A new method has been developed and validated for determining the organic impurities in D&C Violet No. 2 (1-hydroxy-4-[(4-methylphenyl)amino]-9,10-anthracenedione). The color additive is listed under 21 CFR 74.1602 and 74.2602 for use in externally applied drugs and cosmetics and is required to be batch certified by the U.S. Food and Drug Administration. Four impurities are determined: three intermediates (<i>p</i>-toluidine, PT; 1-hydroxyanthraquinone, MHAQ; and 1,4-dihydroxyanthraquinone, DHAQ) and one subsidiary color (1,4-bis[(4-methylphenyl)amino]-9,10-anthracenedione, DG6). The new method uses ultra-performance liquid chromatography (UPLC) with a 1.7-µ particle size C-18 column, 0.1 M ammonium acetate and acetonitrile as eluants, and photodiode array detection. Six-point linear regression calibration curves had r<sup>2 </sup>values that ranged from 0.9974 to 0.9998. Recoveries of impurities ranged from 99 to 103%. Relative standard deviations ranged from 2.42 to 4.29%. Limits of detection based on the calibration results are 0.0067% for PT, 0.0246% for MHAQ, 0.0394% for DHAQ, and 0.0245% for DG6. Samples from 15 certified lots analyzed by the new UPLC method provided results that are comparable to those obtained by gravity elution column chromatography, thin-layer chromatography, and alkaline isooctane extraction. The new UPLC method determines all of the impurities in a single analysis, uses green technology by reducing organic waste generation, and saves time and labor.

Determination of organic impurities in D&C violet No. 2 by ultraperformance liquid chromatography

249th National Meeting (2015)

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