Extraction and pre-concentration of platinum and palladium from microwave-digested road dust via ion exchanging mesoporous silica microparticles prior to their quantification by quadrupole ICP-MS

We report on the use of mesoporous silica microparticles (mu Ps) functionalized with quarternary amino groups for the isolation of platinum and palladium tetrachloro complexes from aqueous road dust digests. The mu Ps have a size ranging from 450 to 850 nm and are suspended directly in the aqueous digests, upon which the anionic Pt and Pd complexes are retained on the cationic surface. Subsequently, the mu Ps are separated by centrifugation. Elements that cause spectral interferences in ICP-MS determination of Pt and Pd can be quantitatively removed by adding fresh 0.240 mol L-1 HCl to the mu Ps and by repeating the centrifugation step. The analyte-loaded mu Ps are then dissolved in 0.1 mL of 2 mol L-1 HF, diluted to 2 mL, and the solutions thus obtained are analyzed by quadrupole ICP-MS. This method avoids analyte elution from the sorbent. This "dispersed particle extraction" approach yielded a run-to-run relative standard deviation a parts per thousand currency signaEuro parts per thousand 5 % for Pt and a parts per thousand currency signaEuro parts per thousand 4 % for Pd (at 0.1 ng mL(-1), n = 4 road dust digests). Method detection limits (expressed as concentrations in the dust samples) are 2 and 1 ng g(-1) for Pt and Pd, respectively. The method was validated by analysis of a reference material (BCR CRM 723) and applied to the analysis of road dust samples collected in downtown Vienna. Pt and Pd concentrations in samples collected in summer and in winter were compared, with concentrations ranging from 205 to 1445 ng g(-1) for Pt and from 201 to 1230 ng g(-1) for Pd

Radial line-scans as representative sampling strategy in dried-droplet laser ablation of liquid samples deposited on pre-cut filter paper disks

Nebulising liquid samples and using the aerosol thus obtained for further analysis is the standard method in many current analytical techniques, also with inductively coupled plasma (ICP)-based devices. With such a set-up, quantification via external calibration is usually straightforward for samples with aqueous or close-to-aqueous matrix composition. However, there is a variety of more complex samples. Such samples can be found in medical, biological, technological and industrial contexts and can range from body fluids, like blood or urine, to fuel additives or fermentation broths. Specialized nebulizer systems or careful digestion and dilution are required to tackle such demanding sample matrices. One alternative approach is to convert the liquid into a dried solid and to use laser ablation for sample introduction. Up to now, this approach required the application of internal standards or matrix-adjusted calibration due to matrix effects. In this contribution, we show a way to circumvent these matrix effects while using simple external calibration for quantification. The principle of representative sampling that we propose uses radial line-scans across the dried residue. This compensates for centro-symmetric inhomogeneities typically observed in dried spots. The effectiveness of the proposed sampling strategy is exemplified via the determination of phosphorus in biochemical fermentation media. However, the universal viability of the presented measurement protocol is postulated. Detection limits using laser ablation-ICP-optical emission spectrometry were in the order of 40 mu g mL(-1) with a reproducibility of 10 % relative standard deviation (n = 4, concentration = 10 times the quantification limit). The reported sensitivity is fit-for-purpose in the biochemical context described here, but could be improved using ICP-mass spectrometry, if future analytical tasks would require it. Trueness of the proposed method was investigated by cross-validation with conventional liquid measurements, and by analyzing IAEA-153 reference material (Trace Elements in Milk Powder); a good agreement with the certified value for phosphorus was obtaine

Metal(loid) bioaccessibility and inhalation risk assessment: A comparison between an urban and an industrial area

The content of metal(loid)s in particulate matter (PM) is of special concern due to their contribution to overall (PM) toxicity. In this study, the bioaccessibility and human health risk of potentially toxic metal(loid)s associated with PM10 were investigated in two areas of the Cantabrian region (northern Spain) with different levels of exposure: an industrial area mainly influenced by a ferromanganese alloy plant; and an urban area consisting mainly of residential and commercial activities, but also affected, albeit to a lesser extent by the ferroalloy plant. Total content and bioaccessible fractions in simulated lung fluids (SLFs) of Fe, Mn, Zn, Ni, Cu, Sb, Mo, Cd and Pb were determined by ICP-MS. Gamble's solution and artificial lysosomal fluid (ALF) were used to mimic different conditions inside the human respiratory system. A health risk assessment was performed based on the United States Environmental Protection Agency's (USEPA) methodology. Most metal(loid)s showed moderate and high bioaccessibility in Gamble's solution and ALF, respectively. Despite the high variability between the samples, metal(loid) bioaccessibility was found to be higher on average at the industrial site, suggesting a greater hazard to human health in the proximity of the main metal(loid) sources. Based on the results of the risk assessment, the non-carcinogenic risk associated with Mn exposure was above the safe limit (HQ> 1) under all the studied scenarios at the industrial site and under some specific scenarios at the urban location. The estimated carcinogenic inhalation risk for Cd exposure at the industrial site was found to be within the range between 1.0 × 10−6 to 1.0 × 10−4 (uncertainty range) under some scenarios. The results obtained in this study indicate that Mn and Cd inhalation exposure occurring in the vicinities of the studied areas may pose a human health risk.This work was financially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through the CTM2013–43904R Project. Ana Hernández-Pellón would like to thank the Ministry of Economy and Competitiveness (MINECO) for the FPI and research stay grants awarded, reference numbers BES-2014-068790 and EEBB-I-17-12031

Recent advances in quantitative LA-ICP-MS analysis : challenges and solutions in the life sciences and environmental chemistry

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is a widely accepted method for direct sampling of solid materials for trace elemental analysis. The number of reported applications is high and the application range is broad; besides geochemistry, LA-ICP-MS is mostly used in environmental chemistry and the life sciences. This review focuses on the application of LA-ICP-MS for quantification of trace elements in environmental, biological, and medical samples. The fundamental problems of LA-ICP-MS, such as sample-dependent ablation behavior and elemental fractionation, can be even more pronounced in environmental and life science applications as a result of the large variety of sample types and conditions. Besides variations in composition, the range of available sample states is highly diverse, including powders (e.g., soil samples, fly ash), hard tissues (e.g., bones, teeth), soft tissues (e.g., plants, tissue thin-cuts), or liquid samples (e.g., whole blood). Within this article, quantification approaches that have been proposed in the past are critically discussed and compared regarding the results obtained in the applications described. Although a large variety of sample types is discussed within this article, the quantification approaches used are similar for many analytical questions and have only been adapted to the specific questions. Nevertheless, none of them has proven to be a universally applicable method

New strategies for quantifying trace elements in challenging liquid samples by means of inductively coupled plasma-mass spectrometry and -optical emission spectrometry

Zusammenfassung in deutscher SpracheIm Rahmen dieser Dissertation wurden neue Methoden entwickelt, die die Messung von Spurenelementen in herausfordernden flüssigen Proben wie beispielsweise Vollblut oder Fermentationsmedien mittels induktiv gekoppeltem Plasma mit optischer Emissionsspektrometrie (ICP-OES) und Massenspektrometrie (ICP-MS) erlauben. Herausfordernde flüssige Proben können zu den folgenden Problemen bei herkömmlicher ICP-OES oder ICP-MS Messung führen: 1. Unspezifische Matrix-Effekte können auftreten, wenn flüssige Proben beispielsweise hohe Konzentrationen an gelösten organischen oder anorganischen Bestandteilen enthalten, oder wenn sie sich deutlich von gewöhnlichem Wasser hinsichtlich Dichte, Viskosität, Oberflächenspannung, oder Säuregehalt unterscheiden. 2. Die Proben können Bestandteile enthalten, die zu spektralen Interferenzen führen. Das ist insbesondere von großer Bedeutung in der Spurenanalytik mittels ICP-MS. 3. Die Konzentrationen der Analyten können zu niedrig für eine vernünftige Quantifizierung sein. Als alternative Probeneintrags-Methode wurde daher die Methode der -dried droplet Laser Ablation- optimiert und angewendet. Dabei wird ein Tropfen der flüssigen Probe eingetrocknet und mittels Laser Ablation ins ICP gebracht. Dabei werden die oben erwähnten unspezifischen Matrix-Effekte deutlich verringert. -Dispersed particle extraction- wurde entwickelt, um Analyten aus flüssigen Proben selektiv zu extrahieren und anzureichern. Diese Methode beruht auf herkömmlicher Festphasenextraktion, vermeidet aber einige Nachteile dieser etablierten Methode (beispielsweise das Eluieren der Analyten, Memory-Effekte, Alterung des Sorbensmaterials). Mit -dispersed particle extraction- lassen sich Probenbestandteile entfernen, die zu spektralen Interferenzen führen können. Schlussendlich wurden beide Methoden (dried droplet Laser Ablation und dispersed particle extraction) kombiniert, um zusätzliche Vorteile wie bessere Sensitivität und höhere Toleranz gegenüber gelösten Feststoffen während der Messung auszunutzen.Inductively coupled plasmas (ICPs) are widely and routinely used in the quantification of element concentrations in liquid samples and solutions. The combination of ICP with optical emission spectrometry (ICP-OES) is the older and more rugged technique, however, its sensitivity is often not sufficient in case of (ultra-)trace element quantification. Compared to ICP-OES, ICP-mass spectrometry (ICP-MS) offers superior sensitivity, but is inherently more prone to matrix effects. Although ICP-OES and ICP-MS are well-established in routine-laboratories, the accuracy of analysis using a conventional instrumental set-up can be hampered due to the following reasons: matrix effects due to sample properties, and insufficient selectivity and/or sensitivity. In the doctoral thesis new strategies are presented which were developed to tackle those challenges.11

Development of advanced methods for the determination of Platinum Group Elements in plant material

Zsfassung in dt. SprachePlatin, Palladium und Rhodium zählen zu den Platin- Gruppen Elementen (PGE). Diese Metalle werden in großen Mengen als Katalysatoren in der chemischen Industrie und in Kraftfahrzeugen eingesetzt. Aufgrund von Verschleiß werden PGE aus Autokatalysatoren freigesetzt und lagern sich in unmittelbarer Umgebung von Verkehrsflächen ab. Über die Toxizität und/oder die krebserzeugende Wirkung dieser Metalle ist noch wenig bekannt. Solange die tatsächliche Auswirkung der PGE auf Lebewesen noch nicht vollständig geklärt ist, sollte diesen Elementen vermehrte Aufmerksamkeit zukommen.Die Analyse von PGE in Umweltproben gestaltet sich oft schwierig, da die natürliche Hintergrundkonzentration dieser Elemente sehr niedrig ist.Desweiteren kommt erschwerend hinzu, dass die meisten analytischen Methoden durch Komponenten, die in Umweltproben allgegenwärtig sind, stark negativ beeinflusst werden Das Entfernen dieser störenden Komponenten oder das Korrigieren ihrer negativen Einflüsse stellt die größte Herausforderung in der Analytik dieser Spurenmetalle dar.In dieser Diplomarbeit werden zwei Methoden präsentiert, die eine Analyse von PGE in Umweltproben ermöglichen: im ersten Teil (chapter 2) wird eine neue Art der Probenvorbereitung mittels einer modifizierten Festphasenextraktion präsentiert, die eine Anreicherung von Palladium aus wässrigen Lösungen ermöglicht, wodurch eine Verteilungsanalyse dieses Metalls in unterschiedlichen Pflanzenorganen möglich wurde. Im zweiten Teil (chapter 3) wird eine Methode zur direkten Feststoffanalyse von Pflanzenmaterial mittels ETV ICP-OES beschrieben.Der große Vorteil dieser Methode besteht darin, dass kein Aufschließen der Proben notwendig ist, wodurch einerseits der Einsatz von bedenklichen Chemikalien vermieden werden kann und andererseits eine verbesserte Nachweisstärke erzielt wird.Platinum, Palladium and Rhodium are members of the Platinum group Elements (short PGEs); these elements are used as catalysts in the chemical industry as well as in automobile catalysts. Due to abrasion, PGEs are co-emitted with the vehicle's exhaust gases and are deposited along roadsides. Knowledge about PGE's toxicity and/or carcinogenic behaviour is still scarce and monitoring of these elements is required.The analysis of PGEs in environmental samples is a rather challenging task because the natural background-concentration of these elements is very low. Furthermore, many analytical methods are interfered by compounds inherent to environmental surroundings which are found to be several orders of magnitude higher in concentration than the PGEs. It is obvious that the removal of these interferences respectively the correction of their negative effects is considered a major task in trace metal analysis.In this Diploma Thesis two methods for the assessment of PGEs in plant material are presented: in the first part (chapter 2) a novel approach in sample pre-treatment using a modified solid phase extraction method is introduced which allows the enrichment of palladium from aqueous solutions. The spatial distribution of this analyte in various parts of the plants was determined.Direct sampling of PGE containing plant material using electro thermal vaporisation ICP-OES is presented in the second part (chapter 3). The major advantage of this direct sampling approach lies in the reduction of time consuming sample pre-treatment steps and the avoidance of potentially dangerous chemicals that are usually required for digestion.7

Multi-element analysis of size-segregated fine and ultrafine particulate via Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

In this study a novel and reliable Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICPMS) measurement protocol for the elemental characterization of size-segregated particulate was developed. Special efforts were made to improve and optimize sample pre-treatment steps and LA operating conditions to avoid some critical drawbacks encountered during analysis and to make the particulate samples suitable for an accurate and reproducible LA-ICP-MS analysis, regardless of the mass loading on each filter. For example, a new approach for dust-fixation on the sample-carrier was developed using a glycerol coverage, which allowed to overcome problematic sample losses during the ablation process. Under the optimum conditions, dust samples, blank filters and standards for calibration were analyzed by multiple rastering of defined spot areas. Quantitative analysis was accomplished with dried micro-droplets of aqueous standard solutions. Derived method detection limits varied between 0.001 and 0.1 ngm3 and allowed even for the smallest particle fraction quantitative measurements. The accuracy of LA-ICP-MS results was verified by comparison with conventional ICP-MS analysis of selected PM samples after sample mineralization. The proposed LA treatment procedure benefits from a simple and fast sample preparation, thus overcoming the laborious pre-treatment steps required for wet chemical digestion. Moreover, the better sensitivity of the LA-ICP-MS approach provided more complete information about the mass concentration and size-distribution of the investigated elements, thus allowing to deeper investigate the composition of the most dangerous PM fractions in terms of health concern

Combining dispersed particle extraction with dried-droplet laser ablation ICP-MS for determining platinum in airborne particulate matter

A combination of analyte pre-concentration using dispersed particle extraction (DPE) and dried-droplet laser ablation inductively coupled mass spectrometry (LA-ICP-MS) was developed with the aim to quantify Pt and Pd in urban particulate matter with an aerodynamic diameter <= 2.5 mu m (PM2.5). The PM2.5 aerosol was collected on cellulose ester filters during a sampling period of three days, with sampling intervals of 4 h only. Each of the filters was chemically digested, and the resulting solution was pre-concentrated using DPE. Droplets taken from the pre-concentrated sample were deposited on polymeric disks and dried. These dry spots were then analyzed by means of LA-ICP-MS. This approach allowed ICP-MS analysis of solutions with high content of dissolved sorbent particles coming from the DPE procedure. Furthermore, spectral interferences arising from sample-inherent matrix elements as well as solvent-related interferences could be removed by the proposed approach. The method was validated by determining the Pt concentration in Bureau Communautaire de Reference certified reference material (BCR CRM) 723 road dust certified reference material and a good agreement with the certified value was obtained. The temporal variation of Pt during the three-day sampling period is discussed, with respect to automotive traffic. The daily average of Pt measured in the air corresponds to typical values observed in urban areas in Central Europe. Although the pre-concentration of palladium is feasible with dispersed particle extraction, the method detection limits achieved here did not allow to quantify this element in the CRM or in the PM2.5 samples. The source for these high method detection limits for palladium are blank values arising from the filter material as well as the digestion procedure of the PM2.5 samples. Instrumental sensitivity of the approach would, however, suggest that palladium quantification is possible, provided the abovementioned blank issues are controlled better