Spectrofluorimetric determination of boron in plants with quinizarin-2-sulphonic acid

A simple and sensitive method for the determination of boron by spectrofluorimetry with quinizarin-2-sulphonic acid is proposed. The fluorescence intensity of the complex formed in concentrated sulphuric acid is developed in 15 min and there is no need for heating. The excitation wavelength is 522 nm and emission is measured at 578 nm. The detection limit is 6 ng ml–1. A study was made of the influence of several ions as potential interferents. The only interferences, produced by nitrate and fluoride, can be adequately eliminated. The method has been satisfactorily applied to the determination of boron in plants.