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Baxter, Douglas
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Publications (10 of 58) Show all publications
Rodushkin, I., Pallavicini, N., Engström, E., Sörlin, D., Öhlander, B., Ingri, J. & Baxter, D. C. (2016). Assessment of the natural variability of B, Cd, Cu, Fe, Pb, Sr, Tl and Zn concentrations and isotopic compositions in leaves, needles and mushrooms using single sample digestion and two-column matrix separation (ed.). Paper presented at . Journal of Analytical Atomic Spectrometry, 31(1), 220-233
Open this publication in new window or tab >>Assessment of the natural variability of B, Cd, Cu, Fe, Pb, Sr, Tl and Zn concentrations and isotopic compositions in leaves, needles and mushrooms using single sample digestion and two-column matrix separation
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2016 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 31, no 1, p. 220-233Article in journal (Refereed) Published
Abstract [en]

An analytical procedure allowing multi-elemental analyses and isotope ratio measurements of eight of these (B, Cd, Cu, Fe, Pb, Sr, Tl and Zn) in matrices relevant for bio-monitoring using a single highpressure acid digestion was developed. Method blanks, separation efficiency of matrix elements, repeatability and reproducibility were evaluated using sets of preparation blanks, certified reference materials and duplicate samples prepared and analyzed over a period of several months. The method was used to assess the natural variability of concentrations and isotopic compositions in bio-indicators (tree leaves, needles and mushrooms, over 240 samples) collected mainly from a confined area in North-East Sweden. Ranges found from leaves and needles were compared with data obtained for limited numbers of samples collected in Spain, Italy, France, United Kingdom and Iceland.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-14151 (URN)10.1039/C5JA00274E (DOI)000367315200018 ()2-s2.0-84952898602 (Scopus ID)d7cbb017-e0af-48ac-b1b7-ca535fa94cc0 (Local ID)d7cbb017-e0af-48ac-b1b7-ca535fa94cc0 (Archive number)d7cbb017-e0af-48ac-b1b7-ca535fa94cc0 (OAI)
Note
Validerad; 2016; Nivå 2; 20151201 (nicpal)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Pallavicini, N., Engström, E., Baxter, D. C., Öhlander, B., Ingri, J. & Rodushkin, I. (2014). Cadmium isotope ratio measurements in environmental matrices by MC-ICP-MS (ed.). Paper presented at . Journal of Analytical Atomic Spectrometry, 29(9), 1570-1584
Open this publication in new window or tab >>Cadmium isotope ratio measurements in environmental matrices by MC-ICP-MS
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2014 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 29, no 9, p. 1570-1584Article in journal (Refereed) Published
Abstract [en]

Various stages of an analytical method for high-precision cadmium (Cd) isotope ratio measurements by MC-ICP-MS (sample preparation, matrix separation, instrumental analysis and data evaluation) were critically evaluated and optimized for the processing of carbon-rich environmental samples. Overall reproducibility of the method was assessed by replicate preparation and Cd isotope ratio measurements in various environmental matrices (soil, sediment, Fe-Mn nodules, sludge, kidney, liver, leaves) and was found to be better than 0.1‰ (2σ for δ114Cd/110Cd) for the majority of samples. Cd isotope ratio data for several commercially-available reference materials are presented and compared with previously published results where available. The method was used in a pilot study focusing on the assessment of factors affecting Cd isotope composition in tree leaves. A summary of results obtained for a large number (n > 80) of birch (Betula pubescenes) leaves collected from different locations in Sweden and through the entire growing season is presented and potential reasons for observed variability in Cd isotope composition are discussed. Seasonal dynamics of element concentrations and isotope compositions in leaves were also compared for Os, Pb, Zn and Cd.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-8521 (URN)10.1039/c4ja00125g (DOI)000341064300003 ()2-s2.0-84905757655 (Scopus ID)7084b45f-c467-4588-94c9-40f1a9a13212 (Local ID)7084b45f-c467-4588-94c9-40f1a9a13212 (Archive number)7084b45f-c467-4588-94c9-40f1a9a13212 (OAI)
Note
Validerad; 2014; 20140821 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Pallavicini, N., Ecke, F., Engström, E., Baxter, D. & Rodushkin, I. (2013). A high-throughput method for the determination of Os concentrations and isotope ratio measurements in small-size biological samples (ed.). Paper presented at . Journal of Analytical Atomic Spectrometry, 28(10), 1591-1599
Open this publication in new window or tab >>A high-throughput method for the determination of Os concentrations and isotope ratio measurements in small-size biological samples
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2013 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 28, no 10, p. 1591-1599Article in journal (Refereed) Published
Abstract [en]

An analytical method allowing multi-element characterization by external calibration, osmium (Os) concentration determination by isotope dilution (ID) and 187Os/188Os isotope abundance ratio measurement from a single sample preparation was developed. The method consists of microwave-assisted, closed-vessel acid digestion of small (0.01-0.4 g dry weight) biological samples spiked with Os solution enriched in a 190Os isotope followed by concentration and Os isotope ratio measurements using double-focusing, sector field inductively coupled plasma mass-spectrometry (ICP-SFMS) operated with methane addition to the plasma and solution nebulization (SN) sample introduction. For samples with Os content below 500 pg, complementary analysis using gas-phase introduction (GPI) on the remaining sample digests was performed. The use of disposable plastic lab ware for sample digestion and analysis by SN ICP-SFMS circumvents Os carry-over effects and improves the sample throughput and cost-efficiency of the method. For a 0.1 g dried sample, Os method limits of detection (MLODs) of 2 pg g -1 and 0.2 pg g-1 were obtained using SN or GPI, respectively. Long-term reproducibility of 187Os/188Os isotope abundance ratio measurements using the GPI approach was better than 1.5% RSD for our in-house control sample (moose kidney) with an Os concentration of approximately 5 pg g-1. Os data for several commercially available reference materials of biological or plant origin (not certified for Os) are presented. The method was used in the large scale bio-monitoring of free-living bank voles from an area affected by anthropogenic Os emissions.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-9547 (URN)10.1039/c3ja50201e (DOI)000324414800003 ()2-s2.0-84883871721 (Scopus ID)831b6e4f-3f9d-4a4c-b345-62813987fd40 (Local ID)831b6e4f-3f9d-4a4c-b345-62813987fd40 (Archive number)831b6e4f-3f9d-4a4c-b345-62813987fd40 (OAI)
Note
Validerad; 2013; 20130924 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Österlund, H., Faarinen, M., Ingri, J. & Baxter, D. (2012). Contribution of organic arsenic species to total arsenic measurements using ferrihydrite-backed diffusive gradients in thin films (DGT) (ed.). Paper presented at . Environmental Chemistry, 9(1), 55-62
Open this publication in new window or tab >>Contribution of organic arsenic species to total arsenic measurements using ferrihydrite-backed diffusive gradients in thin films (DGT)
2012 (English)In: Environmental Chemistry, ISSN 1448-2517, E-ISSN 1449-8979, Vol. 9, no 1, p. 55-62Article in journal (Refereed) Published
Abstract [en]

In previous publications discussing arsenic determination using ferrihydrite-backed diffusive gradients in thin films (DGT) devices, organic arsenic forms have been disregarded, even though it is known that the two most prevalent in natural waters, dimethylarsinate (DMA) and monomethylarsonate (MMA), may adsorb to ferrihydrite and thereby be included in the measurement. In this work the accumulation of DMA and MMA, as well as inorganic arsenite and arsenate, to ferrihydrite-backed DGT devices was investigated. It could be demonstrated that MMA, and under acidic conditions also DMA, adsorbed to the binding layer and might therefore contribute to the total mass of measured arsenic. Diffusion coefficients were measured for all four species to enable quantification of DGT-labile concentrations of organic and inorganic arsenic. Elution of the analytes from the ferrihydrite binding layer was performed using 1 mL of 1 M NaOH to facilitate arsenic speciation analysis using chromatographic separation. Average recovery rates were between 87 and 108%. This study shows that the contribution of DMA and MMA to the total accumulated mass must be taken into consideration when evaluating DGT data in future studies.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-5613 (URN)10.1071/EN11057 (DOI)000300656800002 ()2-s2.0-84857513440 (Scopus ID)3c2cc5af-dd36-45d3-8273-e60c6c110c77 (Local ID)3c2cc5af-dd36-45d3-8273-e60c6c110c77 (Archive number)3c2cc5af-dd36-45d3-8273-e60c6c110c77 (OAI)
Note
Validerad; 2012; 20120305 (helost)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Österlund, H., Gelting, J., Nordblad, F., Baxter, D. & Ingri, J. (2012). Copper and nickel in ultrafiltered brackish water: labile or non-labile? (ed.). Paper presented at . Marine Chemistry, 132-133(1), 34-43
Open this publication in new window or tab >>Copper and nickel in ultrafiltered brackish water: labile or non-labile?
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2012 (English)In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 132-133, no 1, p. 34-43Article in journal (Refereed) Published
Abstract [en]

Copper and nickel were sampled at three stations in the Baltic Sea using diffusive gradients in thin films (DGT) passive samplers and ultrafiltration (< 1 kDa). Two versions of DGT devices were used, the normal open pore (OP) and a restricted pore (RP). The OP DGT and RP DGT concentrations closely followed each other both in depth profiles and time series. The lack of significant difference between OP and RP DGT suggests that the labile complexes were smaller than the pore size of the RP gel (approximately 1 nm). These data, together with OP DGT measurements at the same location in two different years, clearly demonstrate that the DGT method is robust and indicates reproducible results during routine field conditions.Between 50 and 80% of the ultrafiltered fractions for Ni and Cu could not be detected by the DGT method, using standard procedures. This suggests the presence of complexing ligands for Cu and Ni. Assuming 100% complexation of Ni to fulvic acid ligand gave DGT concentrations similar to ultrafiltered Ni concentrations. The equivalent calculation for Cu indicates that up to 75% of the ultrafiltered Cu fraction is non-labile. The non-labile Cu complexes are proposed to be produced at sea since the fraction increases with decreasing terrestrial influence.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-11162 (URN)10.1016/j.marchem.2012.02.002 (DOI)000302929700005 ()2-s2.0-84857987453 (Scopus ID)a1182336-9740-4fbe-9847-32a86145dd86 (Local ID)a1182336-9740-4fbe-9847-32a86145dd86 (Archive number)a1182336-9740-4fbe-9847-32a86145dd86 (OAI)
Note
Validerad; 2012; 20120214 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Baxter, D., Rodushkin, I. & Engström, E. (2012). Isotope abundance ratio measurements by inductively coupled plasma-sector field mass spectrometry (ed.). Paper presented at . Journal of Analytical Atomic Spectrometry, 27(8), 1355-1381
Open this publication in new window or tab >>Isotope abundance ratio measurements by inductively coupled plasma-sector field mass spectrometry
2012 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 27, no 8, p. 1355-1381Article in journal (Refereed) Published
Abstract [en]

This tutorial reviews fundamental aspects of isotope abundance ratio measurement by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). After a synopsis of the scope of isotope abundance ratio measurement and a summary introduction to the factors affecting precision and accuracy, attention is turned to noise sources. Detailed theory behind Poisson or counting statistics and plasma flicker noise components is given, since much of the observed imprecision can be attributed to these sources. Using single collector instruments, ion beams from different isotopes are sampled in rapid sequence, and so ratioing of the signals will be subject to fluctuations derived from intensity variations, i.e., flicker noise. It is demonstrated that flicker noise can, under specified circumstances, become the limiting factor for the attainable precision. Furthermore, the practice of partitioning dwell times, ostensibly to optimize precision based on isotopic abundances and assumed Poisson statistics, is shown to be flawed and actually requires accounting for flicker noise. In addition to random uncertainty, various offset factors may contribute to systematic error in measured isotope abundance ratios. Two of these, namely mass scale shift and spectral interferences are ameliorated using ICP-SFMS. The former is eliminated when operating under conditions providing flat-topped peaks, such that the minor drift in mass calibration typical of the technique becomes inconsequential and the intensity remains the same. Isotope abundance ratio measurements are subject to three further important offset factors. First is abundance sensitivity, which quantifies the extent of peak tailing to neighboring masses and can present a considerable source of offset. Second is mass bias, resulting from the fact that all sector field devices exhibit increasing sensitivity with ion mass, and various empirical methods used to correct for this effect are compared and contrasted. Third is detector dead time, which affects mass spectrometers equipped with ion counting systems. Although a well-understood phenomenon, all current methods for determining the dead time on the basis of experimentally measured isotope abundance ratios are likely to yield biased estimates. Finally, the capabilities of ICP-SFMS for the determination of isotope abundance ratios are placed in perspective by making a brief comparison with other techniques.

National Category
Physical Chemistry
Research subject
Chemistry of Interfaces
Identifiers
urn:nbn:se:ltu:diva-16109 (URN)10.1039/C2JA30153A (DOI)000307306600001 ()fb05b00d-1849-445c-8480-698aef7c787c (Local ID)fb05b00d-1849-445c-8480-698aef7c787c (Archive number)fb05b00d-1849-445c-8480-698aef7c787c (OAI)
Note
Upprättat; 2012; 20120817 (mivu)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Rodushkin, I., Baxter, D. & Engström, F. (2011). Inorganic constituents of nuts and seeds (ed.). In: (Ed.), Victor R. Preedy; Ronald Ross Watson; Vinood B. Patel (Ed.), Nuts and Seeds in Health and Disease Prevention: (pp. 65-72). Paper presented at . : Elsevier
Open this publication in new window or tab >>Inorganic constituents of nuts and seeds
2011 (English)In: Nuts and Seeds in Health and Disease Prevention, Elsevier, 2011, p. 65-72Chapter in book (Refereed)
Abstract [en]

This chapter presents data on the inorganic components of hazelnuts, walnuts, almonds, pecans, cashews, Brazil nuts, pistachios, pine nuts, peanuts, coconuts, pumpkin seeds, and sunflower seeds. Based on average consumption data for nuts and seeds, their nutritional significance and toxicological relevance in dietary intake are discussed.

Place, publisher, year, edition, pages
Elsevier, 2011
National Category
Geochemistry Metallurgy and Metallic Materials
Research subject
Applied Geology; Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-21371 (URN)10.1016/B978-0-12-375688-6.10007-6 (DOI)2-s2.0-84884836308 (Scopus ID)df0bf2bd-0058-4158-ae67-375fefea550b (Local ID)978-0-12-375688-6 (ISBN)df0bf2bd-0058-4158-ae67-375fefea550b (Archive number)df0bf2bd-0058-4158-ae67-375fefea550b (OAI)
Note
Godkänd; 2011; 20131011 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Baxter, D., Faarinen, M., Österlund, H., Rodushkin, I. & Christensen, M. (2011). Serum/plasma methylmercury determination by isotope dilution gas chromatography: inductively coupled plasma mass spectrometry (ed.). Paper presented at . Analytica Chimica Acta, 701(2), 134-138
Open this publication in new window or tab >>Serum/plasma methylmercury determination by isotope dilution gas chromatography: inductively coupled plasma mass spectrometry
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2011 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 701, no 2, p. 134-138Article in journal (Refereed) Published
Abstract [en]

A method for the determination of methylmercury in plasma and serum samples was developed. The method uses isotope dilution with 198Hg-labelled methylmercury, extraction into dichloromethane, back-extraction into water, aqueous-phase ethylation, purge and trap collection, thermal desorption, separation by gas chromatography, and mercury isotope specific detection by inductively coupled plasma mass spectrometry. By spiking 2 mL sample with 1.2 ng tracer, measurements in a concentration interval of (0.007–2.9) μg L−1 could be performed with uncertainty amplification factors <2. A limit of quantification of 0.03 μg L−1 was estimated at 10 times the standard deviation of concentrations measured in preparation blanks. Within- and between-run relative standard deviations were <10% at added concentration levels of 0.14 μg L−1, 0.35 μg L−1 and 2.8 μg L−1, with recoveries in the range 82% to 110%. Application of the method to 50 plasma/serum samples yielded a median (mean; range) concentration of methylmercury of 0.081 (0.091; <0.03–0.19) μg L−1. This is the first time methylmercury has been directly measured in this kind of specimen, and is therefore the first estimate of a reference range.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-9918 (URN)10.1016/j.aca.2011.06.012 (DOI)000294144400003 ()21801879 (PubMedID)2-s2.0-79960742571 (Scopus ID)89f81c28-4778-4575-b596-e7ef287cb1da (Local ID)89f81c28-4778-4575-b596-e7ef287cb1da (Archive number)89f81c28-4778-4575-b596-e7ef287cb1da (OAI)
Note
Validerad; 2011; 20110620 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Österlund, H., Chlot, S., Faarinen, M., Widerlund, A., Rodushkin, I., Ingri, J. & Baxter, D. (2010). Simultaneous measurements of As, Mo, Sb, V and W using a ferrihydrite diffusive gradients in thin films (DGT) device (ed.). Paper presented at . Analytica Chimica Acta, 682(1-2), 59-65
Open this publication in new window or tab >>Simultaneous measurements of As, Mo, Sb, V and W using a ferrihydrite diffusive gradients in thin films (DGT) device
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2010 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 682, no 1-2, p. 59-65Article in journal (Refereed) Published
Abstract [en]

The ferrihydrite-backed DGT (diffusive gradients in thin films), recently developed for arsenic and phosphate measurements was, for the first time, characterized with respect to molybdate, antimonate, vanadate and tungstate determination. Arsenate was included in the characterization to allow comparison with literature data and thus provide quality control of the measurements. In addition to laboratory experiments, field measurements were carried out in a natural stream in northern Sweden affected by mine drainage. It was shown that ferrihydrite-DGT is suitable for simultaneous determination of labile arsenic, molybdate, antimonate, vanadate and tungstate over a wide pH range. Diffusion coefficients were estimated using two different methods; diffusion cell and direct uptake to DGT devices in synthetic solutions. Estimations of the coefficients using the direct uptake method were performed between pH 4 and 8. The results from the two methods agreed well irrespective of pH, except for molybdate and antimonate that showed decreased values at pH 8. Adsorption of the analytes to ferrihydrite gel discs was rapid at all pH values. However, there was a tendency toward lower adsorption affinity for antimonate compared to the other anions. 100% recovery of accumulated analytes was achieved through complete dissolution of the ferrihydrite adsorbent using 1.4 mol L-1 HNO3 with 0.1 mol L-1 HF. From field sampling it was concluded that the opportunities for accurate antimonate and molybdate determination decrease at pH ≥8.7. DGT labile concentrations were generally lower than dissolved concentrations. Relatively lower DGT concentrations, compared to dissolved (<0.45 μm), were observed under a period when ferric oxide precipitations were detected on the DGT protective filter.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-2653 (URN)10.1016/j.aca.2010.09.049 (DOI)000284974300006 ()21056715 (PubMedID)2-s2.0-78149411296 (Scopus ID)04da9fa0-d7a0-11df-8b36-000ea68e967b (Local ID)04da9fa0-d7a0-11df-8b36-000ea68e967b (Archive number)04da9fa0-d7a0-11df-8b36-000ea68e967b (OAI)
Note
Validerad; 2010; 20101014 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Rodushkin, I., Engström, E. & Baxter, D. (2010). Sources of contamination and remedial strategies in the multi-elemental trace analysis laboratory (ed.). Paper presented at . Analusis, 396(1), 365-377
Open this publication in new window or tab >>Sources of contamination and remedial strategies in the multi-elemental trace analysis laboratory
2010 (English)In: Analusis, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 396, no 1, p. 365-377Article in journal (Other academic) Published
Abstract [en]

In theory, state of the art inductively coupled plasma mass spectrometry (ICP-MS) instrumentation has the prerequisite sensitivity to carry out multi-elemental trace analyses at sub-ng L-1 to sub-pg L-1 levels in solution. In practice, constraints mainly imposed by various sources of contamination in the laboratory and the instrument itself, and the need to dilute sample solutions prior to analysis ultimately limit detection capabilities. Here we review these sources of contamination and, wherever possible, propose remedial strategies that we have found efficacious for ameliorating their impact on the results of multi-elemental trace analyses by ICP-MS. We conclude by providing a list of key points to consider when developing methods and preparing the laboratory to routinely meet the demands of multi-elemental analyses at trace analytical levels by ICP-MS.

National Category
Physical Chemistry Geochemistry
Research subject
Chemistry of Interfaces; Applied Geology
Identifiers
urn:nbn:se:ltu:diva-15653 (URN)10.1007/s00216-009-3087-z (DOI)000272564100034 ()19730826 (PubMedID)2-s2.0-72849116654 (Scopus ID)f31260e0-c225-11de-b769-000ea68e967b (Local ID)f31260e0-c225-11de-b769-000ea68e967b (Archive number)f31260e0-c225-11de-b769-000ea68e967b (OAI)
Note
Validerad; 2009; 20091026 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved

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