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was reported to be very soft producing very few molecular fragment ions. The system has been used
very successfully in the analysis of triazine herbicides and organo-phosphorus pesticides and excellent
specificity and sensitivity was achieved. A number of different forms of this device were described, but
they are all basically similar to that shown in Figure 9.17. An interesting form of the thermospray
interface has been described by De Wit et al. [14] in 1987, for use with open tubular LC columns.
Blakely and Vestal [15] employed the thermospray system with the quadrupole mass spectrometer, and
demonstrated that it could provide stable vaporization and ionization at flow rates up to 2 ml/min, with
an aqueous mobile phase. If the mobile phase contained a significant amount of ions in solution (ca 10
-4
to 1.0 M), no extra thermal ionization source is required to achieve detection of many non-volatile
solutes at the submicrogram level. They found that with weakly ionized mobile phases, a conventional
electron beam needs to be used to provide gas-phase reagent ions for the chemical ionization of the
solute.
Figure 9.18
The Vestec Model 210 Thermospray Interface
