isotope ratio precision is better than 0.01%. Additionally, the FPC does not exhibit the mass-dependant detection efficiency that plagues SEM detectors. Figures of merit this promising have led to the coupling of sample introduction methods such as gas and liquid chromatography to the ICP-MHMS-FPC to create a powerful tool for speciation analysis. |
