ANALYSIS OF HIGH-MASS BIOMOLECULES USING ELECTROSTATIC FIELDS AND MATRIX-ASSISTED LASER DESORPTION IONIZATION IN A FOURIER-TRANSFORM MASS-SPECTROMETER/

A new decelerating technique that places de potentials on the orthogon al excitation and receiver plates as well as the rear trapping plate ( conductance limit) of the source cell of a dual cubic cell has been ap plied to the standard matrix-assisted laser desorption/ionization Four ier transform mass spectrometry technique, When this five-plate trappi ng method is applied, high-mass ions with large translational kinetic energies can be trapped efficiently and detected, Using this approach, low-resolution spectra of carbonic anhydrase (MW = 29 000), egg album in (MW = 45 000), and bovine albumin (MW = 66 000) have been obtained, Because the new decelerating method requires no modification to the e xisting cell, it is also possible to obtain high-resolution spectra fo r compounds with masses of ca. 14 000 Da and lower. Utilizing the five -plate trapping method, a bovine insulin spectrum with a resolving pow er of 20 000 was obtained, It is not yet possible to obtain higher res olution for the higher mass proteins, The reasons for this difficulty are currently being investigated.