Color additives in foods, drugs, cosmetics, and medical devices are regulated by the U.S. Food and Drug Administration (FDA). All color additives must be pre-approved and listed in the Code of Federal Regulations (CFR) before they may be used in FDA-regulated products. D&C Red No. 6 (R6) is the disodium salt of 3-hydroxy-4-[(4-methyl-2-sulfophenyl)azo]-2-naphthalenecarboxylic acid, and D&C Red No. 7 (R7) is the calcium salt of the same dye anion. D&C Yellow No. 10 (Y10) is a mixture of the sodium salts of the mono- and disulfonic acids of 2-(2-quinolinyl)-1H-indene-1,3(2H)-dione. Lakes are insoluble pigments formed by precipitating a dye (straight color) onto an insoluble substratum such as barium sulfate or rosin.  The CFR requirements for R6 and R7 include a specification for p-toluidine of not more than 15 ppm. Y10 has a specification for 2-(2-quinolinyl)-1H-indene-1,3(2H)-dione (which is certifiable as D&C Yellow No. 11) of not more than 4 ppm. Currently FDA uses chloroform extraction techniques and high-performance liquid chromatography with photodiode array (PDA) detection for determining the two organic impurities in the straight colors. The lakes are not analyzed. The present work describes two solid phase extraction techniques combined with ultra-performance liquid chromatography and PDA detection for determining p-toluidine in R6 and R7 straight colors and lakes and 2-(2-quinolinyl)-1H-indene-1,3(2H)-dione in Y10 straight colors and lakes.

Determination of organic impurities in D&C Red No. 6, D&C Red No. 7, and D&C Yellow No. 10 using solid phase extraction and ultra-performance liquid chromatography

248th National Meeting (2014)

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