Simultaneous speciation of chromate, arsenate, molybdate and vanadate in alkaline samples by HPLC-ICP-MS at different concentration levels of vanadate

Abstract

Flay ash, cement and electric arc furnace (EAF) dust are frequently mixed in building composites. From them, chromium (Cr), arsenic (As), molybdenum (Mo) and vanadium (V) may be leached. Concentrations of V in leachates may be significantly higher than those of Cr, As and Mo, making simultaneous speciation analysis particularly difficult. In this work, a high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) procedure was used for simultaneous speciation of chromate, arsenate, molybdate and vanadate. First, the behaviour of Cr, As, Mo and V species in different oxidation states was studied during their separation under acidic (pH 5) and alkaline (pH 12) conditions. At alkaline pHs chromate, arsenate, molybdate and vanadate were simultaneously separated and eluted at retention times from 390 to 450 s, 230 to 270 s, 340 to 430 s and 270 to 380 s, respectively and detected on-line by ICP-MS, recording m/z 52, 75, 95 and 51, respectively. When V species were leached in significantly higher concentrations than Cr, Mo and As, their detection was possible at the low abundance (0.25%) 50 V isotope, which is also the mass of the 50 Cr isotope (abundance 4.345%), due to selective separation between V and Cr species. Good repeatability of measurement (RSD better than AE3.0%) and quantitative elution of elemental species (column recoveries 99-105%) were obtained. Finally, the procedure was applied in the simultaneous speciation analysis of chromate, arsenate, molybdate and vanadate in highly alkaline aqueous leachates from composites consisting of fly ash, cement and EAF dust that contained a wide range of concentrations of vanadate.

Atomic Spectrometry Update – a review of advances in environmental analysis

“…When U-rich particles had been located, LA-ICP-MS was used for IRA. The determined 235 U/ 238 38 to be reliable, accurate (spike recoveries in the range 98-102%), precise (repeatability <3%) and fast (chromatographic separations in 10 minutes).…”

“…Ellis et al 274 were able to analyse a single sanidine grain by splitting large crystals into up to four fragments. One split was used to perform high-precision 40 A recent study demonstrated 276 that cosmogenic 38 Ar exposure dating of Ca-rich minerals could be a valuable new dating tool and provided the first terrestrial cosmochrons using the 38 Ar isotope system. Previous application of this dating technique to terrestrial samples had been considered impracticable because of the high atmospheric 38 Ar background on Earth.…”

“…One split was used to perform high-precision 40 A recent study demonstrated 276 that cosmogenic 38 Ar exposure dating of Ca-rich minerals could be a valuable new dating tool and provided the first terrestrial cosmochrons using the 38 Ar isotope system. Previous application of this dating technique to terrestrial samples had been considered impracticable because of the high atmospheric 38 Ar background on Earth. A new generation MC noble gas mass spectrometer enabled very precise analyses of cosmogenic 36 Ar and 38 Ar abundances in irradiated terrestrial pyroxene and apatite from Australia to be made.…”

“…Previous application of this dating technique to terrestrial samples had been considered impracticable because of the high atmospheric 38 Ar background on Earth. A new generation MC noble gas mass spectrometer enabled very precise analyses of cosmogenic 36 Ar and 38 Ar abundances in irradiated terrestrial pyroxene and apatite from Australia to be made. The 38 Ar/ 36 Ar ratios could be measured with a precision of ±0.30% (1SD).…”

“…The measured exposure age overlapped, within uncertainty, with the known 40 Ar/ 39 Ar eruption age of the sampling site. It was concluded that cosmogenic 38 Ar exposure dating on irradiated Ca-rich but Cl-free terrestrial minerals was potentially a valuable addition to the range of tools for dating cosmogenic exposure and examining geological surface processes on timescales of a few Ma.…”