is developing an instrument for online, real-time measurement of size and chemical composition of individual aerosol particles. Particles are sampled from an aerosol by using aerosol beam techniques. Experimental results and a theoretical model for particle beams have been used to design an improved beam generator. The apparatus comprises an exchangeable capillary nozzle and three vacuum chambers in series. Collimated by the beam system the particles enter the ionization chamber of a time-of-flight mass spectrometer, where they can be vaporized and ionized by the pulse from a Q-switched YAG laser. Analysis of the generated ions with the mass spectrometer provides information on the chemical composition of the particles. This paper reports the first results obtained with a new experimental setup, based on earlier work. Mass spectra were observed for a static target and particles of sodium chloride. The results were compared with spectra obtained with a LAMMA-500.