Quantitative analysis of Roussin red methyl ester in pickled vegetables.

In a study of the etiological factors in esophageal cancer, Roussin red methyl ester was isolated and identified in pickled vegetables of Linxian County, North China, where there is a high incidence of esophageal cancer. In this paper, a method is described for quantitative analysis of Roussin red methyl ester in pickled vegetables by gas chromatography-high-resolution mass spectrometry single-ion monitoring. The content of Roussin red methyl ester in pickled vegetables from Linxian has been found to be 0.1 to 4.5 mg/kg, and that from Beijing is below 0.005 mg/kg, which is the detection limit of the analytical method used. The marked difference between the contents might be one of the possible reasons for the difference in esophageal cancer incidence between the two regions.