Determination of beryllium by electrothermal atomic absorption spectrometry using tungsten surfaces and zirconium modifier.

Electrothermal atomization of beryllium from graphite and tungsten surfaces was compared with and without the use of various chemical modifiers. Tungsten proved to be the best substrate, giving the more sensitive integrated atomic absorption signals of beryllium. Tungsten platform atomization with zirconium as a chemical modifier was used for the determination of beryllium in several NIST SRM certified reference samples, with good agreement obtained between the results found and the certified values. The precision of the measurements (at 10 microgL(-1)), the limit of detection (3sigma), and the characteristic mass of beryllium were 2.50%, 0.009 microgL(-1) and 0.42 pg, respectively.

Determination of cadmium in biological and environmental samples by slurry electrothermal atomic absorption spectrometry.

The retention of cadmium by the bacteria Escherichia coli and Pseudomonas putida was optimized in order to develop a rapid and selective preconcentration method for cadmium from biological and environmental samples prior to determination by electrothermal atomic absorption spectrometry. Living and lyophilized cells for both bacteria were used, but the method using dead cells shows better analytical capabilities. Cadmium from aqueous solutions is easily retained on the outer membrane of both bacteria in the pH range 4-10, although the selected working pHs for E. coli and P. putida were 5 and 9, respectively. Cadmium retained by the bacteria was dispersed in 3.5 M nitric acid and the slurry was introduced directly into the graphite tube. The best sensitivity and detection limit were obtained for E. coli (0.03 ng ml(-1) and 0.04 ng ml(-1) respectively, in the absence of any chemical modifier). A strong spectral interference from nickel chloride was found and methods to overcome it were developed. The proposed extraction procedure was tested by the determination of cadmium in different standard biological and environmental samples.

Flame atomic absorption spectrometric method for the determination of beryllium in natural waters after separation with N-benzoyl-N-phenylhydroxylamine.

A procedure for the determination of beryllium in natural waters is proposed. A solvent extraction step was performed in order to overcome interferences and isolate beryllium before it was atomized by direct nebulization of the organic phase in a dinitrogen oxide-acetylene flame. N-Benzoyl-N-phenylhydroxylamine was used as the extractant whilst isobutyl methyl ketone was the organic solvent. The effects of pH, amine concentration in the organic phase, shaking time, stability of the complex and nature of the extracted species were studied. The detection limit and linear response range are 2 ng ml-1 and 0-1.0 microgram ml-1, respectively. The result obtained for a standard reference material compared well with the quoted value.