Simultaneous speciation of arsenic, selenium, and chromium: species stability, sample preservation, and analysis of ash and soil leachates

Abstract

An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 °C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present, but typically at low levels.

Study on multielemental speciation analysis of Cr(VI), As(III) and As(V) in water by advanced hyphenated technique HPLC/ICP-DRC-MS. Fast and reliable procedures

“…To date, limited papers report on the use of DRC in multielemental speciation analysis. Wolf et al applied nitrogen as a reaction gas in the DRC to eliminate interferences in multielemental speciation analysis of As(III), As(V), Cr (VI), Cr(III), Se(IV) and Se(VI) [15]. Methane, as a reaction gas, was used by Tsoi and Leung in determination of As, Cr and Se species in estuarine waters [16].…”

“…In case of reversed-phase ion-pair chromatography, tetrabutylammonium hydroxide and ethylenediaminetetraacetic acid (di-potassium salt) are often used as a mobile phase components [15]. In presented work, ammonium dihydrogen phosphate and ammonium nitrate were selected for the mobile phase.…”

“…Multielemental speciation studies, a successor of well-studied single element speciation, is recently gaining more attention despite difficulties resulting from chromatographic separation [5]. The following papers on the multielemental speciation in different matrices have been reported, for: As, Se [4,6,7]; As, Cr [5,[8][9][10]; As, Sb [11,12]; Cr, Se [13]; As, Se, Cr [14][15][16]; As, Sb, Se [17][18][19]; As, Se, Sb, Te [4]; As, Se, Cr, Mo [20]. The key issue in multielemental speciation analysis is the selection of such separation and determination conditions, which, for individual species of several elements, simultaneously ensure: (i) retention of each of the analytes on a chromatographic column and its elution in a reasonable analysis time; (ii) complete separation of analytical signals; (iii) symmetrical analytical signals; (iv) stability of the different species throughout the whole analytical procedure; (v) elimination of potential interferences; (vi) sufficiently low detection limits.…”

“…Therefore, multielemental speciation analysis requires in-depth knowledge of the behavior of different species and of the solution of the analytical problems associated with the selection of the optimal conditions for all analytes. Nevertheless, because multielemental speciation analysis allows the determination of several element species during one analysis, it ensures higher analyte stability, reduces the time of analysis, and decreases the volume of sample and reagents [15].…”

Determination of Elemental Impurities in Acyclovir Ointment and Raw Materials Using Microwave Acid Digestion (MW-AD) and ICP-MS

“…However, the accuracies which some isotopes are determined may be compromised by spectral and non-spectral interferences. [12][13][14] Different strategies have been employed to reduce such spectral interferences, including the use of a collision and reaction interface (CRI), 15 internal standards, 16 mathematical correction equations, 17 dynamic reaction cells (DRC), 18 and kinetic energy discrimination (KED). 19 The aim of this study was to optimize a microwave acid digestion (MW-AD) procedure for simultaneous determination of As, Cu, Cr, Ni, Pb and V by ICP-MS employing the standard mode, which allows the ICP-MS to be operated with the cell turned off, and second ICP-MS determination method evaluated was the KED mode, in acyclovir ointment and their manufacturer products disodium edetate, acyclovir API, non-ionic emulsifying wax, and methylparaben.…”