18 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS comparable value of 2.8 in the case where the human subjects' skin was heated to 33øC prior to the exposure by solar simulator (7). The result demonstrates that environmental factors such as skin temperature, in addition to the spectrum and the intensity of UV irradiation, may affect the SPF value of the sunscreen preparation tested. When these factors are considered, it is readily seen why wide variations in the SPF value have been reported by different investigators using the same sunscreens. Therefore, when considering the actual conditions in which sunscreen preparations are applied under natural sunlight, attention should be paid to the spectral output, the UV intensity, and many environmental factors. Such factors must also be considered when using artificial sunlight including solar simulator for determining the SPF value otherwise, the SPF value determined may differ from the value in actual usage condition. We would recommend that the proposed FDA regulations regarding solar simulators specify more narrowly the energy emissions in the UV and IR ranges which approximate more closely natural sunlight conditions. Furthermore, the room temper- ature and relative humidity in case of solar simulator exposure should be determined an d recorded. REFERENCES (1) Sunscreen drug products for over-the-counter human use, Federal Register, 43, 38206-38269 (1978). (2) M. Fukuda, M. Nagashima, A. Munakata, K. Nakajima and S. Ohta, Effects of biological and physical factors on ultraviolet erythemal and pigmentary response: Skin complexions and environmental ultraviolet radiation,J. Soc. Cosmet. Chem. Japan., 13, 20-28 (1979). (3) D. S. Berger, The sunburning ultraviolet meter: Design and performance, Photo?hem. Photobiol., 24, 587-593 (1976). (4) Y. Nakayama, F. Morikawa, M. Fukuda, M. Hamano, K. Toda and M. A. Pathak, Monochromatic radiation and its application: Laboratory studies on the mechanism of erythema and pigmentation induced by psoralen, in Sunlight and Man, T. B. Fitzpatrick, Editor, (University of Tokyo Press, Tokyo, 1974)pp. 591-611. (5) K. H. Kaidbey and A.M. Kligman, Laboratory methods for appraising the efficacy of sunscreens, J. Soc. Cosmet. Chem., 29, 525-536 (1978). (6) G.J. LeVee, R. M. Sayre and E. Marlowe, Sunscreen product effectiveness can vary with different simulated solar ultraviolet spectra,J. Soc. Cosmet. Chem., 31,173-177 (1980). (7) R. M. Sayre, D. L. Desrochers, E. Marlowe and F. Urbach, The correlation of indoor solar simulator and natural sunlight testing of sunscreen products, Arch. Dermatol., 114, 1649-1651 (1978).

J. Soc. Cosmet. Chem., 33, 19-25 (January/February 1982) Analysis of 1,4-dioxane in ethoxylated compounds by gas chromatography/mass spectrometry using selected ion monitoring BRUCE A. WALDMAN, Union Carbide Corporation, Tarrytown Technical Center, Tarrytown, NY 10591. Received August 31, 1981. Synopsis A combined GAS CHROMATOGRAPHIC/MASS SPECTROMETRIC method for the analysis of 1,4-dioxane has been developed using SELECTED ION MONITORING of its molecular ion. The specificity obtained eliminates the need for extensive sample pre-treatments. Samples are diluted with an aqueous or methanolic solution of perdeuterotoluene (internal standard). Separation is accomplished by direct injection onto a Chromosorb 103 column. The peak area of 1,4-dioxane is ratioed to that of perdeuterotoluene and compared to a standard mixture. A detection limit comparable to the Birkel method of 0.5 mg/kg is readily obtained. Comparisons with data obtained from the Cosmetic Toiletry and Fragrance Association round robin study of 1,4-dioxane analysis, show good agreement between this method and the standard Birkel procedure for samples of Sodium Laureth Sulfate, Polysorbate 60, and PEG-8. Up to 15 determinations can be made in an eight-hour day (13 samples, 2 standards) with a relative precision of + 10% at a 1.0 mg/kg concentration. INTRODUCTION The Cosmetic Toiletry and Fragrance Association (CTFA) sponsored a round robin study to compare methods for the analysis of 1,4-dioxane in ethoxylated matrices (1). This study served to obtain an interlaboratory correlation of the accepted Birkel procedure (2) and to investigate new methodology. The types of ethoxylated compounds studied were Sodium Laureth Sulfate, Polysorbate 60 and PEG-8. The method described here was used in the study under the code-laboratory 18. The development of a combined Gas Chromatographic/Mass Spectrometric (GC/MS) method for 1,4-dioxane was begun to fulfill the need for a rapid, selective 1,4-dioxane analysis for both volatile and non-volatile samples. The Birkel method is labor intensive, restricted to non-volatile samples and capable of running only two or three samples per day. Direct injection methods are faster but generally require a specialized and dedicated GC system (3). Methods such as purge/trap GC and headspace GC have suffered from poor sensitivity and precision and show best utility on non-volatile samples. 19