Quantitative determination of aluminium in tea by means of aluminium-27 nuclear magnetic resonance spectroscopy

Abstract

A method for determining the Al levels in tea leaf digests and tea infusions by means of ²⁷Al nuclear magnetic resonance (NMR) spectroscopy is described. Quantitative results down to 2.0 µg cm^–3 of Al in 0.5-cm^–3 acidified samples are readily obtainable in standard 5-mm NMR tubes. An acceptable quantitative determination is achieved by using an internal Al standard in a 1-mm capillary in conjunction with europium nitrate as a shift reagent.