384 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS REFERENCES (1) Fisher, R. A., The Design of Experiments, Oliver and Boyd, Edinburgh and London, 1951. (2) Service Manual, The Kartridg Pak Co., 807 W. Kimberly Rd., Davenport, Iowa, Copy- right, 1966. (3) Dixon, W. J., and Massey, F. J., Jr., Introduction to Statistical Analysis, 2nd Edition, McGraw-Hill, New York, 1957, p. 436. (4) Genetron© Propellants and Aerosol Formulations, Allied Chemical Industrial Chemicals Division, Morristown, N.J. (5) Dorr, R. O., Kartridg Pak Co., personal communication, May 17, 1968.

J. Soc. Cosmetic Chemists, 20, 385-394 (May 27, 1969) Determination of Particle Size Distribution of Selected Aerosol Cosmetics. I. Hair Sprays JOHN J. SCIARRA, Ph.D., PATRICIA McGINLEY, B.S., and LOUIS IZZO, B.S.* Presented September 12, 1068, Seminar, Boston, Mass. Synopsis Several methods for the determination of particle size distribution of aerosols have been reviewed. The Cascade Impactor was investigated and found suitable for classi- fying the particle size distribution of aerosols between 0.5 and 32.0 u. Various sampling chambers were evaluated and the design of the chamber was found to be an ixnportant factor for particle size distribution. A modified distilling flask proved to be most suitable for this purpose. The particle size distribution of two aerosol hair spray formulations was deter- nilned using this technique. Particles between 0.5 and 32 u were classified with special attention given to those particles below 10 u in diameter. Several valve combinations were studied and evaluated on the basis of the proportion of particles below 10 u. The Cascade Impactor has been shown to be satisfactory for evaluating the toxicological potential of these aerosols based upon particle size distribution and upon other considerations. INTRODUCTION Since the first aerosol insecticide was introduced during the late 1940's a great deal of attention has been devoted to the subject of particle size analysis. The particle size of an aerosol spray is important, both from efficacy and toxicity considerations. In addition to particle size, one must also take into account particle size distribution. Whereas, in many cases, it may be desirable to have a spray of uniform particle size, * St. John's University, College of Pharmacy, Jamaica, N. ¾. 11432. 385