Preconcentration and Determination of Chromium Species Using Octadecyl Silica Membrane Disks and Flame Atomic Absorption Spectrometry

Abstract

A novel and selective method for the fast determination of trace amounts of chromium species in water samples has been developed. The procedure is based on the selective formation of chromium diethyldithiocarbamate complexes at different pH in the presence of Mn(II) as an enhancement agent of chromium signals followed by elution with organic eluents and determination by atomic flame absorption spectrometry. The maximum capacity of the employed disks was found to be (396±3) µg and (376±2) µg for Cr(III) and Cr(VI), respectively. The detection limit of the proposed method is 49 and 43 ng•L -1 for Cr(III) and Cr(VI), respectively. The proposed method was successfully applied for determination of chromium species Cr(III) and Cr(VI) in different water samples.

Preconcentration and determination of Mercury(II) from natural water and milk sample by Histidine functionalized multi-walled carbon nanotubes (MWCNTs-His)

“…The method developed was simple, reliable, and precise for determining Hg(II) in water. Also, the proposed method was free of interference compared to conventional procedures to determine Hg(II) (Choi and Choi, 2003;Moghimi, 2006;Tuzen et al, 2009a). The method can be successfully applied to the separation and determination of Hg(II) in binary mixtures.…”

“…Ultra pure organic solvents were obtained from Merck Chemical Company, Darmstat, Germany, and high Purity deionized water was used throughout the experiments and 3-chloro propyl trimethoxysilane was received from Aldrich Chemical, USA. Organic solvents were dried according to conventional methods (Moghimi et al, 2006). For all solutions double distilled water was used and the buffer solutions were prepared from 1.0 M sodium acetate to which different volumes of 1.0 M HCl; HNO3 were mixed.…”

“…The metal capacity values determined in µmol g −1 for the MWCNTs-His in different buffer solutions were studied to evaluate the pH effect of metal ion on the extractability of (Moghimi et al, 2006).…”

“…Second subject is the strong affinity of the MWCNTs-His phase for extraction and removal of Hg(II) from aqueous solution compared to other tested metal ions, as shown by the higher µmol g −1 values by MWCNTs-His phases (Moghimi, 2006). This behavior of MWCNTs-His-loaded sulfurcontaining compounds for selective extraction and removal of Hg(II) from aqueous and natural water sample is well documented (Mahmoud, 1998(Mahmoud, , 1999 and reported based on different governing rules (Tong et al, 1990).…”

“…Both drinking tap water and DDW (2 L) were spiked with 20 pg ml −1 of Hg(II). Several pre-concentration reagents are well known and extensively examined for desorption of the bound metal ions from the surface of the stationary phase and these include mainly, hydrochloric and nitric acid, thiourea HCl (Shamsipur et al, 2005) as well as ethylenediaminetetraacetic acid (Moghimi, 2006). However, some of these reagents are usually characterized by adsorption on the surface of MWCNTsHis which lead to severe change in the nature of packing material as well as non reproducible results if the column used in future applications.…”