Page 323 - Tandem Techniques

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More recently, Turula and Haseth [13] have employed the particle beam atomizing technique, originally
described by Browner et al. [14-16]. This technique was initially employed as a mass spectrometry
interface but has now been adapted for use in LC/FTIR. The system was employed with a standard
liquid chromatograph (the Hewlett-Packard 190L binary gradient instrument) and the spectra were
obtained on a Perkin Elmer 1725X FTIR spectrometer. The particle beam atomizer is shown in Figure
8.13.

Figure 8.13
The Particle Beam Atomizer.

In normal operation the column eluent is pumped through a small capillary and exits as a liquid jet. The
emitted stream is then nebulized with a stream of helium gas. The droplets of liquid, so produced, pass
into a desolvation chamber, where the solvent molecules evaporate and are removed. The size of the
droplets is controlled by the diameter of the capillary (ca 16-25 µm I.D.). The rate of evaporation rises
as the sizes of the drops decrease due to the increase in relative surface area. The solute particles then
pass into a separator chamber which is evacuated, and then strike an infrared transparent substrate. This
substrate is then placed in the FTIR spectrometer and the spectrum obtained by co-adding 1000-2000
single-beam scans. The nebulizer was not used with a transport collector,