Identification of 2-bromo-3,4,5,6-tetrachloroaniline and its quantification in the color additives D&C Red Nos. 27 and 28 (phloxine B) using solid-phase microextraction and gas chromatography-mass spectrometry

The present work describes (a) the identification and characterization of a contaminant, 2-bromo-3,4,5,6-tetrachloroaniline (2BTCA), in the color additives D&C Red Nos. 27 and 28 (phloxine 13) and (b) the determination of the extent and level of 2BTCA contamination in certified lots of these colors. For these purposes, 213TCA (a compound not previously reported in the literature) and its positional isomer 4-bromo-2,3,5,6-tetrachloroaniline (4BTCA) were synthetically prepared. 4BTCA was used as the internal standard for the quantification of 213TCA in the colors. Test portions from 35 certified lots of D&C Red Nos. 27 and 28 were analyzed for 213TCA using a solid-phase microextraction-GC-MS method. Those lots were submitted for certification by both domestic (seven) and foreign (four) manufacturers during the past 4 years. Of the test portions analyzed, 22 (62.9%) contained 213TCA in amounts ranging from 0.15 to 435.7 ppm with an average value of 131.7 ppm. The remaining 13 (37.1%) test portions contained no detectable 213TCA or less than 0.01 ppm, which is the limit of quantification of the present method. The analyses revealed substantial differences in the level of 213TCA across lots from the same manufacturer as well as among different manufacturers. The wide range of 213TCA levels found in the analyzed lots suggests that the presence of 2BTCA in D&C Red Nos. 27 and 28 may be avoided or significantly reduced during the manufacturing process. A direct correlation was observed between the presence of 213TCA and that of 3,4,5,6-tetrachlorophthalic acid in analyzed batches of D&C Red Nos. 27 and 28. A chemical pathway that could explain the presence of 2BTCA in these color additives, and ways to avoid its formation, are also proposed. Published by Elsevier B.V.