Two-step coprecipitation method for differentiating chromium species in water followed by determination of chromium by neutron activation analysis

Speciation of Chromium by Adsorptive Stripping Voltammetry Using Pyrocatechol Violet

“…for Cr III and Cr VI respectively. In order to check these results the determination was also carried out using two classical methods of univariate calibration using two different complexes DTPA and PCV [8,9,12], although the use of these complexes only allowed us to obtain the total amount of chromium When we attempted to analyze the sample of water using DTPA as complexing agent no analytical signal was obtained, for this reason a digestion procedure was carried out which involved UV radiation of 3 mL samples of sewage with 3 mL of H 2 O 2 and 100 mL of NH 4 OH, for about 4 h. In this phase of digestion, all the possible Cr III present is oxidized to form Cr VI , so that the concentration of chromium determined by this method is consequently, the total chromium content in the sample. The speciation of chromium according to the method described in [9] is …”

“…The majority of methods require separation and preconcentration stages to be carried out prior to the determination of low level concentrations of the individual species of chromium. Even techniques as sensitive as graphite furnace absorption spectrommetry (GFAAS) [3] or neutron activation analysis (NAA) [4] do not allow for analysis of chromium in all cases. These stages prior to pretreatment increase the time spent working and involve manipulation of the sample, which could possibly give rise to sources of error and contamination.…”

Preconcentration of trace elements in sea water with poly (acrylaminophosphonic - dithiocarbamate) chelating fiber for their determination by inductively coupled plasma mass spectrometry

“…Many preconcentration techniques have been proposed for the determination of metals in various environmental samples, including solvent extraction [2,3], ion exchange [4,5], coprecipitation [6,7] and sorption [8,9]. Recently, solid phase techniques have become increasingly popular in comparison with the more traditional liquid-liquid extraction methods [10].…”

A novel method for fast enrichment and monitoring of hexavalent and trivalent chromium at the ppt level with modified silica MCM-41 and its determination by inductively coupled plasma optical emission spectrometry

“…Depending on its oxidation state, the physiological effects of chromium on the biological systems are totally opposite. Chromium (III) is considered an essential element in mammals for the maintenance of glucose, lipid and protein metabolism, whereas Cr (VI) is considered to be a toxic material 1,3,4 , because of its ability to oxidize other species and its adverse impact on lung, liver and kidney. Owing to these two contrary effects, the precisely accurate determination of both species is essential.…”

“…For this purpose, various separation and pre-concentration methods such as liquid-liquid extraction 1,6 , coprecipitation 3,7 , ion exchange [8][9][10] and adsorption [11][12][13][14] have been developed. Sugiyama et al 6 determined trace elements including chromium in natural waters by ICP OES after preconcentration by dithiocarbamate extraction.…”