Blank Optimization Using Ultrapure Suitable for Trace Ion Analysis. Daniel Darbouret and Ichiro Kano Millipore Corporation Laboratory Division Research and Development BP 307 78054 St Quentin-en-Yvelines Cedex - France IICS - 11th -14th September 2000 - Nice France
Table of Contents Preliminary studies (raw material selection). Materials and methods. Performance of the initial water purification system combining reverse osmosis and electrodeionization. Ionic behavior at each step as well as resulting typical ion chromatograms. Ion chromatography ultratrace analysis on ultrapure water.
Preliminary Studies- Material Extractables 15 C oncentration,µg/l 10 5 0 HDPE1 HDPE2 HDPE3 PP Material chloride nitrite nitra te sulfa te
Preliminary Studies- Material Extractables 1000 C oncentration, µg/l 100 10 1 fluoride chloride nitrite nitra te sulfa te FEP PFA1 PFA2 PFA3 PFA4 PTFE PE PA PU Material
Materials and Methods
Purification Chain Initial purification system Polishing system Reverse osmosis Electrodeionization Storage reservoir polishing unit Municipal RO reject RO permeate EDI concentrate EDI product Ultrapure
Anion Analysis Instrument : Sample volume : Column : Dionex DX 500 - GP50 Pump Autosampler AS40 - CD 20 Conductivity meter - Peaknet software. 25 µl (50-100 - 500-1000 - 5000 ppb) 200 µl (5-10 - 50-100 - 500-1000 ppb) AS12A/AG12A Eluent : 2.7 mm Na 2 CO 3 / 0.3 mm NaHCO 3 Flow rate : 1.5 ml/min. Suppressor : ASRS Ultra - 100 ma recycle mode.
Cation Analysis Instrument : Sample volume : Column : Eluent : Flow rate : Suppressor : Dionex DX 500 - GP50 Pump Autosampler AS40 - CD 20 Conductivity meter - Peaknet software. 25 µl (50-100 - 500-1000 - 5000 ppb) 200 µl (5-10 - 50-100 - 500-1000 ppb) CS12A/CG12A Methanesulfonic acid 20mM. 1.0 ml/min. CSRS Ultra - 50 ma recycle mode.
Instrument : Sample volume : Trace Anion Analysis IC-7000 (Yokogawa Analytical Systems). 0.5 ml (direct injection) or 10 ml (via concentration column) Separation column : ICS-A44/A44G Precolumn : J9199AR Concentration column :ICS-ANC Eluent : 4.0mM Na 2 CO 3 /4.0mM NaHCO 3 Flow rate : 1.0 ml/min. Temperature : 40 ºC
Results
Initial Purification System Initial purification system Polishing system Reverse osmosis Electrodeionization Storage reservoir polishing unit Municipal RO reject RO permeate EDI product EDI concentrate Ultrapure
Initial Purification System Initial purification system Polishing system Reverse osmosis Electrodeionization Storage reservoir polishing unit Municipal RO reject RO permeate EDI product EDI concentrate Ultrapure
Reverse Osmosis Performance Ion concentrations in ppb (µg/l) Tap water RO permeate %reject Conductivity (µs/cm) 569 12.3 97.8 Li 2.9 0.19 93.4 Na 14599 1868 87.2 K 3138 371 88.2 Mg 6438 20 99.7 Ca 106502 584 99.5 F 578 6 99.0 Cl 45477 831 98.2 NO3 13843 1756 87.3 SO4 117546 232 99.8
Reverse Osmosis Performance Cation Study 10000 ppb or µs/cm (- - - - ) 1000 100 10 1 conductivity Li Na K Mg Ca 0.1 0 5 10 15 20 running time (minutes)
Reverse Osmosis Performance Cation Study 5100 ppb 4100 3100 2100 Na K Mg Ca 1100 100 0 5 10 15 20 running time (minutes)
Reverse Osmosis Performance Anion Study 10000 ppb or µs/cm (- - - ) 1000 100 conductivity Fluoride Chloride Nitrate Sulfate 10 0 5 10 15 20 running time (minutes)
Electrodeionization Process Initial purification system Polishing system Reverse osmosis Electrodeionization Storage reservoir polishing unit Municipal RO reject RO permeate EDI product EDI concentrate Ultrapure
EDI Principle A C A C Cathode Anode H + Cl - Na + Cl - OH - Na + _ + Cl - Na + H + Cl - Na + Cl - Na + OH - waste product A - Anion selective Membrane C - Cation selective Membrane
EDI Performance RO permeate EDI conc. EDI dilute Conductivity (µs/cm) 12.3 30.5 < 1 Li 0.8 1.8 < 1 Na 1553 3854 < 1 K 450 988 < 1 Mg 20 51 < 1 Ca 259 664 < 1 F 7 17 < 1 Cl 713 1789 < 1 NO3 1187 3025 < 1 SO4 165 422 < 1 Ion concentrations in ppb (µg/l)
Typical Ion Chromatograms 3 : Tap water ; 2 : RO water ; 1 : RO/EDI water Cations
Typical Ion Chromatograms 3 : Tap water ; 2 : RO water ; 1 : RO/EDI water Anions
Final Polishing Unit (Milli-Q Element) Polishing unit Reverse osmosis Electrodeionization Storage reservoir polishing unit Municipal RO reject EDI product EDI concentrate RO permeate Ultrapure
Ultrapure : Optimized Flow Schematic Elix type Feed UV lamp resistivity cell Automatic footswitch valve pump Purification media PVDF point of use filter UHMWPE point of use filter
Impact of Extractables, Final Filter Conventional PVDF membrane filter C oncentration,µg/l 100 10 1 0.1 0.01 chloride nitra te sulfa te volum e,l 0 2 4 6 UHMWPE optimized membrane filter Concentration,µg/L 10 1 0.1 0.01 chloride nitrate sulfa te volum e,l 0 2 4 6
Final Polishing Unit Results Trace Anion Analysis chloride 100 ng/l phosphate 500 ng/l nitrate 100 ng/l sulfate 100 ng/l nitrite 100 ng/l bromide 100 ng/l Standards Ultrapure water
Final Polishing Unit Results Trace Anion Analysis Ultrapure water Chloride < 10 Nitrite < 10 Phosphate < 50 Bromide < 10 Nitrate < 10 Sulfate < 10 concentration in ng/l (ppt)
Final Polishing Unit Results (ICP-MS) Trace Elemental Analysis DL QL 7 Li 0.026 0.079 0.028 11 B 1.4 4.1 12.9 23 Na 0.094 0.29 0.33 24 Mg 0.012 0.036 0.16 27 Al 0.075 0.23 <DL(0.033) 39 K 2.8 8.6 9.6 40 Ca 3 9 9.1 52 Cr 0.22 0.67 <DL(0.096) 55 Mn 0.25 0.77 0.8 56 Fe 0.048 0.15 0.5 59 Co 0.5 1.5 <DL(0.42) 58 Ni 0.13 0.38 <DL(0.063) 63 Cu 0.075 0.23 <QL(0.13) 64 Zn 2.2 6.6 <DL(1.4) 88 Sr 0.022 0.068 <DL(0.004) 107 Ag 0.076 0.023 0.17 111 Cd 1.3 3.8 <DL(0.67) 138 Ba 0.29 0.89 <DL(0.13) 208 Pb 0.15 0.45 <DL(0.1) All values in ng/l (ppt)
Conclusions In order to minimize the risk of ion contamination, it is recommended to select appropriate raw material, perform extractable studies and choose optimized purification technologies. A combination of reverse osmosis and electrodeionization technologies ensures high and consistent quality of purified water. A final polishing unit consisting of UV photooxidation, high grade purification media and optimized final filter, produces high quality ultrapure water. As a result, combination of all these features can provide ultrapure water suitable for ppt ion chromatography analysis.