At the last ANZSMS conference we reported the construction of a computerised control system for a pentaquadrupole mass spectrometer, capable of performing MS/MS/MS experiments. This presentation describes the next phase in our work.

Here we report the results of preliminary experiments in commissioning the spectrometer. The transmission efficiency of the entire instrument for the total ion beam was found to be about 5 - 10% (or approximately 50% per stage). Mass spectra of benzyl chloride and m-xylene acquired with the first, third and fifth quadrupoles show that a resolution of at least 100 is obtainable, which is expected to be adequate for experiments planned in the next 6 to 12 months. The metastable decompositions of the molecular ion of m-xylene (m/z 106) and [M-l] (m/z 105) have been observed in a preliminary test of the MS/MS capabilities of the instrument. By enclosing the second and fourth quadrupoles we have also been able to perform CAD/CID experiments on m-xylene.

The goal of these experiments is to prepare the ground for work examining chiral effects in the ion-molecule reactions of 2-butanol and 2-butylamine. The experiments are envisioned as follows:

Figure 1. Ion-molecule experiment involving optical isomers

We intend to examine all the available combinations of (R)-2-butanol, (S)-2-butanol, (R)-2-butylamine and (S)-2-butylamine. Interactions between the optical isomers are expected to produce different fragmentation spectra of the proton-bound dimer.