Separation of a Newly Identified Contaminant from Commercial 4,5,6,7-Tetrachlorofluorescein by pH-Zone-Refining Countercurrent Chromatography

A. Weisz Office of Cosmetics and Colors, US Food and Drug Administration, Washington, DC, 20204, USA

D. Andrzejewski Office of Scientific Analysis and Support, US Food and Drug Administration, Washington, DC, 20204, USA

R. J. Highet Laboratory of Biophysical Chemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA

Y. Ito Laboratory of Biophysical Chemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA

Abstract

A 5-g sample of commercial 4,5,6,7-tetrachlorofluorescein (TCF) was subjected to pH-zone-refining countercurrent chromatography to separate an unidentified contaminant present in all TCF batches obtained from four different suppliers. The separated contaminant (44 mg) was characterized by ¹H- and ¹³C nuclear magnetic resonance spectrometry and negative ion chemical ionization mass spectrometry as a new seven-membered lactone TCF isomer with the structure 11,12,13, 14-tetrachloro-3, 14b-dihydroxy-[2]-benzoxepino- [3,4,5-kl]-xanthene-10(14bH)-one.

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Separation of a Newly Identified Contaminant from Commercial 4,5,6,7-Tetrachlorofluorescein by pH-Zone-Refining Countercurrent Chromatography

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Separation of a Newly Identified Contaminant from Commercial 4,5,6,7-Tetrachlorofluorescein by pH-Zone-Refining Countercurrent Chromatography

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