Optimization and evaluation of electrochemical generation of
volatile zinc hydride in a novel electrolytic cell
M.H. Arbab-Zavar a,*, M. Chamsaz a, A. Youssefi b, M. Aliakbari a
a Department on Chemistry, Faculty of Science, Ferdowsi University,
Mashhad, Iran
b Par-e-Tavous Research institute, Mashhad, Iran
Electrochemical hydride generation (EcHG) has been shown to be a suitable
alternative to the chemical HG as a sample introduction method in atomic
spectrometry. The EcHG of limited number of elements including As, Se, Sb, Bi, Ge,
Sn and Cd has coupled with different atomic spectrometric techniques [1- 4]. It would
be challenging and interesting to expand the EcHG to other hydride forming elements
(HFEs).
The electrolytic HG of another HFE, zinc, by electrochemical catholyte
variation EcHG method, described in details in our early publications for cadmium
[4, 5] was studied. The system consisted of a novel laboratory-made electrolytic cell
with lead-tin alloy cathode as electrolytic generator of molecular hydride or zinc
hydride that it was coupled with an atomic absorption spectrometer (AAS) equipped
with an electrically heated quartz tube atomizer (QTA) for the on-line determination of
the generated vapours. During applying constant electrolytic current the gaseous
products (hydrogen and volatile hydrides) were transferred to the heated GTA by Ar
carrier gas.
The influences of type of cathode materials, acids of catholyte and the salts
used as anolyte were investigated. Several instrumental factors affecting the
technique were evaluated using a two-level multivariate Plackett-Burman
experimental design with two replicates of 12 nonrandomized runs. The significant
parameters were optimized by univariate method. Under optimized conditions, the
analytical figures of merit of the procedure were determined. The calibration curve
was linear in the range of 25-300 ng mL-1 of zinc. The calibration sensitivity and the
concentration detection limit were 6.4x10-4 /(ng mL-1) and 11 ng mL-1, respectively.
The reproducibility (R.S.D.) for nine replicate analyses at 200 ng mL-1 of Zn was
determined to be 5.0%. The interferences from various ions were studied. The
accuracy of the method was verified by the determination of zinc in a spiked tap
water sample.
References
[1] F. Laborda, E. Bolea, J.R. Castillo, Anal. Bioanal. Chem. In press
[2] N.H. Bings, Z. Stefanka, S.R. Mallada, Anal. Chim. Acta 479 (2003) 203-214.
[3] E. Denkhaus, A. Golloch, X.-M. Guo, B. Huang, J. Anal. At. Spectrom. 16 (2001)
870-878.
[4] M.H. Arbab-Zavar, M. Chamsaz, A. Youssefi, M. Aliakbari, Anal. Chim. Acta 546
(2005) 126-132.
[5] M.H. Arbab-Zavar, M. Chamsaz, A. Youssefi, M. Aliakbari, Anal. Chim. Acta 576
(2006) 215-220.