Fourier transform quadrupole linear ion trap mass spectrometer

DESCRIPTION (provided by applicant): This Phase I SBIR project will develop a commercially viable Fourier Transform quadrupole Linear Ion Trap MS (FT-LIT MS). This instrument would provide mass resolution better than 100,000, with low ppm mass accuracy. Si nce this device does not require a large magnet or complicated ion injection optics (i.e. C-trap in an Orbitrap), the cost will considerably less than a conventional FT-ICR MS or an Orbitrap MS. Many experiments (MS/MS, IRMPD, ETD/ECD, ion-ion, ion-molecul e interactions, etc.) which are very difficult to do in an Orbitrap MS could be done in this FT-LIT MS instrument. Since this device uses a quadrupole to confine ions, it offers more versatility and greater capable than an Orbitrap MS. Although many resear chers have investigated FT mass analysis in quadrupole linear ion traps and 3D Paul ion traps in the past. a variety of common problems were encountered including RF interference in signal detection, space charge effects, and stability of the electronics. In this study, we will address these issues with a unique design of the quadrupole device, a new ion excitation method and a new design of state of the art electronics. A new linear trap will be constructed during Phase I. The quadrupole trapping field ins ide this device will be effected by using a unipolar RF voltage to drive one pair of electrodes, with the other pair of rods maintained at a virtual ground potential for signal detection. An additional pair of RF electrodes are located external to the virt ual ground electrode pair. These additional electrodes are applied an RF voltage equal and opposite to the trapping RF voltage, to cancel out the effects of the RF voltage induced on the signal detection electrode pair by the trapping electrodes. A pre-qua d with bipolar/unipolar switchable RF electronics will be developed for interfacing bipolar multipole ion guide to the unipolar detection quad. Finally, a broadband circular excitation method will be employed to minimize space charge effects. During Phase I development, the ion trap will be operated under high vacuum (10-6 mbar range), and medium resolution (about 10,000) should be achieved. Once the FT-LIT MS concept has been validated, Phase II funding will be used to develop detection electronics that co mbine analog and digital technology for feedback mixing and RF filtering. This should further reduce RF interference of the detection signal and help achieve high detection sensitivity. During Phase II, a temperature regulated highly stable (sub ppm in bot h frequency and amplitude) RF generator will also be designed and built. The linear ion trap will be operated under ultra high vacuum (10-9 ~ 10 -10 mbar) for long transient time high resolution detection. This FT-LIT MS can be configured as a compact low cost, high resolution mass spectrometer and/or used as a high resolution mass analyzer for hybrid MS instrumentation.