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Lomonosov Moscow State University Chemistry Department
Division of Analytical Chemistry Aleksandra Zatirakha, Olga Shchukina, Anna Uzhel, Konstantin Smirnov, Alexander Smolenkov, Oleg Shpigun Novel high performance polymer-based anion exchangers for ion chromatography HPLC Congress 2016, London
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Requirements to anion exchangers in IC
Separation of analyte ions Separation from matrix components pH stability (pH 0-14) High chromatographic efficiency Separator columns with different selectivities Solvent compatibility PS-DVB, 55% cross-linking Pellicular structure Attachment of functional layer Electrostatic attachment - latex - ionene Covalent attachment substrate substrate
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Synthesis of chemically derivatized General problem for PS-DVB
anion exchangers General problem for PS-DVB anion exchangers: Multiple stages 2. Time consuming 3. Reproducibility The ways of increasing the efficiency of chemically derivatized anion exchangers Creating pellicular structure Increase of the hydrophilicity Spatial moving of the functional group away from the substrate surface Cooperation of 1, 2 and 3
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Epoxy compounds for a synthesis of anion exchangers
1. Hydrophilization of the functional groups 2. Simultaneous insertion of the linker and functional group 3. Hydrophilic linkers and obtaining of the branched structures 1,4-BDDGE RDGE
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Synthesis of the anion exchangers using epoxy compounds
Polymer: PS-DVB, 55 % cross-linking, particle size 3,3±0,2 µm 5
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Anion exchangers obtained using monoepoxides
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Separation of anions on the anion exchangers with hydrophilic functional groups
With one hydrophilic substitute With two hydrophilic substitutes Columns: 50x4 mm Eluents: I: 15 mМ NaHCO3; II: 1,8 mM Na2CO3 + 1,7 мМ NaHCO3; III: 24 mМ NaHCO3 F=0,8 ml/min 7
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Chromatographic properties of the anion exchangers I, II, III
Eluent: 1,8 mM Na2CO3 + 1,7 mM NaHCO3 Anion Anion exchangers, eluents I, 15 мМ NaHCO3 II, 5 мМ NaHCO3 III 24 мМ NaHCO3 k N As F- 1.8 4500 - 1.2 12000 1.5 5000 Cl- 4.1 4600 2.9 17000 2.7 10000 NO2- 9.0 3400 3.2 4.9 15000 1.9 5.1 13000 Br- 14.7 3600 3.5 7.1 2.3 7.6 1.3 NO3- 27.9 1800 3.9 11.7 8500 2.4 11.1 9000 2.0 HPO42- 6.8 1.4 15.9 35000 1.1 16.1 29000 1.0 SO42- 10.1 6700 21.7 25000 0.9 20.8 8
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Anion exchanger with two hydrophilic substitutes in the functional group (III)
Isocratic elution 5 mM KOH, F=0,7 ml/min Efficiency, N/m NO Br NO Gradient elution 0 – 4,0 min: 5 mМ KOH 4,1 – 5,5 min: 20 mМ KOH 5,6 – 8,0 min: 40 mМ KOH F=0,7 ml/min Columns: 50x4 mm 9
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Separation of anions on the resins with TMA
functional group LogP=- 4.05 LogP=- 5.04 Eluent: 15 мМ NaHCO3; F=0,8 ml/min Eluent: 5 mМ NaHCO3, F=0,8 ml/min 10 Columns: 50x4 mm
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Anion exchangers with distant TMA group
Isocratic mode Eluent: 5 mM KOH, F=0,5 ml/min Efficiency, TP/m NO Br NO Gradient elution mode F=0,5 ml/min 0 – 7 min: 5 mM KOH 7,1 – 10 min: 60 mM KOH 11
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Branched anion exchangers with hydrophilic functional groups
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Branched anion exchangers with hydrophilic functional groups
Linker Amine Capacity, µmole g- LogP of the groupsb BTMA 1,4-BDDGE TMA 586a -14.42 RTMA RDGE 505 -11.68 BDMEA DMEA 919 -16.37 RDMEA 869 -13.62 BMDEA MDEA 364 -18.32 RMDEA 354 -15.56 BTEA TEA 394 -20.27 RTEA 372 -17.51 Substrate: PS-DVB, 55 % cross-linking, particle size 3 µm
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Selectivity of branched anion exchangers modified with 1,4-BDDGE
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Branched anion exchangers modified with 1,4-BDDGE
Efficiency and asymmetry Anion Anion exchanger, eluent BTMA BDMEA BMDEA BTEA N As F- 35000 2.1 46000 1.8 20000 1.6 16000 HCOO- 42000 1.4 56000 - Cl- 51000 1.3 68000 50000 1.1 NO2- 55000 40000 37000 1.5 Br- 38000 53000 49000 NO3- 1.2 SO42- 34000 48000 23000 Separation conditions Columns: 50x4 mm A (TMA): 40 mM KOH B (DMEA): 18 mM KOH C (MDEA): 7 mM KOH D (TEA): 10 mM KOH Flow: 0,5 ml/min
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Selectivity of branched anion exchangers modified with RDGE
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Branched anion exchangers modified with RDGE
Efficiency (N/m) Anion RTMA RDMEA RMDEA RTEA F- 47000 40000 26000 38000 HCOO- 29000 45000 Cl- 41000 28000 37000 NO2- 34000 36000 24000 21000 Br- 20000 12000 NO3- 25000 18000 10000 SO42- 27000 17000 Separation conditions Columns: 50x4 mm A (TMA): 40 mM KOH B (DMEA): 18 mM KOH C (MDEA): 7 mM KOH D (TEA): 10 mM KOH Flow: 0,5 ml/min
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Hyperbranched anion exchangers with
covalently attached functional layer Substrate: EVB-DVB, 55 % cross-linking, particle size 6 µm
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Hyperbranched anion exchangers with
covalently attached functional layer formed by 1,4-BDDGE and methylmine Isocratic mode 3 modification cycles 4 modification cycles Eluent: 5 mM KOH, Flow: 0,5 ml/min Columns: 100 x 4 mm
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Hyperbranched anion exchangers with covalently attached
functional layer 3 cycles 4 cycles Eluent: 5 mM KOH, Flow: 0,5 ml/min Eluent: 25 mM KOH, Flow: 0,5 ml/min Anion F- HCOO- Cl- NO2- Br- NO3- 3 cycles N/m 49500 - 51000 53000 38000 23000 As 1.5 1.4 1.6 1.8 2.3 4 cycles 47000 65000 44000 45000 34000 1.3 1.7 1.9 20
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Hyperbranched anion exchangers with covalently attached
functional layer Gradient mode 3 cycles Eluent: 5-40 mM KOH, F=0,5 ml/min 4 cycles Eluent: mM KOH, F=0,5 ml/min 21
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Selectivity of hyperbranched anion exchangers with
covalently attached functional layer
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Selectivity of hyperbranched anion exchangers with
covalently attached functional layer Factors influencing selectivity Branching degree (number of modification cycles) Hydrophobicity of the linker (diglycidyl ether) Structure of functional site (primary amine)
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Hyperbranched anion exchangers
Column: 100x4 mm Flow rate: 1,0 ml/min Eluent: mM KOH Column: 250x4 mm Flow rate: 1,0 ml/min Eluent: 5-80 mM KOH
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Separation of 7 standard anions, oxyhalides and anions of organic acids with hyperbranched anion exchanger Analytical column 250x4 mm + Guard column 50x4 mm Flow: 1,0 ml/min Eluent: KOH, gradient elution
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Acknowledgements Dr. Olga Shchukina Anna Uzhel, post-graduate
For providing polymers: Dr. Konstantin Smirnov Prof. Andrey Pirogov Consultants: Prof. Alexander Smolenkov Prof. Oleg Shpigun
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Thanks for your attention!
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