The determination of boron in tea and coffee by ICP–AES method

Abstract

A method for determination of boron by optical emission spectrometry with inductively coupled plasma has been suggested and sufficient experimental conditions have been found. The effect of the presence of Na, K, Mg, Ca, HCl, HNO 3 on the determination of boron has been studied. The internal standardisation as a correction technique was explored (In). The accuracy of the method was validated using the Chinese reference material GBW 07605 Tea. The efficiency of microwave digestion technique and hot water extraction was studied. The method was applied to the analyses of hot water extracts of tea and coffee samples. The mean extracted amount of boron ranged from 3.21±0.17 to 9.25±0.421 mg kg −1 in black teas; 3.54±0.12 to 5.52±0.15 mg kg −1 in green teas; 2.71±0.13 to 27.7±0.9 mg kg −1 in fruit teas; 13.3±0.4 to 21.3±0.7 mg kg −1 in instant coffees and from 7.57±0.26 to 17.5±0.5 mg kg −1 in ground roasted coffee beans.