Patricia Smichowski

Antimony in the environment as a global pollutant: a review on analytical methodologies for its determination in atmospheric aerosols.

This review summarizes and discusses the research carried out on the determination of antimony and its predominant chemical species in atmospheric aerosols. Environmental matrices such as airborne particulate matter, fly ash and volcanic ash present a number of complex analytical challenges as very sensitive analytical techniques and highly selective separation methodologies for speciation studies. Given the diversity of instrumental approaches and methodologies employed for the determination of antimony and its species in environmental matrices, the objective of this review is to briefly discuss the most relevant findings reported in the last years for this remarkable element and to identify the future needs and trends. The survey includes 92 references and covers principally the literature published over the last decade.

Separation and determination of antimony(III) and antimony(V) species by high-performance liquid chromatography with hydride generation atomic absorption spectrometric and inductively coupled plasma mass spectrometric detection

Methods are described for the effective separation and determination of inorganic antimony species by high-performance liquid chromatography (HPLC)–hydride generation (HG) atomic absorption spectrometry (AAS), HPLC–inductively coupled plasma (ICP) mass spectrometry (MS) and HPLC–HG–ICP-MS. SbIII and SbV were separated on a strong anion-exchange column using phthalic acid as the mobile phase. The optimum conditions for the separation of the antimony species by HPLC and the hydride generation conditions for the determination by AAS were established. Then, the HPLC system was connected to an ICP-MS system using either nebulization or hydride generation sample introduction to improve the detection limits. The detection limits were 5 and 0.6 ng per 100 µl sample for SbIII and SbV, respectively (HPLC–HGAAS). For the HPLC–ICP-MS determination these limits were 0.75 and 0.09 ng and 0.04 and 0.008 ng for the HPLC–HG-ICP-MS coupling. The proposed methods for the simultaneous separation of inorganic antimony species were applied to the determination of SbIII and SbV in spiked and natural water samples. Agreement within the statistical uncertainty was obtained in all instances.

Monitoring trace metals in urban aerosols from Buenos Aires city. Determination by plasma-based techniques

A study was undertaken, within the framework of a 3 years national project, to assess the content of 13 elements in airborne particulate matter collected in representative zones of the metropolitan area of Buenos Aires. The sampling strategy followed consisted in collecting simultaneously 67 samples of PM10 particulate matter in 9 sampling sites covering an area of about 30 km2 during one week. The collection was performed on ash-free fibre-glass filters using high volume samplers. A combination of aqua regia and perchloric acid was used for leaching metals from filters. Key elements, namely Al, Ca, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Sn, Zn and Zr, were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) at micro g g(-1) and ng g(-1) levels. Analyte concentration varied from 130 ng g(-1)(Mo) to over 30%(Ca). Multivariate statistical analysis was performed on the data set including the measured elemental compositions for the monitored period. The atmospheric concentration found for Pb confirms the decreasing levels of this element since the introduction of unleaded gasoline in 1995: 88 ng m(-3)(2001) < 220 ng m(-3)(1997) < 3900 ng m(-3)(1994). The average S concentration above 3 microg m(-3) is somehow unexpectedly high for Buenos Aires since the relatively low S content of liquid fuels and the massive usage of natural gas imply low emissions of this element from combustion activities. To the best of our knowledge, S concentrations are reported for the first time for this city.

Traffic‐Related Elements in Airborne Particulate Matter

Abstract This review covers the investigations done over the last few years to quantify key traffic‐related elements, namely, Pb, Pd, Pt, Rh, and Sb in atmospheric aerosols. From this standpoint, the role played by analytical techniques as diverse as electrothermal atomization atomic absorption spectrometry (ET‐AAS), total reflection X‐ray fluorescence (TXRF) spectrometry, and inductively coupled plasma‐mass spectrometry (ICP‐MS) is also surveyed as a substantial amount of research is presently being performed to further improve the instrumental approach. In their turn, neutron activation analysis (NAA) and particle‐induced X-ray emission (PIXE) are nuclear techniques that were and are employed in this context. The application of ICP‐MS for fractionation studies based on the separation of particles according to their aerodynamic diameter and the use of chemical extraction for metal partitioning in airborne particulate matter and their speciation analysis are also discussed. This survey contains 91 references and covers primarily the literature published over the last decade.

Solid phase extraction of co ions using L-tyrosine immobilized on multiwall carbon nanotubes.

A study was performed to assess the performance of aminoacids immobilized on carbon nanotubes (CNTs) for their employment as a sorbent for solid phase extraction systems. An immobilization method is introduced and the aminoacid L-tyrosine was chosen as a case study. A spectrophotometric study revealed the amount of aminoacid immobilizated on CNTs surface, and it turned to be of 3174 micromol of L-tyrg(-1). The material was tested for Co retention using a minicolumn inserted in a flow system. At pH 7.0, the amount of Co retained by the column was of 37.58+/-3.06 micromol Co g(-1) of CNTs. A 10% (v/v) HNO(3) solution was chosen as eluent. The pH study revealed that Co binding increased at elevated pH values. The calculation of the mol ratio (moles of Co bound at pH 9 to moles of l-tyr) turned to be 3:1. The retention capacity was compared to other bivalent cations and showed the following tendency: Cu(2+)>Ni(2+)>Zn(2+)>>Co(2+). The analytical performance was evaluated and an enrichment factor of 180 was obtained when 10 mL of 11.37 microg L(-1)Co solution was loaded onto the column at pH 9.0; reaching a limit of detection (LoD) of 50 ng L(-1). The proposed system was successfully applied to Co determination in QC-LL2 standard reference material (metals in natural water).

Application of multi-walled carbon nanotubes as substrate for the on-line preconcentration, speciation and determination of vanadium by ETAAS

This paper presents the development of a pre-concentration and speciation method for inorganic vanadium species by flow injection solid phase extraction-electrothermal atomic absorption spectrometry (FI-SPE-ETAAS). This was carried out by employing a conical mini-column filled with multi-walled carbon nanotubes mounted in the arm of the autosampler of the ETAAS. This system was applied to the on-line pre-concentration and speciation of vanadium in natural waters in conjunction with ETAAS determination. The time required for the pre-concentration of 1.0 ml of sample (1.0 ml min−1), elution/injection (0.2 ml min−1), reading/data acquiring and conditioning was about 2.9 min, resulting in a sample throughput of 20 samples per hour. A 20-fold total enrichment factor for a sample volume of 1.0 ml was obtained with respect to the vanadium determination by ETAAS without pre-concentration. The relative standard deviation for six replicates containing 200 ng l−1 was 3.3%. A limit of detection (3s) of 19 ng l−1 was achieved and the limit of quantification was estimated (10s), obtaining a characteristic concentration of 63 ng l−1. The calibration curve was linear from the quantification limit up to 1500 ng l−1, with a correlation coefficient of 0.9996. This method permitted us to determine the total inorganic vanadium in natural waters. For speciation purposes, V(IV) was masked with 1,2 cyclohexanediaminetetraacetic acid (CDTA) in order to determine the V(V) concentration selectively.

Biosorption: A new rise for elemental solid phase extraction methods

Biosorption is a term that usually describes the removal of heavy metals from an aqueous solution through their passive binding to a biomass. Bacteria, yeast, algae and fungi are microorganisms that have been immobilized and employed as sorbents in biosorption processes. The binding characteristics of microorganisms are attributed to functional groups on the surface providing some features to the biosorption process like selectivity, specificity and easy release. These characteristics turn the biosorption into an ideal process to be introduced in solid phase extraction systems for analytical approaches. This review encompasses the research carried out since 2000, focused on the employment of biosorption processes as an analytical tool to improve instrumental analysis. Since aminoacids and peptides as synthetic analogues of natural metallothioneins, proteins present in the cell wall of microorganisms, have been also immobilized on solid supports (controlled pore glass, carbon nanotubes, silica gel polyurethane foam, etc.) and introduced into solid phase extraction systems; a survey attending this issue will be developed as well in this review.

L-tyrosine immobilized on multiwalled carbon nanotubes: a new substrate for thallium separation and speciation using stabilized temperature platform furnace-electrothermal atomic absorption spectrometry.

An approach for the separation and determination of inorganic thallium species is described. A new sorbent, L-tyrosine-carbon nanotubes (L-tyr-CNTs), was used and applied to the analysis of tap water samples. At pH 5.0, L-tyr was selective only towards Tl(III), while total thallium was determined directly by stabilized temperature platform furnace-electrothermal atomic absorption spectrometry (STPF-ETAAS). The Tl(III) specie, which was retained by L-tyrosine, was quantitatively eluted from the column with 10% of nitric acid. An on-line breakthrough curve was used to determine the column capacity, which resulted to be 9.00 micromol of Tl(III) g(-1) of L-tyr-CNTs with a molar ratio of 0.14 (moles of Tl bound to moles of L-tyr at pH 5). Transient peak areas revealed that Tl stripping from the column occurred instantaneously. Effects of sample flow rate, concentration and flow rate of the eluent, and interfering ions on the recovery of the analyte were systematically investigated. The detection limit for the determination of total thallium (3sigma) by STPF-ETAAS was 150 ng L(-1). The detection limit (3sigma) for Tl(III) employing the separation system was 3 ng L(-1), with an enrichment factor of 40. The precision of the method expressed as the relative standard deviation (RSD) resulted to be 3.4%. The proposed method was applied to the speciation and determination of inorganic thallium in tap water samples. The found concentrations were in the range of 0.88-0.91 microg L(-1) of Tl(III), and 3.69-3.91 microg L(-1) of total thallium.

On-line redox speciation analysis of antimony using l-proline immobilized on controlled pore glass and hydride generation inductively coupled plasma optical emission spectrometry for detection.

L-proline was immobilized on controlled pore glass to study the ability of this material for the separation and preconcentration of Sb(III) and Sb(V). The substrate was packed in a minicolumn and incorporated in a flow injection system. The effluents of the on-line solid phase extraction (before and after elution) were directly coupled to the hydride generation inductively coupled plasma optical emission spectrometry system. The effect of pH, sample (and eluent) volume, flow rates of sample loading and elution on separation of Sb(III) e Sb(V) were evaluated. Our experiments demonstrated that Sb(V) was not retained and it was selectively determined during the loading step, while retained Sb(III) was determined after elution. The proposed system was also used for the selective preconcentration of Sb(III). In this case, a preconcentration factor of 11 and a limit of detection of 90 ng L(-1) for Sb(III) were achieved when 8 mL of sample were loaded into the column. The speciation analysis of inorganic Sb in river water and effluent samples was performed using the proposed method. The values obtained for total Sb (obtained by sum of Sb(III) and Sb(V)) were in good agreement with expected values. Recoveries of Sb(III) and Sb(V) in the river water Standard Reference Material 1640 (from National Institute of Standard and Technology) and spiked river waters were between 83 and 111%.

Investigation of arsenic speciation in algae of the Antarctic region by HPLC-ICP-MS and HPLC-ESI-Ion Trap MS

An investigation into presence and nature of As species in algae originating from the Antarctic region is presented in this work. Arsenic speciation information in Antarctic algae samples was obtained by using anion- and cation-exchange chromatography with on-line detection by inductively coupled plasma spectrometry (ICP-MS) or electrospray ionization ion trap mass spectrometry (ESI-ITMS). Total arsenic concentrations found by ICP-MS in the Antarctic algae samples ranged from 8.4 to 29.3 μg As g−1 (dry weight). Arsenic species were efficiently extracted (83–108%) by using an MeOH : H2O (1 : 1) mixture. Anion-exchange chromatography utilizing gradient elution with 25 mM ammonium bicarbonate adjusted to pH 10 was used to separate the anionic As species present in the algae extracts. Additionally, gradient cation-exchange chromatography was performed using 4 mM pyridine solution adjusted to pH 2.4. This allowed the separation of neutral and cationic As species present in the algae extracts. High volatility of the mobile phases allowed sample introduction compatibility with both ICP-MS and ESI-ITMS detectors. Three arsenosugar species (arsenosugar–OH, –SO3, and –PO4) previously reported in marine algae samples accounted for ∼50–80% of the total extractable arsenic in 4 of the 5 samples studied. In one algae sample, the presence of a previously unreported arsenic-containing compound in algae samples was confirmed by ESI-ITMS isolation and fragmentation as 5-dimethylarsinoyl-β-ribofuranose. This compound has been identified previously in marine bivalves but, to our knowledge, not in algae samples.