COAXIAL CONTINUOUS-FLOW FAST-ATOM-BOMBARDMENT VS ELECTROSPRAY-IONIZATION - A SENSITIVITY COMPARISON ON A MAGNETIC-SECTOR INSTRUMENT

The performance of an electrospray (ESI) source was evaluated and comp ared to that of a coaxial continuous-flow fast-atom bombardment source on a magnetic mass spectrometer using ten different peptides over the mass range of 400 to 3500 Da and using a variety of scanning modes. R esults show that sensitivities using the two ionization techniques are similar, with limits-of-detection in the attomole to low femtomole ra nge. In addition, proteins fan be routinely detected using ESI at femt omole levels. The observance of the noncovalent complex of RNase A and cytidine 2'-monophosphate yields evidence that these complexes can be studied using instruments that operate at high accelerating voltages.