PRECONCENTRATION OF BERYLLIUM ON THE OUTER-MEMBRANE OF ESCHERICHIA-COLI AND PSEUDOMONAS-PUTIDA PRIOR TO DETERMINATION BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY
Lc. Robles et Aj. Aller, PRECONCENTRATION OF BERYLLIUM ON THE OUTER-MEMBRANE OF ESCHERICHIA-COLI AND PSEUDOMONAS-PUTIDA PRIOR TO DETERMINATION BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY, Journal of analytical atomic spectrometry, 9(8), 1994, pp. 871-879
A rapid, simple and selective preconcentration method involving retent
ion of the analyte on the outer wall of Escherichia coli and Pseudomon
as putida has been developed. Several factors affecting the retention
of beryllium by the outer membrane of bacterial cells were optimized.
This procedure was used to preconcentrate trace amounts of beryllium p
rior to determination by electrothermal atomic absorption spectrometry
. Both batch and immobilization techniques for the two bacteria were c
ompared, but the former methods showed better analytical capabilities.
Beryllium ions are easily retained on the outer membrane at pH 6-9 fo
r E. coli and pH 3-10 for P. putida. The bacterial mass that retained
the beryllium was centrifuged and dispersed in 3.5 mol l-1 nitric acid
. The resulting slurry was introduced directly into the graphite tube.
The best analytical figures of merit were obtained for E coli using a
slurry sampling technique with a sensitivity and detection limit of 0
.015 and 0.05 ng ml-1, respectively, for the platform atomization of b
eryllium in the absence of a chemical modifier. No interferences from
the main major and minor ions of environmental interest were found. Th
e proposed method was applied to the determination of beryllium in an
environmental reference material.