ANALYSIS OF PAINT-ON ARTIFICIAL NAILS 63 2.5 100 80 •: 40 20 0 4000 MICROMETERS 6.0 8.0 3.0 4.0 5.0 10 16 20 25 50 400 200 3500 3000 2500 2000 1800 1600 1400 WAVENUMBER 800 600 (CM •) Figure lb. IR Spectrum of Pure Poly(methyl methacrylate). and supports the inference that diethyl phthalate is present in the sample. Use of the Perkin-Elmer data station to take the difference between the two infra-red spectra results, after smoothing and expansion, in the spectrum of Figure 3. This spectrum is somewhat cluttered, but compares favorably with that of pure diethyl phthalate. In most cases, no further identification would be required. In this case, extraction of the polymer powder with methanol and subsequent evaporation of the methanol left a liquid whose NMR and IR spectra were indistinguishable from those of diethyl phthalate. I , I , I , I , I 8 7 6 5 4 3 2 1 p.p.m. 0 Figure 2a. NMR Spectrum of Plasticized Poly(methyl methacrylate).

64 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 2.5 100 • 60 • 40 i- 20 MICROMETERS 3.0 4.0 5.0 6.0 6.0 10 16 20 25 50 0 I I I 4000 3500 3000 400 200 2500 2000 1800 1600 1400 WAVENUMBER 600 600 (CM -• ) Figure 2b. IR Spectrum of Plasticized Poly(methyl methacrylate). Homopolymers of the various methacrylate esters are easily distinguished from one another by either NMR or infra-red spectra. NMR and IR spectra of themselves, however, do not in general permit a distinction to be made between a copolymer and a polymer blend. For example, Figure 4a is the NMR, and 4b the IR, spectrum of a copolymer containing about 70 wt-% ethyl and 30 wt-% methyl methacrylate groups, with about 2.6% added benzoyl peroxide. Except for possible variations due to varying MICROMETERS 4.0 5.0 6.0 7.0 6.0 9.0 10 12 14 16 3000 2500 2000 1800 1600 1400 WAVENUMBER 1000 800 600 (CM ') Figure 3. Spectrum Recovered from Spectra lb and 2b by Difference. Compare Diethyl Phthalate.