| Abstract: | Optimization of the operating conditions for desorption chemical ionization (D/CI) mass spectrometry has been evaluated on the production of molecular ion species as well as structurally informative fragment ion species with sucrose as a main model compound. Among various parameters examined, it was found that configuration and heating rate of the emitter wire were significantly concerned with the desorption efficiency, while chamber temperature played an important role on the control of the fragmentation process rather than the desorption process. Therefore, the conditions for optimal molecular ion species are quite opposed to those for optimal fragment ion species. The former can be achieved by the use of the highest heating rate combined with the lowest chamber temperature. Under the optimal operating conditions, a 20 ng sample of sucrose is adequate for recording a clear mass spectrum with good reproducibility, where [M·NH4]+ (m/z 360) is the base peak and the glycosyl ion [S·NH3]+ (m/z 180) also has moderate abundance (rel. int., 40%). |
