1. Ana BANICA Prøveforelesning 2006 1 Analytical methods for studying trace metal speciation in the natural environment (Analytiske metoder for speciering av spormetaller i naturen) As Hg Cr Sn Se Pb Cd Fe Cu Zn Ni Co Al ….. Date: 8 February 2006 Duration: 45 minutes Target groups: 1 st and 2 nd year Chemistry students

2. Ana BANICA Prøveforelesning 2006 2

3. 3 Contents 1.Chemical speciation and fractionation 2.Analytical strategies and methodological approaches 3.In-situ (on-field) speciation analysis in aquatic systems 4.Conclusions

4. Ana BANICA Prøveforelesning 2006 4 1. Chemical Speciation and Fractionation

5. Ana BANICA Prøveforelesning 2006 5 Chemical Speciation and Fractionation Chemical species Speciation analysis Speciation of an element Fractionation Acc. to “Guidelines for terms related to chemical speciation and fractionation of elements. Definitions, structural aspects, and methodological approaches” (IUPAC Recommendations, Pure Appl. Chem. 2000) - Specific forms of an element Fe(II)/Fe(III); As(III)/As(V) CuCl 2 /CuCO 3; Hg/CH 3 HgCl - Activity of identifying and measuring species - Distribution amongst chemical species in a system - Analytes classification according to physical or chemical properties

6. Ana BANICA Prøveforelesning 2006 6 Speciation of Metals Isotopic composition Electronic and oxidation state Inorganic compounds and complexes Organometalic compounds Organic and macromolecular complexes

7. Ana BANICA Prøveforelesning 2006 7 Benefits and Fields of Interest

8. Ana BANICA Prøveforelesning 2006 8 What is determining the biogeochemical impact of the metal ions species in aqueous systems? Concentration Nature of considered organism Physico-chemical form: Particulate ( > 1 µm) Colloidal (1 nm – 1 µm) Dissolved (< 1 nm):  Free metal ions  Simple inorganic complexes  Complexes with anthropogenic and natural ligands

9. Ana BANICA Prøveforelesning 2006 9 2. Analytical Strategies and Methodological Approaches

10. Ana BANICA Prøveforelesning 2006 10 Analytical Strategy – the Main Steps 1.Formulation of the problem 2.Sampling and sample preparation 3.Measurement of the analytical signal 4.Analytical signal interpretation (quantitative and qualitative) 5.Critical evaluation of the analytical performances and method validation

11. Ana BANICA Prøveforelesning 2006 11 What is relevant in a metal speciation study? Individual species Groups of different species with similar properties 1.Formulation of the problem

12. Ana BANICA Prøveforelesning 2006 12 Exchangeable fraction: species most available for bio- uptake (reagent used: acetic acid 0.11 M) Reducible fraction: potentially available for plants (reagent used: a reducing agent like hydroxylamine chloride) Oxidizable fraction: potentially available for plants (reagent used: an oxidizing agent like H 2 O 2 and NH 4 COOCH 3 ) Rezidual fraction: contains naturally occurring minerals Bio-uptake of Metal Species in Soils

13. Ana BANICA Prøveforelesning 2006 13 Bio-uptake of Metal Species in Aquatic Systems Free metal ions – related to biological uptake Dynamic metal species (free metal ions and small labile complexes) – potentially availably for organisms The particulate and colloidal species – role in transport and residence time The total extractable metals – the reservoir of metal in the test solution

14. Ana BANICA Prøveforelesning 2006 14 The Baia Mare Accident !! Higher toxicity due to heavy metals (Cu(II), Zn(II)) Surface-water sampling sites

15. Ana BANICA Prøveforelesning 2006 15 Metal Species in Aquatic Systems Free metal ions – related to biological uptake Dynamic metal species (free metal ions and small labile complexes) – potentially availably for organisms The particulate and colloidal species – role in transport and residence time The total extractable metals – the reservoir of metal in the test solution

16. Ana BANICA Prøveforelesning 2006 16 A major challenge in speciation analysis Sampling – Sample preparation Sampling Transport Pre-treatment Preservation Contamination Loss of analyte Species transformation 2. Sampling and Sample Preparation

17. Ana BANICA Prøveforelesning 2006 17 What is influencing the species stability? Chemical factors Physical factors Biological factors

18. Ana BANICA Prøveforelesning 2006 18 Treatments for Sample Preservation Acidification Low-temperature Drying Freezing Pasteurization Lyophilization Adsorption on cartridges or solid-phase micro-columns Storage in the dark Preservation of Sb samples: - Acidification to prevent hydrolysis - Extraction on solid-phase

19. Ana BANICA Prøveforelesning 2006 19 Artifacts in Sample Speciation O2O2 Fe(OH) 3 Precipitation Sorption onto the container walls Fe 2+ Glass cell PS film coated glass Adapted from J. P. Pinheiro et al., Anal. Bioanal. Chem., 2004 Pb 2+ (aq) Pb 2+ (ads) 0.2  M Pb 2+, pH 6

20. Ana BANICA Prøveforelesning 2006 20 Analytical Methods for Trace Metal Analysis and Speciation Analysis 3. Measurement of the analytical signal Measuring techniques Atomic spectroscopy Inductively coupled plasma-mass spectroscopy (ICP-MS) Neutron activation analysis (NAA) X-ray photoelectron spectroscopy Electroanalytical methods Separation/ extraction Chromatography (GC, LC, HPLC) Capillary electrophoresis Ion-chromatography L-L extraction; Ion-exchange; co-precipitation….

21. Ana BANICA Prøveforelesning 2006 21 IC-ICP-MS Chromatogram of 50  g/L Arsenic Species Dimethylarsinic acid (DMA, cacodylic acid) O || H 3 C-As-CH 3 | OH Arsenic acid (As +5 ) O || HO-As-OH | OH Arsenious acid (As +3 ) HO-As-OH | OH Monomethylarsonic acid (MMA) O || H 3 C-As-OH | OH Hyphenated techniques for speciation analysis Separation – Excitation – Detection HPLC – ICP – MS GC – ICP – MS IC – ICP – MS

22. Ana BANICA Prøveforelesning 2006 22 Metals speciation analysis by electroanalytical techniques Sample Free metal ion activity Free metal ion and labile forms concentration Voltammetry Potentiometry

23. Ana BANICA Prøveforelesning 2006 23 Ion-selective electrodes Free metal ion activity, a I LOD: 10 -7 – 10 -6 M 10 -11 – 10 -8 M Bioavailability Speciation Speciation of Pb(II) and Cd(II) in drinking water Detection of free Cu(II) in sea water The uptake of Cd(II) species by plant roots Acc. E. Bakker, E. Pretsch, Trends Anal. Chem., 2005.

24. Ana BANICA Prøveforelesning 2006 24 Trace metal speciation analysis by voltammetry Anodic stripping voltammetry (ASV) Adsorptive stripping voltammetry (AdSV) Potentiometric stripping analysis (PSA) Anodic stripping voltammetry (ASV) Voltammetric cell Potentiostat Current – potential curves i - E WE RE AE Measured signal in SWASV

25. Ana BANICA Prøveforelesning 2006 25 How is an ASV experiment working ? How is an ASV experiment working ? 3 steps experiment: I. Accumulation/Preconcentration (M z+ + ze - M 0 (Hg)) II. Equilibration III. Measurement of the analytical signal (M 0 (Hg)) M z+ + ze - )

26. Ana BANICA Prøveforelesning 2006 26 Strengths and advantages of the voltammetric techniques Accuracy Sensitivity Simplicity Low detection limit (ppm - ppt) Well-suited for automatic in situ speciation Allow to determine the complexing properties of model or naturally occurring complexants

27. Ana BANICA Prøveforelesning 2006 27 5. Critical evaluation of the analytical performances and methods validation  To test accuracy and traceability  Use of CRM (Certified Reference Materials) SupplierNameMaterialCertificate BCRCRM 626SolutionArsenobetaine BCRCRM 544Lyophilized solutionCr(III), Cr(VI) NISTSRM 2108SolutionCr(III) NISTSRM 2109SolutionCr(VI) Example of simple certified reference materials for speciation analysis of arsenium and chromium in water samples

28. Ana BANICA Prøveforelesning 2006 28 Acc. G. W. Luther III et al., Environ. Sci. Technol. 33 (1999) 4352 In situ detection of O 2, Fe(II), Mn(II) in sediments porewaters with unprotected Au/Hg WE (100 μm) Why validation methods are important?

29. Ana BANICA Prøveforelesning 2006 29 3. In-situ (on-field) speciation analysis in aquatic systems

30. Ana BANICA Prøveforelesning 2006 30 ATMA (Automated Trace Metal Analyzer) VIP (Voltammetric In situ Profiler) MPCP (Multi Physical-Chemical Profiler) In-situ voltammetric analyzers

31. Ana BANICA Prøveforelesning 2006 31 ATMA PSA measurements Electrodes: a mercury film deposited on a glassy carbon rod or a thin gold electrode Used for measuring As(III); Cr(VI); Cu(II); Hg(II); Se(IV). Interferences from matrix (organics, solids, other metals) can have a dramatic effect on the accuracy of the instrument Caution in use on unpredictable or unknown effluents Automated Trace Metal Analyzer (ATMA) Acc. to Space and Naval Warfare Systems Center, San Diego, USA (2002)

32. Ana BANICA Prøveforelesning 2006 32 In situ trace metal speciation based on bioanalogical sensors VIP (Voltammetric In situ Profiler) MPCP (Multi Physical-Chemical Profiler) Gel protected voltammetric microelectrodes - GIME - Gel Integrated Microelectrode - CGIME - Complexing Gel Integrated Microelectrode - PLM –  TAS - Permeation Liquid Membrane – Total Analytical System

33. Ana BANICA Prøveforelesning 2006 33 Model of metal uptake by a biological cell Bulk solution Diffusive boundary layer Cell membrane Cell interior Cell wall layer k int, M

34. Ana BANICA Prøveforelesning 2006 34 GIME (gel-integrated micro-sensor) Agarose gel Ir Si 3 N 4 Silicon Test solution (volume) Hg (5 μm)

35. Ana BANICA Prøveforelesning 2006 35 CGIME (complexing gel-integrated micro-sensor) Agarose gel Si 3 N 4 Silicon Ir Test solution (volume) Resin Hg (5 μm)

36. Ana BANICA Prøveforelesning 2006 36 From voltammetric sensors to in situ probes

37. Ana BANICA Prøveforelesning 2006 37 array of interconnected GIMEBased on an array of interconnected GIME sensors covered with a 300  m thick agarose antifouling gel dynamic fractionMeasures the concentration of dynamic fraction of trace metals (Cu(II), Pb(II), Cd(II), Zn(II), Mn(II), Fe(II)) VIP – Voltammetric In situ Profiler www.idronaut.it

38. Ana BANICA Prøveforelesning 2006 38 Voltammetric in situ profiler (VIP)

39. Ana BANICA Prøveforelesning 2006 39 Environmental monitoring and pollution control Biogeochemical studies  Speciation of Cu, Cd, Pb  Pressure  pH  Temperature  O 2  Conductivity  Salinity  Redox potential  Turbidity  Chlorophyll a MPCP (Multi Physical-Chemical Profiler) a system for in-situ trace metal speciation Acc. to M.-L. Tercier-Waeber/ Marine Chemistry 2005 MPCP

40. Ana BANICA Prøveforelesning 2006 40 MPCP – 3 channels configuration Channel 1 GIME Dynamic fraction of trace metals Channel 2 CGIME Free metal ion Channel 3 FIA - GIME Total extractable metal concentration

41. Ana BANICA Prøveforelesning 2006 41 Speciation analysis of copper with MPCP Acc. to M.-L. Tercier-Waeber/ Marine Chemistry 2005

42. Ana BANICA Prøveforelesning 2006 42 Conclusions - In situ voltammetric speciation analysis have many advantages - It demands improvement of the voltammetric devices

43. Ana BANICA Prøveforelesning 2006 43 4. Conclusions

44. Ana BANICA Prøveforelesning 2006 44 Interdisciplinarity and Speciation Analysis Analytical Chemistry Environmental Chemistry Biology and Biochemistry Geochemistr y Transport processes Consumptive processes (chemical reactions and biological uptake)

45. Ana BANICA Prøveforelesning 2006 45 Summary Analysis of trace metals in the natural environment Speciation analysisFractionation Location LaboratoryIn situ

46. Ana BANICA Prøveforelesning 2006 46 Suggestions for further reading R. Cornelis, J. Caruso, H. Crews, K. Heuman (Eds.), Handbook of Elemental Speciation: Techniques and Methodology, Wiley, N. Y., 2005. J. Buffle, G. Hoarvai (Eds.), In situ Monitoring of Aquatic Systems: Chemical Analysis and Speciation, IUPAC Ser. Anal. Phys. Chem. Environ. Syst., Vol. 6, Wiley, Chichester, UK, 2000. D. M. Templeton, F. Ariese, R. Cornelis, L-G. Danielsson, H. Muntau, H. P. van Leeuwen, R. Łobiński, “Guidelines for terms related to chemical speciation and fractionation of elements. Definitions, structural aspects, and methodological approaches”, Pure Appl. Chem. 72 (2000) 1453- 1470. E. Prichard, G. M. MacKay, J. Points (Eds.), “Trace Analysis: a structured approach to obtaining reliable results”, Royal Society of Chemistry, Cambridge, 1996. Institute for Reference Materials and Measurements (http://www.irmm.jrc.be/html/homepage.htm) The European Virtual Institute for Speciation Analysis (EVISA) (http://www.speciation.net/)

47. Ana BANICA Prøveforelesning 2006 47 Multi pertransibunt et augebitur scientia ‘Many shall pass through and learning shall be increased’ The Great Instauration, Francis Bacon