DIMETHICONE QUANTITATION USING FTIR 281 Figure 9. Blank-subtracted dimethicone-spiked blank formulation spectrum, 1.00% w/w spiked level. storage and recall would be the most advantageous from an analysis time consideration therefore, a thorough study of the precision and accuracy of dimethicone quantitation using blank-subtraction is ongoing. REFERENCES (1) Federal Regulatory Agency, 21 CFR Part 347--Skin protectant drug products for over-the-counter human use, Federal RegistersProposed Rules, 48 (32), 6832 (1983). (2) T. Rihs, Identification and determination of dimethylpolysiloxanes in pharmaceutical preparations, Pharm. Acta Hdv., 49 (9), 550-557 (1971). (3) United States Pharmacopeial Convention, USPXX/NFXV, Twentieth Revision, (United States Phar- macopeial Convention, Inc., Rockville, MD, 1979), p 724. (4) United States Pharmacopeial Convention, USPXX/NFXV, Supplement 3, (United States Pharmacopeial Convention, Inc., Rockville, MD, 1982), p 246. (5) United States Pharmacopeial Convention, USPXX/NFXV, Addendum a to Supplement 3, (United States Pharmacopeial Convention, Inc., Rockville, MD, 1982), p 593. (6) F. Burton, Westwood Pharmaceuticals, Inc., Private communication, 1983.