Determination of anionic minerals in black and kombucha tea using ion chromatography

Abstract

A simple, rapid and accurate method for the determination of anionic minerals in tea brew has been developed. The quantitative determination of anions – fluoride, chloride, bromide, iodide, nitrate, phosphate and sulphate was accomplished by anion exchange chromatography with conductometric detection. A Metrosep Anion Dual 2 analytical column connected in series with a Metrosep RP guard column was used for anion separation. A solution containing a mixture of 1.3 mM Na2CO3 and 2 mM NaHCO3 was used as eluent. The method requires a simple sample clean-up procedure to remove the interfering organic components from the tea brew. The limit of detection for different anionic minerals were in the range 0.01–0.05 μg mL−1 and the relative standard deviation were in the range 4–6% for the overall method. The recovery of different anionic minerals added was in the range 95–106%. The method was applied to the determination of anions in black and kombucha tea.