Compatibility of Spatially Coded Apertures with a Miniature Mattauch-Herzog Mass Spectrograph

Abstract

In order to minimize losses in signal intensity often present in mass spectrometry miniaturization efforts, we recently applied the principles of spatially coded apertures to magnetic sector mass spectrometry, thereby achieving increases in signal intensity of greater than 10× with no loss in mass resolution Chen et al. (J. Am. Soc. Mass Spectrom. 26, 1633-1640, 2015), Russell et al. (J. Am. Soc. Mass Spectrom. 26, 248-256, 2015). In this work, we simulate theoretical compatibility and demonstrate preliminary experimental compatibility of the Mattauch-Herzog mass spectrograph geometry with spatial coding. For the simulation-based theoretical assessment, COMSOL Multiphysics finite element solvers were used to simulate electric and magnetic fields, and a custom particle tracing routine was written in C# that allowed for calculations of more than 15 million particle trajectory time steps per second. Preliminary experimental results demonstrating compatibility of spatial coding with the Mattauch-Herzog geometry were obtained using a commercial miniature mass spectrograph from OI Analytical/Xylem.

A Review of the Emerging Field of Underwater Mass Spectrometry

“…Over 10× increases in signal intensity were achieved, with no loss in mass resolution (Chen et al, 2015;Russell et al, 2015). Russell et al (2016) demonstrated that spatially coded apertures are compatible with a MHMS, hinting at possible applications to the IonCam system.…”

“…Recent work from Russell et al (2016) focused on applying spatial coding techniques to magnetic sector MS in order to reduce the dichotomy between resolution and sensitivity inherent to MS. Although such techniques were proposed for use in MS in 1970 (Eckhardt and Gross, 1970), they have only recently been demonstrated (Chen et al, 2015;Russell et al, 2015).…”

Improving the Performance of a Cycloidal Coded-Aperture Miniature Mass Spectrometer

“…The measurement matrix then contains off-diagonal elements representative of multiplexing and there is no longer a single set of detector elements for each m/z. After determination of the measurement matrix H from the physics and architecture of the system, a mass spectrum can be reconstructed from the coded spectrum for an unknown compound or compounds by solving the inverse problem S ̂= H −1 g, where S ̂represents an estimate of the real spectrum S. 11 Previous work demonstrated the ability of aperture coding to increase the throughput without sacrificing resolution in a 90°m agnetic sector mass analyzer, 21,23 a Mattauch−Herzog mass analyzer, 22 and a cycloidal mass analyzer, 20 all of which were coupled with a position sensitive array detector. For the 90°a nd Mattauch−Herzog instruments, a distorted image of the aperture is projected on the detector that varies for each m/z due to the physics and architecture of the mass analyzer.…”

“…Additionally, miniaturization of mass spectrometers must contend with a trade-off between throughput and resolution that limits performance relative to traditional, full-scale laboratory instruments . Most commonly used miniature mass spectrometers are based on ion trap, quadrupole, or time-of-flight mass analyzers. − Recently, there has been a renewed interest in miniature sector mass spectrometers due to the development of high-performance neodymium–iron–boron (Nd–Fe–B) permanent magnets that reduce the mass analyzer size and weight, and ion array detectors that offer simultaneous detection of ions over a wide mass range. − Furthermore, the use of spatially coded apertures can break the trade-off between throughput and resolution in a sector mass spectrometer and increase throughput without sacrificing resolution. ,− …”

“…Spatial aperture coding is a computational sensing technique that has been historically used in optical , and X-ray imaging and more recently in sector mass spectrometry. − In an analytical instrument like a sector mass spectrometer, the measurements, g , are related to the mass spectrum through the equation g = HS + n , where S is the input mass spectrum, n is noise, and H is the measurement matrix that incorporates the physics and architecture of the system and maps the input of the mass analyzer to the output of the mass analyzer at the detector. In a conventional sector mass spectrometer with a position-sensitive array detector, a narrow slit is used to define the position of ion input into the mass analyzer and make the measurement matrix an identity matrix .…”