We present and discuss in detail the design and characterization of a new linear quadrupole ion trap with additional ion ejection and acceleration electrodes that is coupled to a time-of-flight mass spectrometer. Mass spectra of Coulomb crystals consisting of Ca + ,CaO + and CaOH + ions were recorded with a post-ejection-acceleration scheme yielding a mass resolution of m / Δ m ≈700. The second order rate constant for the reaction Ca + + N 2 O → CaO + + N 2 was measured to test the usability of this apparatus for ion-molecule reaction studies. The rate constant was found to be 5.49(32)·10 −11 cm 3 s −1 which is compared with previous literature values. Owing to the high mass resolution achieved, the present instrument is an ideal tool for the study of the products of complex chemical reactions involving Coulomb crystals.