Selective Extraction of a Monoisotopic Ion While Keeping the Other Ions in Flight on a Multi-Turn Time-of-Flight Mass Spectrometer.

Using a multi-turn time-of-flight (TOF) mass spectrometer, we have extracted a single xenon isotope ion, 129Xe+, from its orbit at given a lap number without disturbing the rest of isotopes. After detecting the 129Xe+ at 20 laps, the rest of the xenon isotope spectrum was obtained at 30 laps, which generated a TOF spectrum where the TOF difference between 129Xe+ and 130Xe+ was 87.4 μs while 130Xe+ and 131Xe+ were 1.03 μs. The time distance between 129Xe+ and other isotopes can be set by any lap difference that is a factor of 8.7 μs, which depends on the acceleration voltage and the mass of the ion. Method accuracy was verified by comparing the isotopic abundance ratio of the xenon sample after withdrawing one of the ions from the isotope cluster to the abundance ratio obtained from the conventional method. The TOF stability was also evaluated at various lap numbers between 10 to 230.