Effect of high salt concentrations on the determination of arsenic and selenium by flow injection hydride generation electrothermal atomic absorption spectrometry

Abstract

In the determination of arsenic and selenium by flow injection hydride generation ETAAS, the presence of up to 20% sodium chloride enhanced the signals for 20 mg l 21 arsenic and selenium by up to 28%. The enhancement was obtained with a variety of gas-liquid separators. A systematic study of the possible causes of the signal enhancement in the determination of selenium was undertaken, from which it was concluded that the effect originated in the processes responsible for the distribution of the hydrogen selenide between the solution and gas phases. Processes related to the transport of the analyte from the gas-liquid separator and the trapping of the analyte on the interior of the atomizer were not affected by the presence of dissolved salts. As sodium was found to be transported to the atomizer, it was deduced that aqueous aerosol was deposited in the atomizer, although the quantities were irreproducible. The enhancement could be eliminated by increasing the borohydride concentration. However, with the small volume gas-liquid separator, this latter approach was limited because of carry-over of liquid to the atomizer. The effect could be compensated for by adding up to 40% m/v of salt to the borohydride reagent.

Hydride generation atomic absorption spectrometry with insitu graphite tube trapping for the determination of Se (IV) and Se (VI) in baltic sea water samples

“…In order to improve the situation, a method of automatic introduction of the volatile hydrides into the atomiser should be examined. Nevertheless, it should be emphasised that even the simplest variant of determinations with the manual insertion of the capillary tube results in a relative standard deviation (RSD) in the range of 4.2 % -12.8 % for the concentrations of 2 ng/ml, and 0.1 ng/ml for determinations of the total content of selenium, which is acceptable for this concentration of selenium and comparable with the results reported by other authors [9,21,22].…”

Method for the determination of five toxicologically relevant arsenic species in human urine by liquid chromatography–hydride generation atomic absorption spectrometry

“…Matrix effects were determined comparing the slopes of calibration curves using matrix-matched standards with those applying pure solvent standards. Matrix effects >0% may be encountered in flow-injection systems in the presence of salts coeluting with arsenic species and hence reducing the solubility of the corresponding arsine [15]. The LODs of this method for As(III), As(V), MMA and DMA are comparable to those of most other studies or are even lower [1,5,7,[16][17][18].…”

Detection of volatile arsenic chloride species during hydride generation: a new prospectus

“…Arsenic chloride formation is fundamentally free from classical transition metal interferences. Ellis et al 14 studied the effect of NaCl on hydride generation efficiency and concluded that the increased salt concentration had a positive effect on the signal intensity of arsenic and selenium hydrides. Their explanation was based on the 'salting out' effect, to account for an improved gas-liquid separation efficiency.…”