David diaspora

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  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • KontakTUM Seminar -Singapore 2009
  • David diaspora

    1. 1. Bucharest - September 2010 University of Bucharest, ROMANIA Iulia Gabriela David, Vasile David, Department of Analytical Chemistry, Faculty of Chemistry Marius Matache, Centre for Environmental Research and Impact Studies
    2. 2. Bucharest - September 2010  essential elements Fe, Se, Cu, Zn   toxic metals Pb, Cd, Hg, As
    3. 3. Bucharest - September 2010 Obtain &preserve representative sample Transform the sample to an analyzable form Calculate the result (Input) (Black box) (Output)
    4. 4. Bucharest - September 2010 Ialomita River Prut River Seasonal variations in trace metals concentrations Quantification of xenobiotics bioaccumulation in wetland food chains aim technique ICP-AES ASV
    5. 5. (filtration)
    6. 6. Bucharest - September 2010 <ul><li>springs from the Southern Carpathians collecting its waters from </li></ul><ul><li>hydrographical basin surface area of 10350 km 2 (4.4% of the </li></ul><ul><li>total area of Romania). </li></ul><ul><li>-length of the main collector – Ialomiţa – is 417 km, and of the total </li></ul><ul><li>rivers network is 3131 km (4.6 % of the total length of the hydro- </li></ul><ul><li>graphic network of the country). </li></ul><ul><li>The Ialomiţa gathers the waters of 145 water flows </li></ul>
    7. 7. Bucharest - September 2010 <ul><li>Sampling sessions: </li></ul><ul><li>APRIL – </li></ul><ul><li>period of high snow melting in the mountain zones </li></ul><ul><li>AUGUST </li></ul><ul><li>periods of reduced flow and high temperature of the water </li></ul><ul><li>NOVEMBER </li></ul><ul><li>period of high precipitation </li></ul>Sampling sites: 7 places along Ialomita River from the axis of maximum turbulence of the river, from the water-sediment interface Sample preservation: - in Teflon bottles - concentrated HNO 3 added to avoid analytes losses
    8. 8. Bucharest - September 2010 Hydrographical basin of the Ialomiţa river with indications of the sampling points. 1 Pietroşiţa – upstream of any pollution source - natural background 2 Pucioasa – downstream from the Pucioasa reservoir lock -> contribution of 2 economic operators – the cement factory + light sources factory Fieni . 3 Ciolpani – characterises the region Pucioasa reservoir lock and DN 1 Buc harest – Ploieşti , possible pollution sources : Pucioasa city , thermo - electric p ower station Doiceşti, Târgovişte city with the special steel aggregate works 4 Dridu – downstream from the Dridu reservoir lock – characterises region of agricultural activities; 5 Albeşti – Urziceni town , live-stock farms Căzăneşti, contribution of the Prahova river; 6 Bucu – Slobozia twon with chemical fertilizers aggregate works, 7 Vlădeni – Ţăndărei town Doiecesti  Targoviste 
    9. 9. Bucharest - September 2010
    10. 10. Bucharest - September 2010 Model l for the disturbance of ecological balance in wetlands (CCMESI, 2008) Bioaccumulation of heavy metals and/or pescticides along food chains Domestic, industrial and agricultural waste waters; organic substances; nutrients Excessive exploitation of fisheries resources Toxic atmospheric inputs: NOX, SX, heavy metals Uncontrolled hunting; Poaching Uncontrolled deforestation Excess of nutrients for fisheries
    11. 11. Bucharest - September 2010 Sampling sessions: Spring - april 2009 Summer - july 2009 Sampling: 6 sampling places along the Romanian side of Prut River from the axis of maximum turbulence of the river, from the water-sediment interface Sample preservation: - in Teflon bottles - concentrated HNO 3 added to avoid analytes losses
    12. 12. 1. Upstream of the M aţa-Rădeanu complex water quality at the entrance of the Prut river into the Lower Prut Floodplain Natural Park 2. Downstream of the Rogojeni village in fluence of some pollution sources: Maţa-Rădeanu complex, Pochina lake , Cacia and Leahu pools , Broscarului and Teleajen lakes and the localities Vădeni and Rogojeni 3. Downstream of Vlădeşti and Măicaşu lakes impact of the two lakes, of Şovârca pool and localities Oancea, Slobozia-Oancea and Vlădeşti 4.Downstream of Vlăşcuţa lake influence of lakes Brăneşti , Vlăşcuţa, and of Manta lake on the left side of Prut ( Moldova Rep ), and localities Brăneşti and Măstăcani 5.Downstream of Beleu, at Tuluceşt i co vers a region including the loop Cotul Hiului and some localities on the left river side and Beleu lake 6. Upstream of Prut ’s run into the Danube final sampling point-----  influence of Brateş lake, of agricultural fields -gives an image of pollutants concentrations transferred by Prut into the Danube Bucharest - September 2010
    13. 13. Bucharest - September 2010
    14. 14. Bucharest - September 2010 SCHEMATIC OF AN ICP-AESpectrometer Nebuliser Ar excited atoms h  Detector Polychromator (Ar+sample aerosole) (T=8000K h=12 cm) (cooling, 12 L/min ) (0.8 L/min) (1 L/min) (Frequency 27.12 MHz Power adjustable 800 -1,600 W) (165–210 nm; 210-580 nm) Plasma torch Sample (0.002 l/min)
    15. 15. Bucharest - September 2010 -low detection limits for over 70 elements (ppb) [ e.g. 10 ppb for Pb; 50 ppb for As ] -PDA detectors enable simultaneous multielemental analysis -enables automatisation  high sample throughput : 1-3 minutes for a complete analysis of 30 elements <ul><li>- high Ar consumption </li></ul><ul><li>expensive instrumentation </li></ul>
    16. 16. Bucharest - September 2010 -HMDE -MFE -Bare C, Au, etc. 10 -4 -10 -5 Hg +2 for co-metal deposition. A cathodic or reducing potential is applied for a fixed time interval reducing M n+ Potential is scanned in anodic or oxidizing direction to strip out M o
    17. 17. Bucharest - September 2010 • Sensitive and reproducible (RSD<5%) method for trace metal ion analysis in aqueous media. Accuracy is proportionate to the way of sample calibration: <5% when calibrated directly via the method of standard additions. 10% when a calibration curve is built before measuring 20% - 40% when operating uncalibrated • Concentration limits of detection for many metals are in the low ppb to high ppt range (S/N=3) ppm - instantaneous ppb < 30 seconds or less ppt - several minutes  compares favorably with AAS or ICP analysis.
    18. 18. <ul><li>• Simultaneous metal ions analysis . </li></ul><ul><li> No interference between: </li></ul><ul><li>Pb, Cd, Cu and Hg </li></ul><ul><li>Zn, Pb, Cd and Hg </li></ul><ul><li>Zn and Cu at low concentrations </li></ul><ul><li> (higher concentrations  + Ga3+ ) </li></ul><ul><li>Interferences: </li></ul><ul><li>Tl -  with Cd, Pb </li></ul><ul><li> Bi -  with Cu (at conc > 50 times) </li></ul><ul><li> Aplications to saline solutions: unlike Graphite AA techniques, salinity does not impact the accuracy or performance of the metals measurement </li></ul>Bucharest - September 2010 Ga Cu Pb Zn Cd
    19. 19. Bucharest - September 2010 <ul><li>Sample pretreatment </li></ul><ul><li>In General: no electrode rotation or sample de-oxygenation. </li></ul><ul><li>Clean samples:  only addition of a supporting electrolyte. </li></ul><ul><li>Biological, Soil, Seawater and Dirty-Water: </li></ul><ul><ul><ul><li>filtration </li></ul></ul></ul><ul><ul><ul><li>wet acid digestion (+ UV digestion). </li></ul></ul></ul><ul><li>• Cost of ultra-sensitive instrumentation. </li></ul><ul><li>A quarter of the cost of AA systems </li></ul><ul><li>A tenth of the cost of ICP systems </li></ul><ul><li>Use one electrode to measure up to five metals </li></ul><ul><li>Robust electrodes can make thousands of measurements; can use disposabel electrodes (PGE) </li></ul><ul><li>Small, field devices – cheap !!! </li></ul>
    20. 20. Bucharest - September 2010 <ul><li>• Selectivity & sensitivity can be improved by electrode surface modification e.g.: </li></ul><ul><li>Bi deposition on GCE (DL= 1 . 4×10 -10 mol/L P b² + ; 0.03 μ g/L) </li></ul><ul><li>[ C. E. Cardoso et.al. Anal. Sci., 23, 1065, 2007 ] </li></ul><ul><li>Heparin modified GCE (DL= 3 ×10 -10 mol/L P b² + ; 0.06 μ g/L) </li></ul><ul><li>[ N.-B. Li, J.-P. Duan, G.-N. Chen, Chin. J. Chem ., 22, 553, 2004 ] </li></ul><ul><li>-Polyethacridine film modified GCE (PFM-GCE) </li></ul>Ethacridine lactate (Rivanol) Film preparation : -5 CV cycles (0-1,5 V vs AgAgCl); v=100 mV/s - ABS (pH=5.00) + 10 -2 M ethacridine lactate Surface cleaning: - 5 minutes in 0,1 M HNO3 at 0.100 V Metal ions determination Technique: -AS-DPV Medium: - 0.1 M HNO3 Accumulation: E ac = -1.2 V vs g/AgCl t ac = 120 s (C <10 -7 mol/L Cd ² + ) Results Bare GCE MF-GCE PFM-GCE LR= 5 10 -7 – 10 -5 mol/L 2.2 10 -8 – 10 -6 mol/L 10 -8 -10 -5 mol/L Cd ² + DL= 5 10 -8 mol/L Cd ² + 8 10 -9 mol/L Cd ² + 5 10 -9 mol/L Cd ² +
    21. 21. Bucharest - September 2010 Variation of Zn and Mo concentration in water samples from the Ialomiţa River
    22. 22. Bucharest - September 2010 Technique : Differential Pulse Anodic Stripping Voltammetry (DP-ASV) Working electrode : Mercury film deposited on a glassy carbon electrode (MF-GCE) Optimum conditions : t a c = 120 s, E ac = -1,1 V; v = 20 mV/s, Pulse amplitude = 50 mV; Sampling width = 20 ms; Pulse width = 40 ms; Pulse periode = 300 s Concentration evaluation method : Standard addition Analyte : Cu(II), Pb(II), Cd(II) from Prut River water samples and mollusks
    23. 23. Bucharest - September 2010 DP-anodic stripping voltammograms recorded in HNO 3 0,1 M on MF-GCE for sample 6 collected upstream of Prut’s run in the Danube: (6b-5)=water sample 6; (6b-6)= water sample 6 + 0,1 mL standard solution; (6b-7)= water sample 6 + 0,2 mL standard solution containing Cu(II) = Cd(II)= Pb(II)= 8 10 -3 g/L.
    24. 24. Bucharest - September 2010 Heavy metals concentration in Prut River Water Samples Me(II) sample Cu(II) (g/L) Pb(II) (g/L) Cd(II) (g/L) april july april july april july pr1 3.20 10 -6 1.30 10 -5 3.00 10 -6 <LOD 2.10 10 -5 <LOD pr2 6.74 10 -5 1.60 10 -5 5.66 10 -7 2.60 10 -4 1.61 10 -5 <LOD pr3 1.93 10 -5 4.10 10 -5 1,83 10 -5 1.80 10 -5 3.30 10 -5 1.20 10 -4 pr4 3.88 10 -5 <LOD <LOD <LOD 1.48 10 -4 <LOD pr5 9.20 10 -6 9.50 10 -6 <LOD <LOD 5.15 10 -5 <LOD pr6 6.70 10 -6 2.50 10 -5 8.60 10 -6 <LOD 1.09 10 -4 <LOD
    25. 25. Bucharest - September 2010 9 Separation Shell Soft part Washing Weighing Adding 5 ml HNO3 (65%) 5 ml HCl (35-37%) 5 ml HClO4 Heating to dryness Adding 5 ml HNO3 (65%) 5 ml HCl (35-37%) Heating Filtering Diluting with MilliQ H2O to the mark of a 25 ml volumetric flask Lymnaea stagnalis , ( sample X 5 col l ect ed on 29.07.2009 , at sampling point 6, where Prut runs into Danube ).
    26. 26. Bucharest - September 2010 DP-anodic stripping voltammograms recorded in HNO 3 0,1 M on MF-GCE for dissoluted mollusk sample X4 ( Lymnaea stagnalis) collected upstream of Prut’s run in the Danube: (X4)=dissoluted mollusk sample; (X41)= dissoluted mollusk sample + 0,1 mL standard solution; (X42)= dissoluted mollusk sample + 0,2 mL standard solution containing Cu(II) = Cd(II)= Pb(II)= 8 10 -3 g/L.
    27. 27. Bucharest - September 2010 Acknowledgement Financial support is acknowledged from the PN-II- project BIOXEN 32111-2008.
    28. 28. Bucharest - September 2010

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