The Use of Capacitive Transimpedance Amplifier Array Detectors for Mass Spectrometry

Abstract

Mass spectrometry is a powerful tool in the field of analytical chemistry. Though there have been numerous advances in mass analyzer technology over the decades, there has been comparatively little advancement in mass spectrometer detector technology. The development of the scientific charged-coupled device over 30 years ago brought the advantages of simultaneous detection over single channel detection to optical spectroscopy, including higher signal-to-noise ratios for a fixed analysis time, shorter analysis time to obtain a given signal-to-noise ratio, and greater sample throughput. While the use of array detectors to achieve simultaneous detection is commonplace in optical spectroscopy, ion detectors for mass spectrometry have lagged behind.Over the last decade, a new type of ion detector, the capacitive transimpedance amplifier (CTIA) array detector, has been developed that has a number of properties that make it an excellent tool for simultaneous detection using dispersive mass spectrometers. The CTIA array detector has high sensitivity as well as high gain stability, allowing it to excel in applications that require high precision measurements of ion signals, such as isotope ratio mass spectrometry.Capacitive transimpedance amplifier array detectors have previously been used to demonstrate the power of simultaneous detection on Mattauch-Herzog double focusing mass spectrometers, but the non-linear mass dispersion of these instruments means that the resolution is not constant across the array. A different type of dispersive instrument, the linear cycloid, has a linear mass dispersion, making it a good candidate for an array detector.The first detailed characterization of gain, read noise and dark-current noise, as well as of operating behavior over a range of temperatures, of the DM0025, a 1696 pixel CTIA array detector was performed.In addition, the first-ever combination of a CTIA array detector with a linear cycloid mass spectrometer was developed. This combined instrument demonstrated simultaneous detection of multiple masses, as well as a linear mass range. The results from the detailed characterization of the detector were used in conjunction with measurements of the performance of the combined instrument to suggest improvements for the next generation of linear cycloid instruments with CTIA array detectors.