Structural determination of four manufacturing impurities of D&C Red No. 33.

Authors :: Mazzola EP
Weisz A
Ridge DP
Donnelly SE
Zhang H
Gonzalez RM
Ackerman LK
Reese KL
Ridge CD
Source :: Magnetic resonance in chemistry : MRC [Magn Reson Chem] 2021 Nov; Vol. 59 (11), pp. 1107-1115. Date of Electronic Publication: 2021 Apr 27.
Publication Year :: 2021
Abstract: Four manufacturing impurities of D&C Red No. 33 isolated by counter-current chromatography were analyzed by NMR and ESI mass spectrometry. Three of these impurities were reported previously with minimal details of structural determination. All four are structurally related to the main component of the dye. The fourth exhibited an unusual discrepancy between the NMR structure and its chemical formula suggested by ESI-MS results. Structural determination and assignment of the main component and four impurities are discussed as well as resolution of the discrepancy between the NMR and ESI-MS results of the fourth impurity.<br /> (Published 2021. This article is a U.S. Government work and is in the public domain in the USA.)