SOCIETY OF COSMETIC CHEMISTS OF GREAT BRITAIN 61 PAI•ER II (Wednesday, 19th June 1968) Candidates should ansxver FIVE questions from not less than FOUR sections. SECTIO• A 1. Review the use of surface active agents in hair preparations. Particular attention should be paid to showing how the specific properties and structures of different types of surfactant makes them particularly suitable for different product types. 2. Describe the maximum bubble pressure method for measuring surface tension. Discuss the effect of (a) detergent concentration, (b) tem- perature on the surface tension of a detergent solution. The equation log cmc:A - BNc (where A and B are constants and Nc is the number of carbon atoms) has been postulated for calculating the cmc of a homologous series of compounds. For the potassium soaps. log cmc is •.60 - octanoate •.02 - decanoate •.52 - laurate •.86 - myristate •.28- palmitate Using the graph paper provided, calculate A and B. SECTION B 3. A sample of an oily material, claimed to be a non-drying vegetable oil, is offered for sale. What analytical tests xvou]d you apply to it in order to (a) verify its claimed nature, (b) assess its probable suitability for use in cosmetic preparations. Justify your choice of tests. 4. Give an account of the chemistry of oxidative rancidification. What structural features are likely to make a mineral or vegetable oil suscept- ible to the development of rancidity? Briefly describe the practical measures that you would take in order to prevent, minimise or delay the development of rancidity in stored cosmetic raw materials or products.

62 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 5. Define the terms: SECTION C (a) Optical density (or absorbance). (b) Extinction (or absorption) coefficient. A solution containing 3.7 mg of a pure substance in 100 ml of solvent is placed in a 5 mm thick cell, and is found to absorb 24ø//0 of incident light of a certain wavelength. Calculate the concentration of a solution of the same substance, which, after it has been diluted 100-fold, absorbs 43ø//0 of incident light when placed in a 1 mm thick cell, all other experimental condi- tions being identical (log tables are provided). 6. Explain briefly the mechanism of chromatographic separation and discuss the advantage and limitations of the paper, thin-layer, column and gas-liquid techniques for qualitative and quantitative analysis, with special reference to the problems of the cosmetics industry. SECTION D 7. Write brief notes on THREE of the following:- (a) The value of a perfume to a product (b) Citrus oils (c) Acyclic monoterpenes {d) Beta pinene process for the synthesis of perfumery chemicals. 8. What do you understand by the term "perfume"? Give a simple formula for a j asmin or a lilac perfume. Discuss the perfumery problems associated with the following pro- ducts:- (a) Aerosol hair spray (b) Handkerchief perfume (non-aerosol) (c) White toilet soap. SECTION E 9. Give an account of the various ways in which a surface active agent may stabilise on emulsion. What are the factors that control the viscosity of an emulsion? 10. Give an account of the various methods used to determine the viscosity of cosmetic emulsions. In what way do deviations from Newtonian flow properties influence the measurement of viscosity.