j. Soc. Cosmet. Chem., 36, 101-104 (January/February 1985) Abstracts The Annual Scientific Meetings and Seminars of the Society of Cosmetic Chemists are important venues for informing the participants about the state of the art and recent technical advances in the field of Cosmetic Science. To provide broader dissemination of that information, the Publication Committee has decided to publish abstracts of the technical presentations made at these Meetings and Seminars in the Journal.--The Editor. Society of Cosmetic Chemists ANNUAL SEMINAR May 9-10, 1985 St. Louis, Missouri Program arranged by the Society's Committee on Scientific Affairs Jan Curry, Chairman, 1985 Stephen M. Greenberg, Ph.D., Chairman, 1984 SCIENTIFIC SESSION I SUSPENSION TECHNOLOGY Effect of particle interactions on the physical properties of suspensions Stanley L. Hem, Ph.D., and Joe L. White, Ph.D., Purdue University, School of Pharmacy and Agronomy, W. Lafayette, IN 47907 Physical properties of suspensions such as viscosity, settling, sedimentation, and water-retaining prop- erties are largely controlled by particle interactions. The use of fiber optic Doppler anemometry for the direct measurement of particle interactions is dem- onstrated by studying the effect of ionic strength and valence of the counter-ion on the floccutation of monodisperse latex suspensions having a fixed negative surface charge. The area under the curve of the modified Lorentzian power spectrum obtained by fiber optic Doppler anemometry is shown to be directly related to the colloidal fraction of particles that exhibit Brownian motion. The effects of par- ticle size, volume fraction, surface charge, and shear on particle interactions in suspensions as determined by fiber optic Doppler anemometry are correlated with physical test results. Physical stability of suspensions Joel L. Zatz, Ph.D., Rutgers College of Pharmacy, P.O. Box 789, Piscataway, NJ 08854 Thorough wetting and particle dispersion are im- portant first steps in the formation of uniform sus- pension systems. The critical surface tension of the solid provides guidance in the selection of surfac- rants used to promote wetting. Wetting character- istics are related to deposition of particles onto the container walls during storage. Size and density of particles and rheology of the medium play impor- tant roles in determining sedimentation rate. Vis- cosity can be adjusted within wide limits so as to modify the settling rate. However, the type of flow behavior is of utmost importance. Materials chosen as suspending agents must provide resistance to sed- imentation, while still permitting high shear op- erations such as shaking and pouring. Particle floc- culation affects sedimentation rate as well as the degree of compaction that takes place within the sediment. In general, coarse deflocculated systems settle as individual particles to form a "caked" sed- iment, one which is extremely difficult or impos- sible to resuspend. Flocculation can be induced by several mechanisms. Compounds that can function as flocculants include electrolytes, polyols, surfac- tants, and polymers. A practical approach in formulating suspension antiperspirants Jitendra Patel, Ph.D., Walter V. Fackler, Ph.D., and John R. Roheim, Ph.D., Armour-Dial, Inc., 15101 N. Scottsdale Road, Scottsdale, AZ 85260 In the past, antiperspirant products' successes were 101

i02 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS rewarded by consumer acceptance and brand loy- alty. However, changing consumer preferences, heavy advertising campaigns, and government reg- ulations have changed the traditional market ori- entation and have resulted in a greater emphasis on the proper selection of formulation additives by the cosmetic chemist. The discussion will provide a practical approach in formulating successful anti- perspirant delivery characteristics. The cosmetic chemist is challenged with new rheological deci- sions in formulating antiperspiran, t products. This paper discusses the role of suspending agents and various delivery systems employed in antiperspirant technology, with emphasis on the practical use of various formulation additives. The technology and effectiveness of suspending agents will be discussed and data and formulations with these additives will be presented. Bentonites in cosmetics Joseph T. Suchan, B. S., Whittaker, Clark & Dan- iels, Inc., 1000 Coolidge St., South Plainfield, NJ 07080 Bentonite is a very unique clay that has swelling properties that are particularly attractive to the cos- metic industry. In addition to its swelling proper- ties, bentonites are used in many industries for var- ious applications. It is used in the production of wine and fruit juices for clarification. It has been used in the detergent industry to hold grease and dirt. The physical and chemical properties of ben- tonite will be discussed. Various bentonites are compared and recommended uses will be suggested. Since bentonite can be difficult to wet and disperse, proper methods will be mentioned. The proper use in cosmetic formulas will be discussed. SCIENTIFIC SESSION II PRESERVATION Resistance of Pseudomonas species to preser- vatives in cosmetic formulations Susan M. Lindstrom, M.S., and Patricia Imig Bowman, Ph.D., Avon Products, Inc., Division Street, Suffbrn, NY 10901 An organism presumptively identified as Pseudo- monas cepacia, isolated from an oil-in-water emul- sion containing methyl paraben and imidazolidinyl urea (IDZU), demonstrated resistance to IDZU at concentrations greater than 0.5 %. This led to iden- tification $f other IDZU-resistant Pseudomonas species from cosmetic products. Studies were con- ducted to determine if the organisms maintained IDZU resistance after repeated transfers on labora- tory medium and if resistance to alternate preser- vatives was present. The susceptibility of the or- ganisms to various concentrations of IDZU was tested by dissolving the compound in 0.1% nu- trient broth. This solution was inoculated and sam- pled intermittently. The organisms survived in a solution of IDZU at 2.0%. Growth was measured only after prolonged incubation (72 hours). Isolates transferred directly from products and isolates pre- pared after several transfers on laboratory medium exhibited similar resistance patterns. Minimal in- hibitory concentrations and kill rate studies were conducted in nutrient broth containing IDZU. An MIC of greater than 4.0% IDZU was demonstrated. During the kill rate study, a 106 org./ml inoculum was reduced by at least 99.9% within 24 hours and the surviving cells increased to 108 org./ml after 7 days. The inhibitory activity of other preservatives was examined. An MIC of less than 0.25% was demonstrated with diazolidinyl urea. Evaluating the antimicrobial efficacy of preser- vative systems: Considerations for determining stability with regard to regulatory standards Ronald L. Schlitzer, Ph.D., and Ruth Ann Rosen- thal, M.S., Alcon Laboratories, Inc., 6201 S. Freeway, P.O. Box 1959, Fort Worth, TX 76101 A method is described for evaluating the eft&five- ness of preservative systems based on regulatory guidelines. Formulations containing antimicrobial agents were challenged separately with bacteria, yeast, and molds. The number of survivors was de- termined by aerobic culture. Kinetic values defining the preservation efficacy were calculated for different exposure periods. A numerical ranking profile was developed to compare preservative systems in dif- ferent formulations. This method provides a rapid and quantitative means for evaluating preservative systems early in their development and monitoring them and predicting their stability and compliance with compendial and regulatory guidelines. Synergistic inhibition of fungi by selected in- hibitors C. S. Llabres, M.S., and D. G. Ahearn, Ph.D., Georgia State University An N-chloramine (0.1%) and diazolidinyl urea (0.3%) were evaluated separately and in various combinations for their anti-microbial activities. The N-chloramine gave D-values (26øC) of less than one rain for Staphylococcus aureus and Pseudomonas aeru- ginosa, 5 min for Candida Lipolytica, 11 min for Serratia marcescens and 2 h for Alperigillusfumigatus. The diazolidinyl urea had D-values between 42 rain