We designed a new method-intermittent electrospray for mass spectrometry. In this paper, the primary principle for intermittent electrospray, the high sensitivity property of intermittent electrospray and advantages for protein analysis is described. Because of its high-sensitivity, this method may find extensive applications in analysis of proteins. The instrumental parameters can be controlled during intermittent electrospray if thesoftware of the instrument is reprogrammed. The parameters can be optimized to give better data. The parameters that can be controlled include tip potential, nozzle potential, flow rate, nebulizer gas flow, curtain gas flow and so on. The instrumental parameters can be changed during different electrospray process in this program. Each process has its own parameters. Then this program runs in cycle to electrospray intermittently. Intermittent electrospray has many advantages for mass spectrometry, which continuous electrospray doesn't have. For example, biological samples are always so little in quantity and the concentration of these samples is so low that many problems are encountered in the determination. But now this kind of samples can be analyzed by intermittent electrospray. Sample solutions are condensed at tip during nonionization time when the solvent is evaporated. After that the condensed sample solution is sprayed in a short time. Because the concentration of the solution is increased, the sensitivity is also improved. So satisfied results from the biological sample can be obtained. Some factors (such as tip potential, sample solution flow) that may influence sensitivity were studied.

Key words: IONISE (=IONIZE), SENSITIVITY, PROTEIN, MASS SPECTRA