Comparative determination of Ba, Cu, Fe, Pb and Zn in tea leaves by slurrysampling electrothermal atomic absorption and liquid sampling inductively coupled plasma atomic emission spectrometry

The comparative determination of barium, copper, iron, lead and zinc in tea leaf samples by two atomic spectrometric techniques is reported. At first, slurry sampling electrothermal atomization atomic absorption spectrometry (ETAAS) was applied. The results of Ba and Pb determination were calculated using the method of standard additions, and results of Cu, Fe and Zn from the calibration graphs based on aqueous standards. These results were compa red with the results obtained after microwave-assisted wet (nitric + hydroc hloric + hydrofluoric acids) digestion in closed vessels followed by induct ively coupled plasma-atomic emission spectrometric (ICP-AES) determination with the: calibration by means of aqueous standards. The exception was lead determined after a wet digestion procedure by ETAAS. The accuracy of the s tudied methods was checked by the use of the certified reference material T ea GBW-07605. The recoveries of the analytes varied in the range from 91 to 99% for slurry sampling ETAAS, and from 92.5 to 102% for liquid sampling I CP-AES. The advantages of slurry sampling ETAAS method are simplicity of sa mple preparation and very good sensitivity. Slurry sampling ETAAS method is relatively fast but if several elements must be: determined in one sample, the time of the whole microwave-assisted digestion procedure and ICP-AES d etermination will be shorter. However, worse detection limits of ICP-AES mu st also be taken into the consideration in a case of some analytes. (C) 199 8 Elsevier Science B.V. All rights reserved.