MULTI PHYSICAL-CHEMICAL PROFILER FOR REAL-TIME CONTINUOUS IN SITU

MULTI PHYSICAL-CHEMICAL PROFILER FOR REAL-TIME CONTINUOUS IN SITU MONITORING OF SPECIFIC FRACTIONS OF TRACE METALS AND MASTER VARIABLES DE L’ENVIRONNEMENT Marylou Tercier-Waeber 1, Fabio Confalonieri 2, Giuliano Riccardi 2, Antonio Sina 2, Flavio Graziottin 2, Jacques Buffle 1 1 Dept. of Inorganic and Analytical Chemistry, University of Geneva, 30 Quai E. Ansermet, 1211 Geneva 4, Switzerland. 2 Idronaut Srl, Via Monte Amiata 10, Brugherio (MI), Italy. CHIMIE ANALYTIQUE ET BIOPHYSICOCHIMIE IDRONAUT Contact: Marie-Louise. Tercier@cabe. unige. ch INTRODUCTION Development of novel analytical tools allowing real-time and detailed temporal/spatial evolution monitoring of the distribution of specific metal species and master variables is of prime interest. They will enable us to better understand the role and the fate of trace metals in aquatic systems, to develop more accurate predictive models based on biogeochemical processes, to evaluate the impact of human activity on coastal ecosystems and therefore to optimize industrial/social developments. With these goals in mind, we recently started the development of an automated Multi Chemical-Physical Profiler (MPCP). The MPCP is based on the Voltammetric In situ Profiling System (VIP System), which was developed during an European MAST-III project and is now commercialised by Idronaut. The VIP probe is based on a gel integrated microelectrode (GIME) which allows the specific measurement of the concentration of the dynamic fraction of trace metals, defined as the sum of the free metal ions and the small labile complexes with size of few nanometers. The following analytical and technical developments are under way to improve the capability of the VIP probe: . Development of a novel chelating resin-gel integrated microsensor (CGIME) for in situ measurements of free metal ion concentrations Land Station Buoy Profiler Development of a submersible FIA system coupled to one cell for in situ measurements of total extractable metal concentrations Development of an improved VIP voltammetric probe based on 3 flow-through cells and three individual potentiostats (MPCP voltammetric probe) for simultaneous in situ measurements of the above three specific fractions of trace metals Incorporation of the MPCP voltammetric probe with external/integrated probes for measurements of master variables into a buoy supported automated monitoring system which can be controlled from a land station. MULTI PHYSICAL-CHEMICAL PROFILER MAIN COMPONENTS Schematic diagram of the gel-integrated microsensors Schematic diagram of the MPCP harware Submarine connectors for: Telemetry, Serial interface, FIA, Fluorescence probe 100 -interconnected Ir-microdisk electrode array electrical contact epoxy resin Al or Au bonding GIME (MPCP cells 1 and 3) CGIME (MPCP cell 2) containment ring Agarose gel Mercury layer Chelating resin Si 3 N 4 Ir Si 3 N 4 Silicon 150 µm 4 mm Agarose gel Mercury layer Si 3 N 4 Ir Si 3 N 4 Silicon Main CPU board FSK telemetry board Fluidic & FIA device drive board Multiparameter probe board Smart potentiostat boards 5 µm Mother board & Power supply Mechanical & signal connectors VIP cell 1. 8 mm Preamplifier Cell-2 CGIME Schematic diagram of the submersible FIA and example of analytical conditions used for measurements of total extractable metal concentrations in Arve river samples. Cell-1 GIME MPCP management software Integrated multiparameter probe p. H 2, 15 min FIA, 15 min p. H 2, 62 h 100 To VIP cell 0. 03 M HNO 3 2. 3 ml/min ACID LIGAND 150 µM TRIEN Sample + L + Acid eq. t = 5 min; Tf = 22°C Cooling coil (V = 4. 5 ml/min) Example of voltammogram obtained by measurements in Arve river sample using GIME sensor 60 40 20 Sample + L + Acid eq. t = 5 min; T = 60°C Sample + L eq. t = 5 min; T = 20°C Raw Arve sample 2. 3 ml/min 4. 12. 2001 80 Heating coil ( V = 4. 5 ml) 2. 3 ml/min Cell-3 FIA-GIME Mixing coil (V = 4. 5 ml) 0 Cu/Cutot Pb/Pbtot Ratios of total extractable Me conc. (voltammetry) to total Me conc. (ICP-MS ) obtained in an Arve river sample after sample pre-treatments based on: i) acidification and ii) ligand exchange followed by acidification and heating of the sample. The MPCP probe harware and firmware have been developed to allow simultaneous measurement cycles on the three channels. PRELIMINARY FIELD TESTS OF THE MPCP Channel 2 Channel 3 Av. conc. RSD % 11 h 30 12 h 30 13 h 30 14 h 30 15 h 30 4. 91 5. 14 4. 39 4. 74 4. 30 4. 79 4. 51 4. 59 - 5. 36 4. 45 4. 27 4. 36 4. 28 4. 85 4. 79 4. 39 4. 57 - 10. 93 7. 10 2. 73 4. 16 - Av. conc. RSD % 4. 69 7. 46 4. 55 4. 57 4. 54 10. 10 4 Pontoon 3. 5 m-21 Ingela's 5 m-22 Ingela's 30 m-22 Alsbäck 5 m-23 Alsbäck 35 m-23 Ingela's 5 m-26 140 120 100 80 60 40 20 0 Ingela's 30 m-26 Pontoon 3. 5 m-21 Ingela's 5 m-22 Channel 3 Av. conc. 0. 43 0. 46 0. 39 0. 43 0. 44 0. 42 0. 34 0. 40 - 0. 48 0. 37 0. 41 0. 36 0. 45 0. 37 0. 41 - Av. conc. RSD % 0. 43 5. 81 0. 43 9. 76 RSD % 0. 42 11. 91 5. 78 6. 86 3. 70 - 3 Pbtot p. H 2 2 h Pbtot FIA 7 min Pbdyn VIP/MPCP Pbfree CGIME Ingela's 30 m-22 Alsbäck 5 m-23 35 m-23 Ingela's 5 m-26 Ingela's 30 m-26 2. 5 2 1. 5 1 0. 5 0 Conc. of Cd dynamic fraction (n. M) Channel 2 Channel 3 Av. conc. 11 h 30 12 h 30 13 h 30 14 h 30 15 h 30 0. 17 0. 19 0. 17 0. 22 0. 20 0. 22 0. 19 0. 23 - 0. 21 0. 17 0. 21 0. 19 - 10. 31 11. 30 10. 32 - Av. conc. RSD % 0. 19 11. 05 0. 21 8. 57 0. 20 9. 01 Ingela's 5 m-22 RSD % Typical example of the measurement reproducibility of the individual channels and between the three channels of the MPCP voltammetric probe obtained for in situ autonomous measurements over 5 hours using one GIME sensor in each MPCP probe channel. Kristineberg pontoon August 22 2002, deployment depth 3. 5 m, SWASV measurement time 20 min. Ingela's 30 m-22 Alsbäck 5 m-23 Alsbäck 35 m-23 Ingela's 5 m-26 Ingela's 30 m-26 120 100 Alsbäck 5 m-23 35 m-23 Ingela's 5 m-26 Ingela's 30 m-26 80 60 40 20 0 Pontoon 3. 5 m-21 Ingela's 5 m-22 Ingela's 30 m-22 Example of Cu and Pb specific fraction concentrations measured in Gullmarsfjorden stations, August 21 -26 2002 Temperature (°C) 0 Depth (m) Channel 1 Pontoon 3. 5 m-21 Pbtot FIA 7 min Pbdyn VIP/MPCP Pbfree CGIME 0 5 10 15 20 25 30 35 40 10 20 30 40 50 60 Ingela’s 22. 08. 02 Temperature (°C) Salinity (psu) 0 0 5 10 15 20 25 30 35 40 20 40 60 80 100 120 0 Depth (m) Channel 2 time Preliminary field tests of the MPCP analytical and technical developments have been performed during a campaign performed at Kristineberg Marine Station – Sweden, August 19 -28 2002. The MPCP system integrating 3 GIME sensors was deployed, together with VIP systems, in Gullmarsfjorden at various locations and depths. Laboratory measurements of total extractable Me and free Me ion concentrations using a FIA prototype coupled to the MPCP channel 3 and a CGIME sensor respectively were performed in freshly collected samples. 6 Cutot FIA 7 min Cudyn VIP/MPCP Cufree CGIME 140 Conc. of Pb dynamic fraction (n. M) 11 h 30 12 h 30 13 h 30 14 h 30 15 h 30 Entrance of Gullmarsfjorden 8 0 Channel 1 Kristineberg Marine Station 10 2 Concentration (n. M) time 12 Concentration (n. M) Channel 1 Cutot p. H 2 2 h Cutot FIA 7 min Cudyn VIP/MPCP Cufree CGIME Cu specific fractions / Cutot p. H 2 (%) 14 Conc. of Cu dynamic fraction (n. M) Depth (m) time Measurements of trace metal speciation and master variables in Gullmarsfjorden Pb specific fractions / Pbtot p. H 2 (%) Reproducibility of the MPCP voltammetric probe 0 Salinity (psu) 5 10 15 20 25 30 35 40 10 20 30 40 Alsbäck 23. 08. 02 50 60 Typical temparature and salinity profiles measured in two stations of Gullmarsfjorden Ingela’s 26. 08. 02 ACKNOWLEDGEMENTS The authors thank: Olivier Guenat and Milena Koudelka-Hep, IMT - University of Neuchâtel, who produce and supply the Ir-interconnected microelectrode arrays used to prepare the GIME and CGIME sensors; David Turner, AMK-University of Göteborg, for all facilities during field work in Sweden; the financial support of the European Commission and the OFES – Switzerland (European EESD program- IMTEC project Contract n° EVK 3 -CT-2000 -00036).