High-resolution time-of-flight spectra obtained using the MULTUM II multi-turn type time-of-flight mass spectrometer...

This paper describes experiments demonstrating the high mass-resolving power of the MULTUM II multi-turn type time-of-flight (ToF) mass spectrometer with a 1.308-meter circuit controlled by four toroidal electric sector fields(1) and an electron ionization (EI) ion source. A mass resolution of 250,000 [full-width at half maximum: (FWHM)] was obtained for N(2)(+) after a flight time of 9.0 ms (flight cycles: 1,200, flight length: 1,500 M). A doublet of (12)C(5)H(5)(14)N and (13)C(12)C(5)H(6) (m/Deltam = 9,746; Deltam: mass difference of doublet, m: mass of lighter ion of doublet) was separated and a mass resolution of 91,000 (FWHM) was obtained. A doublet of CDCl(2) and CH(2)Cl(2) (m/Deltam = 54,162) was also separated. A mass resolution of 115,000 (FWHM) was then achieved. When one peak of these doublets was used as a calibrant, the mass of the other peak was determined within a few ppm by mass difference. The ToF depending on the square of m/z was significantly larger than the systematic errors in the ToF, so that good mass accuracy was obtained by one-point mass determination.