382 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 5 I I , 50 20 MINUTES 2 Figure 2. Separation of parabens on 30-cm Vydac reversed phase-chromatographic column. Eluent equals 20:80 methanoh H•O: flow rate equals 0.33 ml/min: attenuation equals 0.64 absorbance units full scale: (1) solvent front (2) methylparaben (3 t•g) (3) ethylparaben (3 t•g) (4) propylparaben (4 t•g) (5) butylparaben (6 t•g)

ANALYSIS OF PARABENS BY LIQUID CHROMATOGRAPHY 383 i I I I 1 2 3 4 I i CARBO-N NUMBER Figure 3. Graph of logarithm of corrected retention vo]u•ne rs. carbon number of ester (retention volume of compound minus retention volume of solvent front, i.e., Vr - Vo)

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