Page 312 - Tandem Techniques
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dispersion that might cause loss of chromatographic resolution. The minimum mass required to provide
a satisfactory spectrum will depend on the characteristic absorbance of the substances being monitored.
Nevertheless, the results indicated that between 50 and 100 ng of sample would provide a recognizable
spectrum.
Subsequently, Gagel and Bieman [9] modified the design of their nebulizer to improve the deposition
procedure, and to make it more suitable for spraying aqueous solvents. The intent was to reduce the
spreading of the eluent during deposition and to concentrate the material in a smaller area to improve
the sensitivity. The modified jet design involved the use of two nitrogen streams in the nebulizer head
very similar to one of the types examined by Lange and Griffiths [10] and a diagram depicting their
alternative jet design is shown in Figure 8.4.
Figure 8.4
The Modified Nebulizer of Gagel and Bieman.
The column eluent was mixed with nitrogen under pressure in a high pressure mixing T. The nitrogen-
eluent mixture was directed to the deposition surface through a syringe needle, fitted to the other port of
the high-pressure T. The syringe needle itself was situated inside another
