Speciation chromium

Veecoutere K, and Cornelis R (1995) Chromium speciation in environmental and biological samples. In Quality Assurance for Environmental Analysis, Qubvauviller Ph, Maiee EA and Geiepink B, eds. pp 195-213. Elsevier, Amsterdam. 

Other applications of supported liquid membranes have been related to metal speciation. For example, recently a system for chromium speciation has been developed based on the selective extraction and enrichment of anionic Cr(VI) and cationic Cr(III) species in two SLM units connected in series. Aliquat 336 and DEHPA were used respectively as carriers for the two species and graphite furnace atomic absorption spectrometry used for final metal determination. With this process, it was possible to determine chromium in its different oxidation states [103]. 

On-line anion exchange LC/ICP-MS methods for selenium and chromium speciation have been published [30], In studies of selenium speciation in environmental samples LC/ICP-MS and LC/ ESI-MS methods have been used for the determination of both inorganic and organic selenium species [43]. For the determination of methyl selenide, strong anion exchange and RP chromatography have been employed [43], while for the determination of seleno-aminoacids, IP RP chromatography with on-line detection based on ICP-MS has been successfully employed [44],... 

Neubauer, K. R., M. V. Johnston, and A. S. Wexler, Chromium Speciation in Aerosols by Rapid Single-Particle Mass Spectrometry, Int. J. Mass Spectrom. Ion Processes, 151, 77-87 (1995). 

Elderfield, H., 1970. Chromium speciation in seawater. Earth Planet. Sci. Lett., 9 10-16. 

Fodor and Fischer [84] have investigated problems of chromium speciation in soils. When employing spectrophotometric detection, only a method based on the diphenylcarbazide reaction was found suitable for chromium speciation analysis. 

Prokisch et al. [85] described a simple method for determining chromium speciation in soils. Separation of different chromium species was accomplished by the use of acidic activated aluminium oxide. Polarographic methods have been applied in speciation studies on chromium(VI) in soil extracts [86]. Mi-lacic et al. [88] have reviewed methods for the determination of chromium(VI) in soils. 

Marques [94] has reviewed literature on chromium speciation in soils. The determination of chromium is also discussed under Multi-Metal Analysis of Soils in Sect. 2.55. 

Stewart, I.I. and Horlick, G. (1996) Investigation into chromium speciation by electrospray mass spectrometry. J. Anal. At. Spectrom., 11, 1203-1214. 

Szulczewski, M.D., Helmke, Ph.A. and Bleam, W.F. (1997) Comparison of XANES analyses and extractions to determine chromium speciation in contaminated soils. Environ. Sci. Technol., 31, 2954. 

Difficulties have been observed in the preservation of samples for speciation of chromium. Chromium speciation in seawater was determined on board ship shortly after samples had been collected (Abollino et at., 1991). Some samples were frozen, and analysed later in a laboratory. However, significantly lower concentrations of Crvl were observed in these latter samples. Thus, sea-going analytical methods for the determination of Crm and total chromium are of particular importance (Mugo and Orians, 1993). The volatile trifluoroacetyl-acetone derivative of Crm was formed and then concentrated by extraction into toluene. Chromium was determined by means of a gas chromatograph equipped with an electron capture detector. Total chromium was determined as Cr111 after reduction. The detection limits were 0.062 and 0.255 nmol dm 3 total chromium. A useful method was described for sampling natural water in the field, and for the preservation of Crm and Crvl species for subsequent analyses in a laboratory (Cox and McLeod, 1992). Water samples were drawn through small columns packed with activated alumina, which had been prepared previously. Chromium species were retained on the columns. 

According to the review by Marques et al.,75 the most frequent pretreatment used for chromium speciation is complex formation. Extraction processes are frequently used after complex formation to extract the complexes formed prior to UV-VIS detection. Recently, the simultaneous determination of Cr(III) and Cr(VI) using an in-capillary reaction, CE separation, and chemiluminescence detection was reported with LODs (Table 7.2) for Cr(III) and Cr(VI) of 0.6 and 8 pM, respectively.32... 

In the 1980s, an analytical technique was developed for the study of chromium speciation in natural waters based on the atomization of electrodeposited species on graphite tubes.79 Two independent automated platforms consisting of an ultraviolet (UV) on-line unit and a chelation/preconcentration/... 

Emstberger, H., H. Zhang, and W. Davison. 2002. Determination of chromium speciation in natural systems using DGT. Anal. Bioanal. Chem. 373 873-879. 

Bobrowski, A., B. Bas, J. Dominik, et al. 2004. Chromium speciation study in polluted waters using catalytic adsorptive stripping voltammetry and tangential flow filtration. Talanta 63 1003-1012. 

Marques, M.J., A. Salvador, A. Morales-Rubio, and M. De la Guardia. 2000. Chromium speciation in liquid matrices A survey of the literature. Fresenius J. Anal. Chem. 367 601-613. 

Batley, G.E. and J.P Matousek. 1980. Determination of chromium speciation in natural waters by electrodeposition on graphite tubes for electrothermal atomization. Anal. Chem. 52 1570-1574. 

Cox XB, Linton RW, Butler FE. 1985. Determination of chromium speciation in environmental particles. Multitechnique study of ferrochrome smelter dust. Environ Sci Technol 19 345-352. 

Chromium speciation by using anion-exchange chromatography has also received much attention in recent years because the element is both essential to humans and toxic in large doses [62-66]. Cr (III) and Cr (VI) may be separated by... 

Chromium speciation has also been successfully achieved by using SFC [99]. Two p-ketonate chromium compounds and an organochromium dimer were separated initially, using C02 as the mobile phase. However, as a result of an isobaric interference at m/z 52 (the major chromium isotope) from the formation of 40Ar12C+, nitrous oxide was used instead. 

Another species of interest in drinking water analysis is Cr (VI), considerably more toxic than Cr (III) and classified as carcinogenic to humans. Chromium speciation in water has been carried out by HPLC-ICP-MS, using both IEC and RPIPC (see Table 8.3). 

Djane N-K, Ndung u K, Johnson C, Sartz H, Tdmstrdm T, and Mathiasson L. Chromium speciation in natural waters using serially connected supported Uquid membranes. Talanta 1999 48 1121-1132. 

Diphenylcarbazide was also applied in the determination of chromium speciation in silicon [90], and after preliminary separation of Cr(III) and Cr(VI) by HPLC [91]. 

Djane, N. K., Ndung u, K., Johnsson, C., Sartz, H., Tomstrom, T., Mathiasson, L. (1999). Chromium speciation in natural waters using serially connected supported hquid membranes. Talanta, 48, 1121-32. 

Analytical Methods Chromium Speciation (see Party, Chapter 3)... 

Because hexavalent chromium is the toxic form of the metal, a number of researchers have focused on methods for distinguishing between chromium(III) and chromium(VI). Analytical techniques for chromium speciation in liquid matrices were reviewed recently (Marques etal. 2000). There are concerns about chromium as a drinking water contaminant in some areas, and samples most frequently analyzed were standard waters, potable waters and wastewaters. 

The methodologies used for chromium speciation in liquid samples are very diverse preconcentration on different types of columns, chemical reactions such as complexation or oxidation-reduction, and other separation procedures have been used and will be reviewed briefly below. These pretreatments with subsequent atomic spectrometric determination allow good limits of detection and recoveries for samples with low concentrations of chromium (Comelis 1996). Polarography is also suitable for the determination of chro-... 

Chromium speciation by anion-exchange high-performance liquid chromatography with both inductively coupled plasma atomic emission spectroscopic and inductively coupled plasma mass spectrometric detection. J Chromatogr A712 311-320. 

Farmer JG, Thomas RP, Graham MC, Geelhoed JS, Lumsdon DG and Paterson E (2002) Chromium speciation and fractionation in ground and surface waters in the vicinity of chromite ore processing residue disposal sites. J Environ Monit 4 235-243. 

Kieber RJ, Willey JD and Zvalaren SD (2002) Chromium speciation in rainwater temporal variability and atmospheric deposition. Environ Sci Technol 36 5321-5327. 

Chromium speciation in the vadose zone beneath the Hanford S-SX nuclear waste tank farm. Chromium is present in relatively high concentrations in the high-level nuclear waste tanks at Hanford, WA and has been found at concentrations as high as... 

Zachara JM, Ainsworth CC, Brown GE Jr, Catalano JG, McKinley JP, Oafoku O, Smith SC, Szecsody JE, Traina SJ, Warner JA (2002) Chromium speciation and mobility in a high level nuclear waste vadose zone plume. Geochim Cosmochim Acta (submitted)... 

J. Ruz, A. Rios, M. D. Luque de Castro, and M. Valc rcel, Flow-Injection Configurations for Chromium Speciation with a Single Spectrophotometric Detector. Anal. Chim. Acta, 186 (1986) 139. 

Some of the difficulties in the unbiased determination of certain trace elements in biological materials may be due to problems of speciation. The range of complex organo-metallic species that can be found in nature is very wide (Frausto da Silva and Williams, 1991). In carrying out an analysis for a particular element in any type of biological fluid or tissues, major assumptions are made concerning the precise chemical composition of element species present. Different analytical techniques will have different sensitivities towards particular element species. Much of the early understanding of the special analytical problems posed by element speciation comes from studies of arsenic (Buchet et al., 1980 Buchet et al., 1981) and mercury (Clarkson, 1983). Problems with other metals remain to be resolved and may require considerable analytical sophistication such as in the analysis of chromium speciation (Urasa and Nam, 1989). 

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