Confirmation of lead aminocarboxylic complex formation using electrospray ionization mass spectrometry and speciation by anion-exchange chromatography coupled with ICP-MS

Inductively coupled plasma mass spectrometry (ICP-MS) and electrospray ionization mass spectrometry (ESI-MS) were used as complementary techniques to provide element and molecular information for aminocarboxylic lead species including [Pb(NTA)]¹⁻, [Pb(HEDTA)]¹⁻, [Pb(EDTA)]²⁻ and [Pb(DTPA)]³⁻. ESI-MS was used to initially confirm the formation of lead aminocarboxylic complexes in solution and subsequently anion-change chromatography coupled with ICP-MS was used to speciate these complexes using a mobile phase containing 30 mM NH₄H₂PO₄ at pH of 8.0. However, [Pb(NTA)]¹⁻ was not observed during chromatographic separation due to its poor stability. The species [Pb(HEDTA)]¹⁻, [Pb(EDTA)]²⁻ and [Pb(DTPA)]³⁻ were separated within 15 min with reasonable resolution and detection limits ranging from 0.05 to 0.2 μg L⁻¹ with simple direct injection of sample. The proposed method was used to speciate aminocarboxylic lead complexes in soil solution.     

Development of a Tellurium Speciation Study Using IC-ICP-MS on Soil Samples Taken from an Area Associated with the Storage,Processing, and Recovery of Electrowaste

The optimization and validation of a methodology for determining and extracting inorganic ionic Te(VI) and Te(IV) forms in easily-leached fractions of soil by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry (IC-ICP-MS) were studied. In this paper, the total concentration of Te, pH, and red-ox potential were determined. Ions were successfully separated in 4 min on a Hamilton PRPX100 column with 0.002 mg/kg and 0.004 mg/kg limits of detection for Te(VI) and Te(IV), respectively. Soil samples were collected from areas subjected to the influence of an electrowaste processing and sorting plant. Sequential chemical extraction of soils showed that tellurium was bound mainly with sulphides, organic matter, and silicates. Optimization of soil extraction allowed 20% average extraction efficiency to be obtained, using 100 mM citric acid as the extractant. In the tested soil samples, both tellurium species were present. In most cases, the soils contained a reduced Te form, or the concentrations of both species were similar.     

Simultaneous determination of arsenic and selenium species in fish tissues using microwave-assisted enzymatic extraction and ion chromatography-inductively coupled plasma mass spectrometry

A microwave-assisted enzymatic extraction (MAEE) method was developed for the simultaneous extraction of arsenic (As) and selenium (Se) species in fish tissues. The extraction efficiency of total As and Se and the stability of As and Se species were evaluated by analyzing DOLT-3 (dogfish liver). Enzymatic extraction using pronase E/lipase mixture assisted by microwave energy was found to give satisfactory extraction recoveries for As and Se without promoting interspecies conversion. The optimum extraction conditions were found to be 0.2 g of sample, 20 mg pronase E and 5 mg lipase in 10 mL of 50 mM phosphate buffer, pH 7.25 at 37 °C. The total extraction time was 30 min. The speciation analysis was performed by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS). The accuracy of the developed extraction procedure was verified by analyzing two reference materials, DOLT-3 and BCR-627. The extraction recoveries in those reference materials ranged between 82 and 94% for As and 57 and 97% for Se. The accuracy of arsenic species measurement was tested by the analysis of BCR 627. The proposed method was applied to determine As and Se species in fish tissues purchased from a local fish market. Arsenobetaine (AsB) and selenomethionine (SeMet) were the major species detected in fish tissues. In the analyzed fish extracts, the sum of As species detected was in good agreement with the total As extracted. However, for Se, the sum of its species was lower than the total Se extracted, revealing the presence of Se-containing peptides or proteins.     

Speciation of glyphosate, phosphate and aminomethylphosphonic acid in soil extracts by ion chromatography with inductively coupled plasma mass spectrometry with an octopole reaction system

Ion-pairing chromatography coupled with inductively coupled plasma mass spectrometry (ICP-MS) used for the speciation of phosphorus is limited as the mobile phase containing organic solvents changes in detection sensitivity and the carbon precipitates on torch and cones. To address this issue, anion-exchange chromatography with ICP-MS has been used for the speciation of glyphosate, phosphate and aminomethylphosphonic acid in soil extracts. The separation of the targets on a new column was achieved within 5 min using an eluent containing 20 mM NH₄NO₃ at pH 5.1. Furthermore, since the polyatomic ions such as ¹⁴N¹⁶O¹H⁺ and ¹⁵N¹⁶O⁺ from a nitrogen-based ion-pairing reagent interfered with ICP-MS detection of ³¹P, an octopole reaction system was investigated to determine whether the polyatomic interferences could be reduced. The results show that addition of He to the cell can benefit analyses by reducing such interferences, but at the expense of reduced sensitivity. The detection limits in the range of 1.0-1.5 μg L⁻¹ (expressed as P) was achieved when 50 μL was injected using He as the collusion gas.     

On-line coupling of ion chromatography and atomic spectrometry and use of direct graphite furnace atomic absorption spectrometry as new tools for ultra trace determinations in refractory metals

On-line coupling of inductively coupled plasma (ICP) techniques such as ICP-AES and ICP-MS with ion chromatography (IC) offers unique features for ultra-trace analysis. An on-line preconcentration procedure based on cation exchange enables sub-ng/g analysis in complex matrices like molybdenum and tungsten. The best dissolution reagent for these matrices is hydrogen peroxide, which can be cleaned to ultra high purity with the same metal free chromatography equipment used for the preconcentration. Preconcentration is possible for elements that show cationic reactions within acidic peroxide containing solutions. In this study 28 elements detrimental for microelectronics applications are observed. A comparison of the combinations IC-ICP-AES and IC-ICP-MS with glow discharge mass spectrometry (GDMS) for the analysis of today's purest tungsten samples shows the analytical power and accuracy of the coupled devices. Graphite furnace atomic absorption spectrometry (GFAAS) as an extremely sensitive analytical technique is applied with and without the same sample pretreatment as used for the on-line coupling. Direct GFAAS measurements of alkali metals are complementary to IC-ICP techniques. The data evaluated with these wet chemical techniques are compared to the usual manufacturers characterisation technique GDMS. With respect to the low concentrations present in these high purity materials (ng/g level in the solid) the discrepancies between all methods are acceptable. The sensitivity of IC-ICP-MS is in most cases far superior to IC-ICP-AES and for some elements also to GDMS. Furthermore the specific advantages of on-line coupling such as the elimination of isobaric interferences in ICP-MS or spectral interferences in ICP-AES are shown for ICP-AES and ICP-MS determinations.