A reversed-phase liquid chromatographic method was developed to determine parts-per-million and higher levels of Sudan I, 1-(phenylazo)-2-naphthalenol, in the disulfo monoazo color additive FD&C Yellow No. 6 and in a related monosulfo monoazo color additive, D&C Orange No. 4.
Sudan I, the corresponding unsulfonated monoazo dye, is a known impurity in these color additives. The color additives are dissolved in water and methanol, and the filtered solutions are directly chromatographed, without extraction or concentration, by using gradient elution at 0.25 mL/min.
Calibrations from peak areas at 485 nm were linear. At a 99 confidence level, the limits of determination were 0.008 g Sudan I/mL (0.4 ppm) in FD&C Yellow No. 6 and 0.011 g Sudan I/mL (0.00011) in D&C Orange No. 4. The confidence intervals were 0.202 0.002 g Sudan I/mL (10.1 0.1 ppm)
near the specification level for Sudan I in FD&C Yellow No. 6 and 20.0 0.2 g Sudan I/mL (0.200 0.002) near the highest concentration of Sudan I found in D&C Orange No. 4. A survey was conducted to determine Sudan I in 28 samples of FD&C Yellow No. 6 from 17 international manufacturers
over 3 years, and in a pharmacology-tested sample. These samples were found to contain undetected levels (16 samples), 0.59.7 ppm Sudan I (0.010.194 g Sudan I/mL in analyzed solutions; 11 samples including the pharmacology sample), and 10 ppm Sudan I (0.2 g Sudan I/mL; 2 samples). Analyses
of 21 samples of D&C Orange No. 4 from 8 international manufacturers over 4 years found Sudan I at undetected levels (8 samples), 0.0005 to <0.005 Sudan I (0.05 to <0.5 g Sudan I/mL in analyzed solutions; 3 samples, including a pharmacology batch), 0.005 to <0.05 Sudan I (0.5
to <5 g Sudan I/mL; 9 samples), and 0.18 Sudan I (18 g Sudan I/mL; 1 sample).
Document Type: Research Article
U.S. Food and Drug Administration, Office of Cosmetics and Colors, HFS-106, 5100 Paint Branch Pkwy, College Park, MD 20740.
Publication date: September 1, 2007
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