In the EU, there is an increasing need for regulatory agencies to establish health-based threshold limits for airborne particles. A necessary prerequisite for such projects is the validation and comparison of existing and newly developed particle analyzers. Corresponding proficiency tests have often been carried out with the help of inter-laboratory tests using test aerosols. Such test aerosols were produced with different generator systems at the technical center of the Institute for the Research on Hazardous Substances (IGF) in Dortmund. The generated particles covered the micro and the nanoscale range, but a long term stable and reproducible formation of low particle number concentration of nano-sized particle atmosphere was not achieved yet. Inspired by a method of monodisperse droplet generation, we have coupled a flame generator with a droplet generator, and examined concentration and diameter of particles formed as a consequence of different precursor concentrations and applied droplet frequency. In addition, the reproducibility of the method was tested daily, and the nanoparticles were collected and characterized microscopically. Finally, the measurements of particle size distribution were mathematically examined. The resulting fits allow for the prediction of the median particle diameter as a function of the precursor concentrations used and the frequency of the droplet generator. Overall, the performed experiments confirm that this system meets all requirements with regard to low number concentrations, long-term stability and reproducibility, and should therefore be suitable for further inter-laboratory round robin tests.