Determination of Illegally Used Chemical Dyes in the Chinese Herbal Medicine "Red Flower Oil".

Background: Red flower oil is a group of herbal medicinal liniments widely used in China and Southeast Asia. The color of red flower oil is adjusted to red or brownish-red by adding natural dyes.

Objective: The objective of this study is to identify and quantify the synthetic dyes illegally used in red flower oil.

Methods: Thirty-two batches of red flower oil (from nine manufacturers) were collected from different cities in China. High-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS) analysis was performed to identify the chemical dyes in the samples, and high-performance liquid chromatography-diode array detection (HPLC-DAD) was used to quantify the chemical dyes.

Results: Sudan I, Sudan IV, and Solvent Red 207 were detected in nine batches of preparations (from three manufacturers) with concentration ranges of 101.7-214.9 μg/mL for Sudan I, 24.0-41.0 μg/mL for Sudan IV, and 147.5-221.7 μg/mL for Solvent Red 207.

Conclusion: In present study, sudan I, sudan IV, and solvent red 207 were detected in red flower oil. The control of chemical dyes in food and drug should be further studied and not limited to sudan dyes.

Highlights: It is the first report about the detection of solvent red 207 in food and drug. The illegal use of those chemical dyes should be regarded as serious violation of good manufacturing practice (GMP) and might be dangerous for the patients.