Determination of Biogenic Amines in Pu-erh Tea with Precolumn Derivatization by High-Performance Liquid Chromatography

Abstract

In recent years, Pu-erh tea is popular around the world particularly due to its special health benefits. However, biogenic amines and their safe concentration in Pu-erh tea have not been fully studied. Therefore, we selected 28 kinds of Pu-erh tea from Yunnan Province, China, to determine methylamine, ethylamine, tryptamine, putrescine, cadaverine, histamine, tyramine, and spermidine contents. The analytical method involved an extraction with hydrogen chloride solution, precolumn derivatization of the amines with dansyl chloride, and subsequent analysis by high-performance liquid chromatography with UV detection. The relative correlation coefficient of this method was greater than 99%. Limits of detection were found between 0.2 and 1.1 μg/L. Recovery rates varied from 85 to 104%. Relative standard deviations were below 5%. Additionally, this study measured the concentrations of eight biogenic amines in Pu-erh tea using pure water extractions. The predominant amines in Pu-erh teas are methylamine, ethylamine, and tryptamine. The quantities of biogenic amines in the Pu-erh teas analyzed did not exceed established international safety limits for other food or beverages, and thus, Pu-erh teas appear to be safe to drink in this respect.