Aluminium and Its Complexes in Teas and Fruity Brew Samples, Speciation and Ions Determination by Ion Chromatography and High-Performance Liquid Chromatography–Fluorescence Analytical Methods

Abstract

The paper presents results of aluminium determination in samples of black and fruit teas. Total aluminium concentration was determined along with the concentration of aluminium in a cup of tea in tea samples in two price groups (>1€ and <1€). Based on the conducted study, no differences were found in aluminium concentration in black and fruit teas depending on the price group. Developed ion chromatography method was applied to determine inorganic and organic ions in tea samples, especially those which may form complexes with aluminium: fluoride, sulphate, oxalate and citrate ions. Analysis by this method using ion chromatography allowed for the determination of 12 anions: F−, HCOO−, CH3COO−, NO2−, Br−, NO3−; Cl−, CH2(COO)22−, SO42−, C2O42−, PO43− and C3H5O(COO)33− in the time of 40 min. Speciation analysis of aluminium was performed in optimised HPLC-fluorescence analytical system (with Lumogallion as a post-column reagent). It was observed that organic aluminium complexes are quickly degraded to form Al3+ which is the reason why speciation analysis in tea samples does not provide the full image of speciation distribution. Nevertheless, this developed method was successfully used in the determination of aluminium complexes with fluorides in tea samples.