Page 492 - Tandem Techniques

Page 477

of the spectrum obtained for 100 ng of Tyr-bradykinin extracted from a thin layer plate is shown in
Figure 12.14.

Figure 12.14
Mass Spectrum for 100 ng of Tyr-bradykinin
Extracted from a Thin Layer Plate
Reprinted with permission from A. I. Gusev, A. Proctor, Y. I.
Rabinovich and D. M. Hervcules, Anal. Chem., 67(11)(1995)1805,
Copyright 1995 American Chemical Society.

It is seen from the insert that the signal to noise ratio is about 300 to one and thus, assuming a signal to
noise of 3 is necessary to unambiguously identify the presence of a mass peak, then the minimum
detectable mass is about 1 ng.

A further extension of the technique by Gusev et al. [10] involved the development of the TLC plate
followed by mobile phase removal by drying in an appropriate manner. Second, the matrix ionization
aid is formed separately as a thin film on a stainless steel plate. The reagents, dissolved in an
appropriate solvent, are sprayed onto the steel plate and dried. The thin layer plate is then sprayed with
an appropriate solvent and while wet, the stainless steel plate is pressed onto the thin layer plate (the
coating being in contact with the thin layer plate).