j. Soc. Cosmet. Chem., 37, 267-277 (July/August 1986) Nitromusks: False positives in the analysis for nitrosamines MARK R. SINE, The Procter & Gamble Company, Fabric, Hardsurface, and Beauty Care Technology Division, Miami Valley Laboratories, Box 39175, Cincinnati, Ohio 45247. Received March 24, 1986. Synopsis Nitrosamine analyses using a gas chromatograph (GC) interfaced to a thermal energy analyzer (TEA) showed "nitrosamine-like" signals for extracts of shampoo, conditioner, and antiperspirant/deodorant products. In several instances these "nitrosamine-like" responses could not be distinguished from the re- tention time of N-nitroso-N-methyl dodecylamine (NMDDA) however, the levels appeared unrealistically high (ppm instead of ppb) and the reproducibility was poor. Re-examination of these samples by gas chromatography/mass spectrometry (GC/MS) disproved the presence of NMDDA and identified the com- pound producing the GC/TEA signal (i.e., the false positive) as a nitromusk compound, musk xylol, present in the product fragrances. Other "nitrosamine-like" GC/TEA signals have also been linked to other nitromusk perfume raw materials (PRM) including moskene and musk ketone. Nitromusks are perfume components in numerous cosmetic products and can interfere with the GC/TEA analysis of nitrosamines. Confirmatory experiments such as GC/MS, wet chemical procedures, or UV-photolysis should be run in conjunction with any GC/TEA determination of nitrosamines. An example of a false positive in a shampoo extract is presented. INTRODUCTION N-nitrosamines have received widespread publicity as a group of potentially carcino- genic compounds. Their presence has been reported in a wide range of materials in- cluding cosmetics (1) and shampoos (1) and can be linked to the presence of potential nitrosamine precursors including amines (particularly secondary amines (2,3)), amine oxides (2), and quaternary ammonium salts (2,3) often used in cosmetic products. Since minimization of nitrosamine levels is of high interest to the cosmetic industry, a reliable and sensitive analytical technique is necessary to monitor their presence. One particular technique which has been widely used in the industry for measuring volatile nitrosamines is the GC/TEA system. In the GC/TEA system, compounds which elute from the GC column are passed into the TEA where they are thermally degraded. N-nitrosamines, which have the general structure RtR2N-N = O, decompose, releasing the nitrosyl radical ('NO) and various organic materials (4). The degraded materials are carried by an oxygen-free carrier gas (helium) through a cryogenic trap and/or filter which traps the organics but allows the ß NO to pass into an ozone reaction chamber. Ozone combines with 'NO to form electri- 267