A Mini Mass Spectrometer with A Low Noise Faraday Detector

An ion trap mass spectrometer is conventionally equipped with an electron multiplier as its detector. However, the electron multiplier can typically work at pressures below 20 mTorr with a high voltage applied, which limits the further miniaturization of ion trap mass spectrometers. As one of our continuous efforts towards the development of smaller mass spectrometers, a low noise faraday detector was developed and integrated in our miniature mass spectrometer instrument. A post data reconstruction method was also applied to counterbalance the peak broadening effect from the limited bandwidth of the detection circuit. A limit of detection of 1 ng/mL was achieved, quantitation performance and mass resolution were also characterized. Although a Faraday detector is less sensitive than an electron multiplier, it is stable with fixed gain, and it can also be used in elevated pressures to measure large biomolecules. Therefore, this technology could be useful in the further development of miniature mass spectrometers by increasing background pressures, as well as the development of miniature protein mass spectrometers.