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number of proteins including bovine albumin. An example of a spectrum they obtained for bovine
albumin is shown in Figure 9.7.

Figure 9.7
The Matrix-UV-Laser Desorption Spectrum of Bovine Albumin
Reprinted with permission from M. Karas and F. Hillenkamp, Anal.
Chem., 60(20)(1988)2299., Copyright 1988 American Chemical Society
The spectrum shows the single, double and triple charged parent ions, the molecular weight of the
parent ion being about 66750 daltons. The standard deviation of the parent ion peak is about 300
daltons. It is seen that the technique can help provide mass spectrum of very large molecules,
apparently with little or no decomposition. This type of system would be ideal to combine with the
liquid chromatograph, but for satisfactory operation it must again evoke the need for a transport
interface.

Field Desorption Ionization

The process of field desorption involves the extraction of ions from a sample (deposited on a specially
prepared surface) by the use of extremely high electrical fields. The preparation of the emitting surface
can be quite involved and appears to be somewhat of an art as well as a science. A diagram of the field
desorption source is shown in Figure 9.8. The emitter