Determination of chromium in river waters by electrothermal atomic absorption spectrometry with preconcentration on a tantalum wire

Abstract

The preconcentration of chromium on tantalum wire followed by electrothermal atomic absorption spectrometry with a tungsten tube atomizer is described. The preconcentration is accomplished by adsorbing chromium on a tantalum wire. The optimal immersion time was 3 mm. The best pH for chromium adsorption was 3. Under optimal conditions, the detection limit was 15 pg mU1 (3 x SIN). The effects on the preconcentration of chromium by large amounts of contaminants were evaluated. Even though matrix elements existed in 10(3)-10(4)-fold excess in water, the chromium absorption signal was not affected by the matrix elements. The method with preconcentration on tantalum wire was applied to the determination of chromium in river water.

Electrothermal atomic absorption spectrometric determination of cadmium in environmental samples with niobium wire preconcentration method

“…The largest adsorption for Cd was obtained at pH 4, as illustrated in Figure 2. In our previous works [14][15][16][17][18]28,29], the suitable pHs for silver [16], gold [28] and nickel [29] and by adsorption onto tungsten were 3, 3, 5 and for chromium [14], antimony [15], lead [17], manganese [18] by adsorption onto tantalum were 3, 2, 4 and 9, respectively. In the case of tungsten wire by Wolff et al [12], the recommended pHs for cadmium, copper, lead and zinc were >6, >6, 1 and 4-6, respectively.…”

“…The immersion time of an adsorbent in the aqueous solution can affect the preconcentration of an analyte [14][15][16][17][18]. Therefore, the influence of the immersion time International Journal of Environmental Analytical Chemistry 1383 of the niobium wire on the absorbance for Cd was evaluated at pH 7.…”

“…Moreover, it would be considered that the physical adsorption and the interaction between the element cadmium and the niobium wire surface might also occur as the preconcentration mechanism. From the information in the literature [7][8][9][10][11][12][13][14][15][16][17][18][19][25][26][27][28][29], it is not clear which process is predominant for the adsorption of cadmium on the niobium wire. These processes are still being examined.…”

“…In the previous studies [14][15][16][17][18], preconcentration techniques by adsorption onto tungsten and tantalum wires have been developed for ETAAS with a tungsten tube atomizer. Antimony, chromium, silver, lead and manganese have been successfully determined in the environmental samples such as rain and river water with these methods.…”

Exploiting of the phenoxazine as first – ever use ligand in rapid spectrophotometric methods for the determination of chromium(VI) in environmental samples

“…Numerous solvent extraction procedures have been suggested for the determination of chromium [21,22], but these methods are lengthy, time consuming and lacks sensitivity due to much interference [23]. Besides, there are many instrumental methods such as ICP-MS [24,25], ICP-AES [26,27], and AAS [28,29], but they are disadvantageous in terms of cost and unavailable in some laboratories, while some of them such as AAS are often lacking in sensitivity and affected by matrix conditions of samples such as salinity. Although, the diphenylcarbazide [30][31][32] is considered the famous spectrophotometric reagent for the determination of hexavalent chromium, it suffers serious interferences from many cations namely, Fe(III), Mo(VI), Cu(II), and Hg(II) [30,33], and also the formed complex is stable for only 30 min in the presence of a phosphate buffer [34].…”