Bucharest - September 2010
University of Bucharest, ROMANIA
Iulia Gabriela David, Vasile David, Iulia Gabriela David, Vasile David, Department of Analytical Chemistry, Faculty of Chemistry
Marius Matache, Marius Matache, Centre for Environmental Research and Impact Studies
Bucharest - September 2010
essential elementsessential elements Fe, Se, Cu, Zn Fe, Se, Cu, Zn
toxic metals toxic metals Pb, Cd, Hg, AsPb, Cd, Hg, As
Bucharest - September 2010
Obtain &preserverepresentative
sample
Transform the sample to an analyzable form
Calculate the result
(Input)
(Black box)
(Output)
Bucharest - September 2010
Ialomita River Prut River
Seasonal variations in trace metals concentrations
Quantification of xenobiotics bioaccumulation
in wetland food chains
aimaim
techniquetechnique
ICP-AES ASV
(filtration)
Bucharest - September 2010
-springs from the Southern Carpathians collecting its waters from
hydrographical basin surface area of 10350 km2 (4.4% of the
total area of Romania).
-length of the main collector – Ialomiţa – is 417 km, and of the total
rivers network is 3131 km (4.6 % of the total length of the hydro-
graphic network of the country).
The Ialomiţa gathers the waters of 145 water flows
Bucharest - September 2010
Sampling sessions: Sampling sessions: APRIL –
period of high snow melting in the mountain zones- AUGUST periods of reduced flow and high temperature of the water- NOVEMBER period of high precipitation
Sampling sites:Sampling sites:7 places along Ialomita Riverfrom the axis of maximum turbulence of the river, from the water-sediment interface
Sample preservation:Sample preservation:- in Teflon bottles- concentrated HNO3 added to avoid analytes losses
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 Bucharest– Ploieşti, possible pollution
sources: Pucioasa city, thermo-electric power station Doiceşti, Târgovişte city with the special steel aggregate works4 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
Bucharest - September 2010
Bucharest - September 2010
Modell 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
Bucharest - September 2010
Sampling sessions: Sampling sessions: Spring - april 2009Summer - july 2009
Sampling: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:Sample preservation:- in Teflon bottles- concentrated HNO3 added to avoid analytes losses
1. Upstream of the Maţa-Rădeanu complex water quality at the entrance of the Prut river into
the Lower Prut Floodplain Natural Park2. Downstream of the Rogojeni village influence
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 lakesimpact 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 Tuluceşti covers a region including the loop Cotul Hiului and some
localities on the left river side and Beleu lake6.Upstream of Prut’s run into the Danube finalsampling point----- influence of Brateş lake, of
agricultural fields-gives an image of pollutants concentrations
transferred by Prut into the Danube Bucharest - September 2010
Bucharest - September 2010
Bucharest - September 2010
SCHEMATIC OF AN ICP-AESpectrometer
Nebuliser
Ar
excited atoms
hDetector
Polychromator
(Ar+sample aerosole)
(T=8000Kh=12 cm)
(cooling, 12 L/min)
(0.8 L/min)
(1 L/min)
Sample(0.002 l/min)
(Frequency 27.12 MHz Power adjustable 800 -1,600 W)
(165–210 nm;210-580 nm)
Plasma torch
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
- high Ar consumption-expensive instrumentation
Bucharest - September 2010
-HMDE-MFE-Bare C, Au, etc.
10-4 -10-5 Hg+2 for co-metal deposition.
A cathodic or reducingpotential is applied for afixed time interval reducing Mn+
Potential is scannedin anodic or oxidizingdirection to strip out Mo
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 measuring20% - 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.
•Simultaneous metal ions analysis.
No interference between: Pb, Cd, Cu and Hg Zn, Pb, Cd and Hg Zn and Cu at low concentrations
(higher concentrations + Ga3+ )Interferences:
Tl - with Cd, Pb Bi - with Cu (at conc > 50 times)
Aplications to saline solutions: unlike Graphite AA techniques, salinity does not impact the accuracy or performance of the metals measurement
Bucharest - September 2010
CuPb
Zn
Cd
Ga
Bucharest - September 2010
Sample pretreatment•In General: no electrode rotation or sample de-oxygenation. •Clean samples: only addition of a supporting electrolyte. •Biological, Soil, Seawater and Dirty-Water:
• filtration• wet acid digestion (+ UV digestion).
•Cost of ultra-sensitive instrumentation. A quarter of the cost of AA systems A tenth of the cost of ICP systems Use one electrode to measure up to five metals Robust electrodes can make thousands of measurements; can use disposabel electrodes (PGE) Small, field devices – cheap !!!
Bucharest - September 2010
•Selectivity & sensitivity can be improved by electrode surface modification e.g.:-Bi deposition on GCE (DL=1.4×10-10 mol/L Pb²+; 0.03 μg/L)
[C. E. Cardoso et.al. Anal. Sci., 23, 1065, 2007]
-Heparin modified GCE (DL= 3×10-10 mol/L Pb²+; 0.06 μg/L) [N.-B. Li, J.-P. Duan, G.-N. Chen, Chin. J. Chem., 22, 553, 2004]
-Polyethacridine film modified GCE (PFM-GCE)
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 lactateSurface cleaning: - 5 minutes in 0,1 M HNO3 at 0.100 VMetal ions determination Technique: -AS-DPV Medium: - 0.1 M HNO3 Accumulation:Eac= -1.2 V vs g/AgCl
tac= 120 s (C <10-7 mol/L Cd²+ )
ResultsResultsBare 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 Cd²+
DL= 5 10-8 mol/L Cd²+ 8 10-9 mol/L Cd²+ 5 10-9 mol/L Cd²+
Bucharest - September 2010
Variation of Zn and Mo concentration in water samples from the Ialomiţa River
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: tac = 120 s, Eac= -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
Bucharest - September 2010
DP-anodic stripping voltammograms recorded in HNO3 0,1 M on
MF-GCE for sample 6 collected upstream of Prut’s run in theDanube: (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.
Bucharest - September 2010
Me(II)sample
Cu(II) (g/L) Pb(II) (g/L) Cd(II) (g/L)
apriljuly
apriljuly
apriljuly
pr1 3.20 10-61.30 10-5 3.00 10-6
<LOD 2.10 10-5<LOD
pr2 6.74 10-51.60 10-5 5.66 10-7
2.60 10-4 1.61 10-5<LOD
pr3 1.93 10-54.10 10-5 1,83 10-5
1.80 10-5 3.30 10-51.20 10-4
pr4 3.88 10-5<LOD <LOD <LOD 1.48 10-4
<LOD
pr5 9.20 10-69.50 10-6 <LOD <LOD 5.15 10-5
<LOD
pr6 6.70 10-62.50 10-5 8.60 10-6
<LOD 1.09 10-4<LOD
Heavy metals concentration in Prut River Water Samples
Bucharest - September 20109
SeparationSeparation 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 collected on 29.07.2009, at sampling point 6, where Prut runs into Danube).
Bucharest - September 2010
-1.50E-02
-1.00E-02
-5.00E-03
0.00E+00
-1000 -800 -600 -400 -200 0
i (A
)
E (mV)
X4
X41
X42
DP-anodic stripping voltammograms recorded in HNO3 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.
Bucharest - September 2010
Acknowledgement
Financial support is acknowledged from the
PN-II- project BIOXEN 32111-2008.
Bucharest - September 2010
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