Janez Ščančar

Jožef Stefan Institute, Lubliano, Ljubljana, Slovenia

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Publications (35)92.04 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Cisplatin is still widely used for treatment of numerous types of tumours. Different speciation methods have been applied to study behaviour of the intact drug and its individual biotransformation species in various clinical samples. These methods are mainly based on electrophoresis, size exclusion (SEC) or ion chromatography (IC) techniques coupled to inductively coupled plasma mass spectrometry (ICP-MS). Hydrophilic interaction liquid chromatography (HILIC), which is a common technique for separation of polar substances, was rarely applied for separation of cisplatin and its hydrolysed metabolites. There is also a lack of information available on the occurrence of cisplatin and its hydrolysed complexes in the environmental waters. In the present study the concentrations of Pt were determined in hospital wastewaters by ICP-MS. A procedure for separation of cisplatin and its aqueous hydrolysed complexes by the use of HILIC column was optimized. Quantification of separated Pt species was performed by isotope dilution (ID)-ICP-MS procedure. Low limits of detection (LODs) and quantification (LOQs) were obtained for cisplatin and its hydrolysed complexes ranging from 0.0273 to 0.1726ngPt/mL and from 0.0909 to 0.5753ngPt/mL, respectively. Good repeatability of the procedure with relative standard deviation (RSD) lower than ±2.3% was obtained. The column recoveries, which ranged from 95 to 101%, indicated that the procedure developed enabled quantitative speciation analysis of aqueous cisplatin complexes. The ZIC-HILIC-ID-ICP-MS procedure was successfully applied in speciation of cisplatin in spiked hospital wastewater samples. Copyright © 2015 Elsevier B.V. All rights reserved.
    Talanta 06/2015; 138. DOI:10.1016/j.talanta.2015.02.008 · 3.51 Impact Factor
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    ABSTRACT: In the present work compact and ground cement composites in which 30% of cement by mass was replaced by ladle slag were investigated for their chemical and physico-mechanical properties. To evaluate long-term environmental impacts, leachability test based on diffusion, which combined both, diffusion and dissolution of contaminants, was performed in water and saline water. Total element concentrations and Cr(VI) were determined in leachates over a time period of 180days. At the end of the experiment, the mineralogical composition and the physico-mechanical stability of cement composites was also assessed. The results revealed that Cr(III) and Cr(VI) were immobilized by the hydration products formed in the cement composites with the addition of ladle slag. Cr(VI) content originating from the cement was also appreciably reduced by Fe(II) from minerals present in the added ladle slag, which thus had significant positive environmental effects. Among metals, only Mo and Ba were leached in elevated concentrations, but solely in ground cement composites with the addition of ladle slag. Lower V concentrations were observed in leachates of ground than compact composite. It was demonstrated that the presence of ladle slag in cement composites can even contribute to improved mortar resistance. The investigated ladle slag can be successfully implemented in cement composites as supplementary cementitious material. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Waste Management 05/2015; DOI:10.1016/j.wasman.2015.05.006 · 3.16 Impact Factor
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    ABSTRACT: Total concentrations of selected trace elements in Neem powder and in Neem tea were determined by inductively coupled plasma mass spectrometry (ICP-MS). The data revealed that despite high total concentrations of the potentially toxic elements Al and Ni in Neem powder, their amounts dissolved in Neem tea were low. Total concentrations of the other toxic elements Pb, As and Cd were also very low and do not represent a health hazard. In contrast, total concentrations of the essential elements Fe, Cu, Zn, Se Mo and Cr in Neem powder were high and also considerable in Neem tea. Consuming one cup of Neem tea (2g per 200mL of water) covers the recommended daily intakes for Cr and Se and represents an important source of Mo and Cu. Speciation analysis of Cr by high performance liquid chromatography (HPLC) coupled to ICP-MS with the use of enriched Cr isotopic tracers to follow species interconversions during the analytical procedure demonstrated that toxic Cr(VI) was not present either in Neem powder or in Neem tea. Its concentrations were below the limits of detection of the HPLC-ICP-MS procedure applied. The speciation analysis data confirmed that even Cr(VI) was added, it was rapidly reduced by the presence of antioxidants in Neem leaves. By the use of enriched Cr isotopic spike solutions it was also demonstrated that for obtaining reliable analytical data it is essential to apply the extraction procedures which prevent Cr species interconversions, or to correct for species transformation. Copyright © 2015 Elsevier GmbH. All rights reserved.
    Journal of Trace Elements in Medicine and Biology 04/2015; 31. DOI:10.1016/j.jtemb.2015.04.003 · 2.49 Impact Factor
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    ABSTRACT: A novel analytical procedure was developed for the simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate by anion-exchange high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Linear gradient elution from 100% water to 100% 0.7M NaCl was applied for chromatographic separation of metal species. In standard aqueous solution at neutral pH molybdate, tungstate and vanadate exist in several aqueous species, while chromate is present as a single CrO4(2-) species. Consequently, only chromate can be separated from this solution in a sharp chromatographic peak. For obtaining sharp chromatographic peaks for molybdate, tungstate and vanadate, the pH of aqueous standard solutions was raised to 12. At highly alkaline conditions single CrO4(2-), MoO4(2-) and WO4(2-) are present and were eluted in sharp chromatographic peaks, while VO4(3-) species, which predominates at pH 12 was eluted in slightly broaden peak. In a mixture of aqueous standard solutions (pH 12) chromate, molybdate, tungstate and vanadate were eluted at retention times from 380 to 420s, 320 to 370s, 300 to 350s and 240 to 360s, respectively. Eluted species were simultaneously detected on-line by ICP-MS recording m/z 52, 95, 182 and 51. The developed procedure was successfully applied to the analysis of leachable concentrations of chromate, molybdate, tungstate and vanadate in alkaline extracts (2% NaOH+3% Na2CO3) of manual metal arc (MMA) welding fumes loaded on filters. Good repeatability and reproducibility of measurement (RSD±3.0%) for the investigated species were obtained in both aqueous standard solutions (pH 12) and in alkaline extracts of welding fumes. Low limits of detection (LODs) were found for chromate (0.02ngCrmL(-1)), molybdate (0.1ngMomL(-1)), tungstate (0.1ngWmL(-1)) and vanadate (0.2ngVmL(-1)). The accuracy of analytical procedure for the determination of chromate was checked by analysis of CRM 545, Cr(VI) in welding dust loaded on a filter. Good agreement between determined and reported certified values was obtained. For molybdate, tungstate and vanadate the assessment of accuracy was performed by spiking welding fume filters. Good recoveries for all investigated species (98-101%) confirmed the accuracy of the analytical procedure. Copyright © 2015 Elsevier B.V. All rights reserved.
    Talanta 04/2015; 142. DOI:10.1016/j.talanta.2015.04.067 · 3.51 Impact Factor
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    ABSTRACT: An important step in pharmacological characterisation of a candidate drug is the study of the drugs interactions with serum proteins. In the present work, conjoint liquid chromatography (CLC) was used for separation of ruthenium (Ru)-based drug candidates in human serum. CIM Protein G and CIM DEAE disks were assembled together in a single housing forming a CLC monolithic column. By applying isocratic elution with Tris–HCl–NaHCO3 buffer (pH 7.4) in the first min, followed by gradient elution with 1 mol L−1 NH4Cl (pH 7.4) in the next 9 min, immunoglobulins (IgG) were retained by the Protein G disk enabling subsequent separation of unbound Ru species from Ru species bound to human serum transferrin (Tf) and albumin (HSA) on the CIM DEAE disk. Finally, elution with acetic acid (AcOH) in the next 3 min allowed separation of Ru species associated with IgG. Protein elution was followed on-line with UV detection at 278 nm, while the separated Ru species were quantified by post-column isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). The instrumental set-up enabled fast two-dimensional separation by affinity and ion-exchange modes to be carried out in a single chromatographic run. Two Ru-based chemotherapeutics: a newly synthesised compound chlorido(η6-p-cymene)(nalidixicato-κ2O,O)Ru(II) (1) and (H2im)[trans-Ru(III)Cl4(Him)2] (2; KP418), which is currently undergoing preclinical studies, were investigated. The CLC procedure applied is sensitive with low limit of detection (LOD) (0.027 μg Ru mL−1 for (1)) and good method repeatability (RSD ± 3.5%). The experimental data revealed that it enables investigation of the kinetics of interaction of positively charged and neutral complexes of metallodrugs with serum proteins as well as the distribution of metallodrug species in human serum. However, negatively charged metallic complexes co-eluted with Tf and HSA and thus hindered their speciation analysis. An example of successful application of the kinetic studies on the CLC column is (1), a neutral Ru complex that hydrolyses to a positively charged species. For comparison, speciation data obtained for serum samples spiked with cisplatin are also shown.
    Journal of Chromatography A 10/2014; 1371. DOI:10.1016/j.chroma.2014.10.054 · 4.26 Impact Factor
  • Janez Ščančar, Radmila Milačič
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    ABSTRACT: The role and impact of chromium (Cr) on the environment and living organisms depends primarily on its chemical form. High toxicity of hexavalent Cr is well documented, while trivalent Cr is an essential micronutrient. In the last decades numerous analytical procedures have been developed for the determination of Cr(VI) in different sample matrices. To obtain reliable speciation data it is important to preserve species integrity during the sample storage, pre-treatment, extraction and the determination of Cr species. Among different speciation methods combination of high performance liquid chromatography (HPLC) with atomic spectrometry techniques provides comprehensive information on the presence of Cr species in a variety of sample matrices, while hyphenation of HPLC to inductively coupled plasma mass spectrometry (ICP-MS) represents the most powerful and the most sensitive analytical tool for Cr speciation. Precise isotope ratio measurement enables the application of isotope dilution techniques for the quantification of trace amounts of individual Cr species in various environmental and biological samples. Furthermore, enriched stable isotopes can be introduced as tracers to investigations on the fate and role of Cr in the environment and living organisms or to monitor the species transformation during the analytical procedure. Despite general understanding of Cr chemistry, which is closely related to its trivalent and hexavalent oxidation states and knowledge on conditions that may influence species transformation, there are still open questions that should be addressed to obtain reliable speciation analysis data. So, this article is focused mostly to overview recent developments in methodological approaches for Cr speciation in different sample matrices by applying HPLC and spectrometric techniques. Different procedures for preparation of isotopically enriched Cr spike solutions are critically evaluated. The advantages of their use as tracers to follow and account for species transformation during sample preparation and for the quantification of Cr species by HPLC-ID-ICP-MS are discussed. The importance of the use of adequate analytical methodologies and speciation analysis in the determination of Cr(VI) is highlighted in order to avoid inadequate conclusions to be made based on wrongly applied analytical methodologies. An increasing need to develop speciation procedures for selective determination of Cr(III) species is also emphasized.
    Journal of Analytical Atomic Spectrometry 03/2014; 29(3):427. DOI:10.1039/c3ja50198a · 3.40 Impact Factor
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    ABSTRACT: Conjoint liquid chromatography (CLC) on monolithic convective interaction media (CIM) disks coupled on-line to UV and inductively coupled plasma mass spectrometry (ICP-MS) detectors was used for the first time in speciation analysis of Pt in human serum spiked with Pt-based chemotherapeutics. CIM Protein G and CIM DEAE disks were assembled together in a single housing forming a CLC monolithic column. Such a set-up allows rapid two-dimensional separation by affinity and ion-exchange (IE) modes to be carried out in a single chromatographic run. By applying isocratic elution with Tris–HCl–NaHCO3 buffer (pH 7.4) in the first minute, followed by gradient elution with 1 mol L−1 NH4Cl (pH 7.4) in the next 9 min, immunoglobulins (IgG) were retained by the Protein G disk enabling subsequent separation of unbound Pt from Pt bound to transferrin (Tf) and albumin (HSA) on the CIM DEAE disk. Further elution with acetic acid (AcOH) in the next 3 min allowed separation of Pt associated with IgG. Separated Pt species were quantified by post-column isotope dilution—ICP-MS. Pt recovery on the CLC column was close to 100%. In comparison to commonly applied procedures that involve separation of protein peaks by size-exclusion chromatography (SEC) followed by IE separation of metal-based chemotherapeutic fractions bound to serum proteins, the CLC method developed is much faster and simpler. Its sensitivity (LOQs adequate for quantification of all separated Pt species, lower than 2.4 ng Pt mL−1), good selectivity and method repeatability (RSD±3%) enabled investigation of the kinetics of interaction of Pt-based chemotherapeutics with serum proteins and the distribution of Pt species in spiked human serum. Pt species present in spiked serum were bound preferentially to HSA. The proportion of Pt associated with IgG and Tf was lower than 13%. Cisplatin and especially oxaliplatin react rapidly with serum proteins, while carboplatin much less. The method developed may be reliably applied in preclinical and clinical studies of the kinetics of the interaction and distribution of different metallodrugs with proteins in blood serum.
    Talanta 11/2013; 116:141–148. DOI:10.1016/j.talanta.2013.05.016 · 3.51 Impact Factor
  • Janez Ščančar, Tea Zuliani, Radmila Milačič
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    ABSTRACT: In the present study, total nickel (Ni) concentration was determined in selected food products in Slovenia by inductively coupled plasma mass spectrometry (ICP-MS) after microwave assisted digestion of samples. The accuracy of the analytical procedure was checked by the determination of nickel in SRM 2976 NIST Mussel tissue and SRM 1548a NIST Typical diet standard reference materials. Results confirmed that soya products (yoghurt and tofu), cacao and cacao products (dark and milk chocolates) and hazel nuts are important sources of dietary Ni. The content of Ni in different teas infusions was too low to significantly contribute to Ni daily intake. Cooking of acidic foodstuffs in stainless steel kitchenware leached Ni in concentrations similar to those in teas. Micro-ultrafiltration (MWCO 3000 Da) of cacao cooked in water or milk revealed that Ni in these drinks is present in the form of low molecular mass (LMM) species and that milk proteins are not able to compete for Ni in the presence of LMM-Ni binding ligands.
    Journal of Food Composition and Analysis 11/2013; 32(1):83–89. DOI:10.1016/j.jfca.2013.06.011 · 2.26 Impact Factor
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    ABSTRACT: Recently several papers were published in highly ranked journals on the presence of Cr(VI) in tea infusions, bread samples and plants. These statements were made on the basis of determination of total Cr concentrations in alkaline and aqueous sample extracts by ETAAS, without applying any speciation analysis. If Cr(VI) really exists in bread samples and tea infusions, consumption of bread and tea would represent long-term chronic exposure to Cr(VI) and a health threat for the majority of the human population. It is well accepted that due to the presence of organic matter foodstuffs of plant and animal origin cannot contain Cr(VI). Therefore, to show that the reported data on the presence of Cr(VI) in foodstuffs are an artefact of inappropriately applied analytical methodology, investigation of speciation was carried out by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). 50Cr(VI) and 53Cr(III) stable isotopes were used to follow species interconversions during the extraction procedures. Separated Cr species eluted from the column were followed at m/z 50, 52 and 53. The high sensitivity of the HPLC-ICP-MS method (LOD for m/z 52, 0.03 μg Cr(VI) L−1) enabled reliable determination of Cr(VI) at concentration levels that were much lower than the total Cr content present in sample extracts. The speciation analysis data demonstrated that in all samples analysed Cr(VI) concentrations were below the LOD. In tea infusions 50Cr(VI) was almost completely reduced due to the presence of antioxidants, while the high content of organic matter in bread appreciably reduced 50Cr(VI) even in highly alkaline (pH 12) bread extracts. The data confirmed that Cr(VI) does not exist in foodstuffs of plant origin and provided some conclusive evidence that the same can be expected for foods of animal origin.
    Journal of Analytical Atomic Spectrometry 02/2013; 28(4). DOI:10.1039/C3JA30233D · 3.40 Impact Factor
  • J. Ščančar, T. Zuliani, D. Žigon, R. Milačič
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    ABSTRACT: Cited By (since 1996):3, Export Date: 18 October 2014
    Analytical and Bioanalytical Chemistry 01/2013; 405(6):2041-2051. · 3.58 Impact Factor
  • Radmila Milačič, Tea Zuliani, Janez Ščančar
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    ABSTRACT: Aluminum (Al) is mostly produced from bauxite ore, which contains up to 70% of Al(2)O(3) (alumina). Before alumina is refined to aluminum metal, it is purified by hot alkaline extraction. As a waste by-product red mud is formed. Due to its high alkalinity and large quantities, it represents a severe disposal problem. In Kidričevo (Slovenia), red mud was washed with water before disposal, and after drying, covered with soil. In Ajka (Hungary), the red mud slurry was collected directly in a containment structure, which burst caused a major accident in October 2010. In the present work the environmental impact of toxic elements in red mud from Kidričevo and Ajka were evaluated by applying a sequential extraction procedure and speciation analysis. The predominant red mud fraction was the insoluble residue; nevertheless, environmental concern was focused on the highly mobile water-soluble fraction of Al and Cr. Al in the water-soluble Ajka mud fraction was present exclusively in form of toxic [Al(OH)(4)](-), while Cr existed in its toxic hexavalent form. Comparative assessment to red mud from Kidričevo (Slovenia) with a lower alkalinity (pH 9) with that from Ajka demonstrated significantly lower Al solubility and the presence of only trace amounts of Cr(VI), confirming that disposal of neutralized mud is environmentally much more acceptable and carries a smaller risk of ecological accidents. Since during the Ajka accident huge amounts of biologically available Al and moderate Cr(VI) concentrations were released into the terrestrial and aquatic environments, monitoring of Al and Cr(VI) set free during remedial actions at the contaminated site is essential. Particular care should be taken to minimize the risk of release of soluble Al species and Cr(VI) into water supplies and surface waters.
    Science of The Total Environment 04/2012; 426:359-65. DOI:10.1016/j.scitotenv.2012.03.080 · 4.10 Impact Factor
  • Tea Zuliani, Radmila Milačič, Janez Ščančar
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    ABSTRACT: The characterisation of a laboratory quality control material (QCM) for dibutyltin (DBT) and tributyltin (TBT) in sewage sludge is described. The reference values were determined by the use of two different types of isotope-dilution mass spectrometry: gas chromatography-mass spectrometry and gas chromatography-inductively coupled plasma mass spectrometry. To avoid possible analytical errors such as non-quantitative extraction and species degradation during sample preparation, different extraction methods were tested (microwave- and ultrasound-assisted extraction and mechanical stirring). The reference values were based on the unweighted means of results from the homogenisation and characterisation studies. The reference values obtained were 1,553 ± 87 and 534 ± 38 ng Sn g(-1) for DBT and TBT, respectively. In the uncertainty budget estimation, the sample inhomogeneity and between-method imprecision were taken into account. The concentrations of DBT and TBT in QCM are similar to those in the harbour sediment certified reference material PACS-2. Likewise, the levels of DBT and TBT are in the range of these compounds normally present in sewage sludge worldwide. In the future, the QCM will be used for an intercomparison study on DBT and TBT in sewage sludge, and as a day-to-day QCM during studies concerning the application of sewage sludge as an additive to artificial soil or as a raw material in civil engineering construction.
    Analytical and Bioanalytical Chemistry 03/2012; 403(3):857-65. DOI:10.1007/s00216-012-5897-7 · 3.58 Impact Factor
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    ABSTRACT: Determination of Cr(VI) in aqueous samples including carbonate matrix solutions was performed by fast proteinliquid chromatography (FPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). NaCl was used for separation of Cr species representing a high burden of total dissolved solids for plasma. In addition, detection ofCr species in the NaCl and carbonate matrix was severely compromised also by chlorine and carbon polyatomic interferences at m/z 52 and 53. The influence of high amounts of chloride and carbonate ions on detection ofCr species was investigated using ICP-MS with a High Matrix Introduction (HMI) system, which reduced the sample aerosol transport and enabled direct analysis of separated Cr species in the presence of up to 4% NaCl. The potential of Helium Collision mode (He mode) and High Energy Collision Mode (HECM) to reduce polyatomic interferences from chlorine and carbon on m/z 52 and 53 was also evaluated. It was experimentally proven that for efficient removal of chlorine and carbon polyatomic interferences HECM instead of commonly used He mode should be applied. By applying HMI and HECM, determination of Cr(VI) in carbonatebuffer matrices using NaCl as eluent is possible, following the most abundant Cr 52 and 53 isotopes. Despite the use of HMI and HECM, which significantly reduce the analytetransport to plasma and detector, low LODs were obtained for Cr(VI): 0.01 ng mL−1 at m/z 50, 0.06 ng mL−1 at m/z 52 and 0.02 ng mL−1 at m/z 53. The repeatability of the measurement (5 ng Cr(VI) mL−1) was better than ±1.5%. The simple solution of efficient lowering of the blank at low pH arising from a stainless steel injection needle was also demonstrated by the use of the reverse injection of samples.
    Journal of Analytical Atomic Spectrometry 02/2012; 27(3):488-495. DOI:10.1039/C2JA10270F · 3.40 Impact Factor
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    ABSTRACT: In this work, data on the level of organotin compounds (OTCs) in seawater and mussels collected along the entire Croatian Adriatic Coast are presented. The samples were collected in 2009 and 2010 at 48 locations representing different levels of maritime activities, including marinas, ports and reference sites. Butyltins (BuTs) were found in all analyzed samples, representing >97% of OTCs, and ranged from 0.46 to 27.98 ng Sn L(-1) in seawater and from <6 to 1675 ng Sn g(-1) in mussels. The results indicate a recent input of TBT, with the highest concentrations of BuTs found in the marinas. It appears that the Adriatic coast is still polluted with TBT despite the fact that TBT-containing antifouling paints have been banned in Croatia since 2008. It is questionable how much TBT pollution decreased since 2005, when a high incidence of imposex was established in the same area.
    Marine Pollution Bulletin 02/2012; 64(2):189-99. DOI:10.1016/j.marpolbul.2011.12.009 · 2.79 Impact Factor
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    Andreja Ramšak, Janez Ščančar, Milena Horvat
  • Simona Murko, Janez Ščančar, Radmila Milačič
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    ABSTRACT: To understand the pathways of Altransport in human body it is necessary to identify and quantify Al species present in human serum. It has been demonstrated that about 90% of Al in human serum corresponds to high molecular mass species (HMM-Al) and that Al is bound exclusively to transferrin (Tf). The remaining Al exists in low molecular mass species (LMM-Al) bound predominantly to Al-citrate. In studies of the efficiencies of the chelation therapies and to perform kinetic studies of Al binding to Tf, rapid and reliable analytical procedures are required. Therefore, a new analytical procedure for the efficient, reliable and fast separation of proteins from LMM compounds in serum was developed by the use of a HiTrap desalting size exclusion column. Unspiked and spiked human serum that was left for six hours to reach approximately thermodynamic equilibrium were studied. The separation of HMM-Al from LMM-Al species was accomplished with tris-HCl buffer (pH 7.4) in 10 min. Al elution profile was followed by ICP-MS detection. In the first 5 min HMM-Al compounds were eluted, followed by the elution of LMM-Al species from 5 to 10 min. Results demonstrated that about 94% of Al was present in the HMM (protein) fraction. To prove the reliability of the fractionation procedure developed, the protein peak and LMM separated species were collected in 5 mL fractions, followed by the previously developed speciation procedures. Speciation of the protein peak by CIM® DEAE-ICP-MS verified that about 98% of Al was bound to Tf. In the LMM serum fraction Al-citrate was separated on the FPLC column coupled to ICP-MS. Speciation data confirmed the reliability of the developed fast fractionation procedure. It represents a promising tool for investigations of kinetics of Al binding to Tf and may also be applied in studies of the efficiencies of the chelation therapies in patients overloaded with Al.
    Journal of Analytical Atomic Spectrometry 12/2010; 26(1):86-93. DOI:10.1039/C0JA00088D · 3.40 Impact Factor
  • L. Pograjc, V. Stibilj, J. Ščančar, M. Jamnik
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    ABSTRACT: The energy and nutrient values for military nutrition are defined in the nutritional recommendations of the Slovene Armed Forces. In this study 35 daily military diets sampled in the years 2002 and 2005 by the double basket method were analysed, for energy, total fat, protein, dietary fibre and the elements Ca, Mg, Na, P, K, Fe, Zn, Cu, I and Se. The daily diets were collected at different locations in Slovenia. The aim was to establish whether energy value, content of fat, protein, dietary fibre and selected essential elements are in compliance with the nutritional recommendations of the Slovene Armed Forces. The results indicate that daily intake of essential elements from military meals was sufficient, with the exception of Ca and Zn in diets sampled in 2005. The study was the first in Slovenia analysing daily intakes of essential elements in an adult population aged 19–27 years.
    Food Chemistry 10/2010; 122(4):1235-1240. DOI:10.1016/j.foodchem.2010.03.031 · 3.26 Impact Factor
  • Janez Ščančar, Radmila Milačič
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    ABSTRACT: Monolithic supports are increasingly used in the field of chromatography. They are appropriate for different applications (e.g., separation of biomolecules, organic acids and inorganic anions). However, only a few research groups are investigating the potential of using monolithic phases for rapid separation of metal cations and elemental speciation analysis.Monolithic supports based on porous monolithic silica have been successfully applied in separation of alkaline-earth and transition-metal cations in environmental waters and high ionic-strength samples.The present review covers applications of monolithic supports for chromatographic separation of metal cations and the potential for using monolithic chromatography in elemental speciation analysis. We critically evaluate the performances and the advantages of monolithic supports and compare them to conventional particle-packed chromatographic supports.
    TrAC Trends in Analytical Chemistry 10/2009; 28(9-28):1048-1056. DOI:10.1016/j.trac.2009.06.005 · 6.61 Impact Factor
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    ABSTRACT: A continuous 60-year record (1938–1998) of stable isotope compositions of carbon and oxygen, as well as trace metal (Mg, Sr, Ba) concentrations in a laminated calcite crust precipitated in a short artificial tunnel on a non-equilibrium groundwater-fed karstic river is presented. Chemical and isotopic records have been compared to hydrometeorological data, available for the last 48 years. An attempt is made to relate isotopic and geochemical variations in the crust to environmental parameters, such as temperature, precipitation and changes in vegetation cover, as well as to postdepositional recrystallisation of the older crust material. Isotopic composition of the crust is largely influenced by non-equilibrium precipitation, which favours the incorporation of isotopically depleted C and O into the carbonate. Furthermore, because of the complicated hydrological situation, there is no observable correlation between the stable oxygen isotope composition of water and temperature. The result is that the 18 O isotopic thermometers overestimate the measured precipitation temperatures. Temperatures calculated from Mg/Ca ratios of water and the carbonate match the δ 18 O palaeotemperatures within ±2.4 °C in the older part of the crust, precipitated before the onset of industrial pollution of the river. It was demonstrated that the application of Mg palaeothermometry in natural systems, where the Mg/Ca ratio of water is influenced not only by temperature, but also by other environmental parameters such as precipitation, surface runoff, groundwater retention time and anthropogenic influences, is subject to a large uncertainty, up to 10 °C.
    Chemical Geology 01/2009; 258:242-250. DOI:10.1016/j.chemgeo.2008.10.013 · 3.48 Impact Factor
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    ABSTRACT: The extent of pollution with organotin compounds was investigated in water, sediment and bivalve mussels (Mytilus galloprovincialis) from the Northern Adriatic Sea. Butyl-, phenyl- and octyltin species were quantified after extraction and derivatisation by gas chromatography–mass spectrometry in a total of 99 samples from the period from 2000 to 2006. The accuracies of the analytical procedures were checked by spiking of unpolluted water samples and by the analysis of standard reference materials (harbour sediment PACS-2 and mussel tissue ERM-CE 477). Among organotin species analysed in samples butyltins were the predominant. Tributyltin was found to be present in the highest concentrations, suggesting its recent input into the marine environment. Butyltins were detected at all sites surveyed (sum of butyltins was up to 718ng Sn L−1, 3,552ng Sn g−1 d.w. and 9,991ng Sn g−1 d.w. in water, sediment and mussel samples, respectively), phenytins in much lower concentrations (up to 31ng Sn L−1, 326ng Sn g−1 d.w. and 442ng Sn g−1 d.w. in water, sediment and mussel samples) and to a much smaller extent, while octyltins were not detected at any location. The spatial distribution of tributyltin was closely related to boating, with the highest concentrations found in marinas (up to 586ng Sn L−1 for water samples, 1,995ng Sn g−1 d.w. for sediment and 6,434ng Sn g−1 d.w. for mussel samples). The temporal distribution clearly indicates a decrease of organotin pollution at all sites.
    Water Air and Soil Pollution 12/2008; 196(1):211-224. DOI:10.1007/s11270-008-9770-4 · 1.69 Impact Factor