Determination of tellurium at ultratrace levels in drinking water by on-line solid phase extraction coupled to graphite furnace atomic absorption spectrometry

J. PEDRO; J. STRIPEIKIS; A. BONIVARDI; M. TUDINO

SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY

ELSEVIER

Año: 2008 vol. 63 p. 86 - 91

0584-8547

In this paper, two time-based flow injection (FI) separation pre-concentration systems coupled to graphite furnace atomic absorption spectrometry (GFAAS) for tellurium determination are studied and compared. The first alternative involves the pre-concentration of the analyte onto Dowex 1X8 employed as packaging material of a micro-column inserted in the flow system. The second set-up is based on the co-precipitation of tellurium with La(OH)3 followed by retention onto XAD resins. Both systems are compared in terms of limit of detection, linear range, RSD%, sample throughput, micro-columns lifetime and aptitude for fully automatic operation. The features of the Dowex system are: 37 % efficiency of retention and an enhancement factor of 42 for a pre-concentration time of 180 seconds (sample flow rate = 3 ml.min-1) with acetic acid elution volumes of 80 ml.  The detection limit (3s) is 7 ng.l-1 and the relative standard deviation (n=7, 200 ng.l-1 ) is 5.8 %. The analytical performance of the XAD system is: 72 % efficiency of retention and an enhancement factor of 25 for a pre-concentration time of 180 seconds (sample flow rate = 3 ml.min-1) with nitric acid elution volumes of 300 ml.  The detection limit is 66 ng.l-1 and the relative standard deviation (n=7, 200 ng.l-1 ) is 8.3 %. Applications to the determination of tellurium in tap water and the validation of the analytical methodology employing SRM 1643e as certified reference material are shown.