876 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS This quantity is then indicative of the amount of spray deposited on the slide and can be used as the "mass of collected material." Since the re- sults are given as cumulative weight per cent, it is not necessary to trans- late this amount into the weight of the entire spray. By multiplying the weight of aerosol sample by the concentration of dye added, one can de- termine amount of dye present in total aerosol sample which is then dis- tributed over the slides in the same ratio as the particle size distribution. Satisfactory results were produced with the suspension-type aerosols. However, since a nonvolatile material was added to the particles as a dispersing agent, a slightly different particle size distribution was ob- tained. Both the Microcrystals and Calcomites of Sulfadiazine produced acceptable results. Studies are currently underway to adapt this method to a variety of other aerosol products. Since the dye used in this study is water insol- uble, its use is limited to those aerosols containing alcohol and other simi- lar solvents. Other dyes are being investigated for use with aerosols con- taining water. SUMMARY AND CONCLUSIONS Fluorometry was evaluated as a tool in determining the particle size distribution of aerosols. Various fluorescent substances were investigated for this purpose. The particle size distributions of two hair sprays having different particle size distribution were evaluated by this method and the results compared with those obtained by a weight by difference method. This method was then used to determine the particle size distribution of aerosols containing insoluble materials of known particle size. Blancophor AW High Concn. was found to be acceptable as a tracer in this study, providing its concentration did not exceed about 0.05% by weight. The comparison of the fluorometric and the weight-by-differ- ence methods to determine the amount of material deposited in each stage of the Cascade Impactor showed that either method could be used how- ever, fluorometric analysis can be considered to be of greater accuracy. (Received June 4, 1971) REFERENCES (1) Dautrebande, L., Importance of Particle Size for Therapeutic Aerosol Efficiency, Micro- aerosols, Academic Press, New York, 1962, pp. 37-57. (2) Dautrebande, L., Lung deposition of fine dust particles, AMA Arch. Ind. Health, 16, 179 (1957).

PARTICLE SIZE DETERMINATION 877 (3) Dautrebande, L., Studies on deposition of submicronized dust particles in the respiratory tract, Ibid., 19, 383 (1959). (4) Brown, J. H., Influence of particle size upon the retention of particulate matter in the human lung, Amer. J. Pub. Health, 40, 450 (1950). (5) Sciarra, J. J., McGinley, P., and Izzo, L., Determination of particle size distribution of selected aerosol cosmetics. I. Hair sprays, J. Soc. Cosmet. Chem., 20, 385 (1969). (6) De Silva, J., and D'Arconti, L., The use of spectrofiuorometry in the analysis of drugs in biological materials, J. Forensic Sci., 2, 184 (1969).