theory of ion chromatography - · pdf fileic_theory_20041011_e.ppt 1 ic ic ic ic ic an...
TRANSCRIPT
ic_theory_20041011_e.ppt 1
IC ICIC IC
IC
An introduction to Ion ChromatographyAn introduction to Ion Chromatography
Theory of IC
K. H. ViehwegerMetrohm AG, Herisau, Switzerland
ic_theory_20041011_e.ppt 2
IC ICIC IC
IC
What is chromatography? What is chromatography? about history and physical chemistry
Where does the chromatography actually happen?Where does the chromatography actually happen?from ion exchange to ion pairs
Which detection can be used?Which detection can be used?from voltammetry to conductivity
What is suppressed ion chromatography?What is suppressed ion chromatography?from high to low backgrounds
ChromatographyChromatographyfrom beginners to experts
ContentContent
Theory of IC
ic_theory_20041011_e.ppt 3
IC ICIC IC
IC
DefinitionDefinition«An analytical method where a substance mixture appearing in just one colour is separated in a way that different colours become visible. The method is used to separate chemical substances which are chemically quite similar and though difficult to separate»
Greekchroma = colourgraphein = to write
HistoryHistory
Theory of IC
ic_theory_20041011_e.ppt 4
IC ICIC IC
IC
185019351942
1947195319571959
1967-701975
1979
1976-80
topsoilssulfonated and aminated polymerssulfonated polystyrene/divenylbenzene resins(Manhattan project)aminatedion exclusion chromatographymacro pore iotheoretical backgroundpelicular ion exchange materialsion exchange chromatography wdetectioconducsuppressionion pair chromatography
as ion exchanger for Mg2+, Ca2+ and NH4+
PS/DVB resins as ion exchanger
n exchanger
ith conductivity n and stripper (suppressor)
tivity detection with electronic
Thomson, WayAdams, Holmsd’Alelio
McBurneyWheaton, BaumannCorte, Meyer et al.HelfferichHorvath, KirklandSmall, Stevens
Gjerde, Fritz
Waters, Bidlingmeier, et. al
, Baumann
, Schmuckler
LC
HPLC
HistoryHistory
Theory of IC
ic_theory_20041011_e.ppt 5
IC ICIC IC
IC
take a piece of papermake a little drop with «black» ink
just add water to it’s centersee the colors that make up
the «black»ink
Going back to schoolGoing back to school
Chromatography
A simple experiment from schoolA simple experiment from school
ic_theory_20041011_e.ppt 6
IC ICIC IC
IC
DefinitionDefinition«The term «chromatography» is the general name for a wide range of physico-chemical separation processes in which the components to be separated are distributed between a stationary and a mobile phase.»
gaseousmobile phasemobile phase liquidstationary phasestationary phase liquid → GLC, LLC
solid → GSC, LSC(HPLC - IC)
Physico Physico chemicalchemical
Chromatography
ic_theory_20041011_e.ppt 7
IC ICIC IC
IC
Types of chromatographyTypes of chromatography
Mobile phase dissolves and transports the analyteStationary phase retains the analyte
adsorbing ⇒ adsorption chromatography
dissolving ⇒ distribution chromatography
reacting ⇒ ion exchangechromatography
Column interactionsColumn interactions
Chromatography
ic_theory_20041011_e.ppt 8
IC ICIC IC
IC
Methods of chromatographyMethods of chromatographyBased on the polarities of the stationary and mobile phases a distinction is made between the following methods:
Group 1 – traditional TLC + HPLC1. normal phase chromatography2. reversed phase chromatographyGroup 2 – Ion Chromatography4. ion exchange chromatography3. ion pair chromatography5. ion exclusion chromatography
PolaritiesPolarities
Chromatography
ic_theory_20041011_e.ppt 9
IC ICIC IC
IC
Group 1 Group 1 –– traditional TLC + HPLCtraditional TLC + HPLC1. Normal phase chromatographyStationary p. = polar (e.g. SiO2) –mobile p. = non polar (e.g. n-hexane)
2. Reversed phasechromatography
Stationary p. = non-polar (e.g. C18) –mobile p. = polar (e.g. acetonitrile or methanol/water)
Traditional methodsTraditional methods
Chromatography
ic_theory_20041011_e.ppt 10
IC ICIC IC
IC
Group 2 Group 2 –– ICIC4. Ion exchange chromatographyCations and anions form a weak ionic binding with the stationary phase.C: Stationary p. = polar (e.g. R-SO3
–) – mobile p. = polar (e.g. HNO3 aq.) orA: Stationary p. = polar (e.g. R-NR3
+) – mobile p. = polar (e.g. Na2CO3 aq.)
IC methodsIC methods
Chromatography
ic_theory_20041011_e.ppt 11
IC ICIC IC
IC
Group 2 Group 2 –– ICIC3. Ion pair chromatographyCations and anions react to a non-ionic molecule by adding a lipophilic counter ion. The resulting non-polar molecules are then separated in the RP-mode.Stationary p. = non-polar (e.g. C18) – mobile p. = polar (e.g. acetonitrile or methanol/water)
IC methodsIC methods
Chromatography
ic_theory_20041011_e.ppt 12
IC ICIC IC
IC
Group 2 Group 2 –– ICIC5. Ion exclusion chromatographyBy adding H+-ions the stationary phase is transformed into a non ionic but polar Donan membrane. Only non dissociated molecules can enter this membrane. If they dissociate they are excluded from the stationary phase. The separation is though depending on the dissociation constant of the respective molecules.– mobile p. = polar (e.g. H2SO4 aq.)
IC methodsIC methods
Chromatography
ic_theory_20041011_e.ppt 13
IC ICIC IC
IC
DefinitionDefinition«Ion chromatography includes all chromatographic methods that separate ionic substances and substances that dissociate easily. These methods are ion pair chromatography (3), ion exchange chromatography (4) and ion exclusion chromatography (5). Analyte and mobile phase are initially always polar and/or ionic. Ion exchange chromatography is the most important separation mechanism in ion chromatography.»
ResumeResume
Chromatography
ic_theory_20041011_e.ppt 14
IC ICIC IC
IC
LiquidLiquid--solidsolid--chromatographychromatographySince the introduction of high pressure or high performance chromatography (HPLC) at the end of the sixties, liquid chromatography has developed into one of the most comprehensive and important methods of modern instrumental analysis. Ion chromatography is an «aliquot» of the HPLC-family.
[mobile phase = liquid and stationary phase = solid]
HPLC and ICHPLC and IC
Chromatography
ic_theory_20041011_e.ppt 15
IC ICIC IC
IC
Eluent Pump Injector ColumnSuppressor
Detector
Most popular set upMost popular set up
Chromatography
ic_theory_20041011_e.ppt 16
IC ICIC IC
IC
Eluent Pump Injector Column Detector
Where does it actually happen?Where does it actually happen?
Chromatography
ic_theory_20041011_e.ppt 17
IC ICIC IC
IC
The stationary phaseThe stationary phaseCations need a cation exchanger and anions need an anion exchangerHow a stationary phase is built
Styrene
Divinylbenzene
Cationexchanger
Ion exchangeIon exchange
Chromatography
⇒ ⇒
Styrene-divinylbenzene resinAnionexchanger
ic_theory_20041011_e.ppt 18
IC ICIC IC
IC
Composition of the Composition of the stationary phasestationary phase
SubstratesPolystyrene/divinylbenzenePolymethacrylatePolyalcoholHydroxyethylmethacrylate (HEMA)Silicate
Anion exchangerquaternary ammonium groupsalkyl amineshydroxy-alkylaminesalkyl amines with acrylate type crosslinking
Ion exchangeIon exchange
Chromatography
substrate / resin carriera spacer groupa group that carries the separating capacity
Cation exchangersulfonatescarboxylates
Spaceralkyl chain
ic_theory_20041011_e.ppt 19
IC ICIC IC
IC
Mobile PhaseMobile PhaseThe mobile phase dissolves and carries the sampleThe mobile phase is usually aqueous
anions (I)Phthalic acidSalicylic acid p-Hydroxybenzoic acidBenzoic acidBorateBorate/GluconatePotassium hydroxide
...
anions (II)Carbonat/bicarbonatePotassium hydroxideBoratecations (I)
Nitric acidTartaric acidTartaric acid/dipicolinic acid Tartaric acid/citric acidSodium dihydrogene phosphateoxalic acid/ethylene diamine/acetone
...
Ion exchangeIon exchange
Chromatography
ic_theory_20041011_e.ppt 20
IC ICIC IC
IC
Ion exchangeIon exchange
Chromatography
CationCation separation mechanismseparation mechanismStationary phase and mobile phase compete for the analyte
ic_theory_20041011_e.ppt 21
IC ICIC IC
IC
C2 – 250Tartaric-/dipicolinic acid/crown
ether; 4/0.45/0.05 mmol/L1 Lithium
SodiumNH4
+
4 MEA 1.05 DEA 1.06 Potassium 4.87 TEA 5.08 MDEA 4.89 Calcium 5.010 Magnesium
0.52 1.03
4.0
1.0
Ion exchangeIon exchange
Chromatography
ppm
CationsCations
ic_theory_20041011_e.ppt 22
IC ICIC IC
IC
Ion exchangeIon exchange
Chromatography
I II IIIIII IVIV VV VIVI VIIVII VIIIVIII II IIII III IV V VI VII VIIIH He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Ku
CationsCations (selected)(selected)
ic_theory_20041011_e.ppt 23
IC ICIC IC
IC
Anion separation mechanismAnion separation mechanismStationary phase and mobile phase compete for the analyte
Ion exchangeIon exchange
Chromatography
ic_theory_20041011_e.ppt 24
IC ICIC IC
IC
A Supp 5 – 250NaHCO3/Na2CO3; 1/3.2 mmol/L1 Fluoride
ChloriteBromate
4 Chloride 5.05 Nitrite 5.07 Chlorate 5.08 Bromide 5.09 Nitrate 5.010 Phosphate 5.011 Sulfate
5.02 5.03
5.0
5.0
Ion exchangeIon exchange
Chromatography
ppm
AnionsAnions
ic_theory_20041011_e.ppt 25
IC ICIC IC
IC
Ion exchangeIon exchange
Chromatography
I II IIIIII IVIV VV VIVI VIIVII VIIIVIII II IIII III IV V VI VII VIIIH He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Ku
Anions (selected)Anions (selected)
ic_theory_20041011_e.ppt 26
IC ICIC IC
IC
CationsCationsCations interact with the basic ion-exchange sites of the stationary phase. According to the strength of binding (ion exchange equilibrium constant) these will be eluted earlier or later by the following protons from the eluent.
Anions Anions Anions interact with the acidic ion-exchange sites of the stationary phase. According to the strength of binding (ion exchange equilibrium constant) these anions will be eluted earlier or later by the following carbonate ions from the eluent
SeparationDifferent ion exchange equlibrium constants lead to different retention times of the respective cations or anions and that means separation of the substances which are «chemically quite similar».
Ion exchangeIon exchange
Chromatography
ic_theory_20041011_e.ppt 27
IC ICIC IC
IC
Ion exclusionIon exclusion
Chromatography
Anion separation mechanismAnion separation mechanismLipophilic interaction between analyte and stationary phase
ic_theory_20041011_e.ppt 28
IC ICIC IC
IC
Metrosep Organic AcidsPerchloric acid; 0.5 mmol/L
1 LactateFormateAcetate
4 Propionate 1.05 Butyrate 1.07 iso-Butyrate 1.08 Valerate 1.09 iso-Valerate
1.02 1.03
1.0
1.0
Ion exclusionIon exclusion
Chromatography
ppm
Organic acidsOrganic acids
ic_theory_20041011_e.ppt 29
IC ICIC IC
IC
Mobile PhaseMobile PhaseAnions are excluded and elute with the void volume in the solvent front. Anions of organic acids form with protons weak organic acids. These acids are only to a small degree dissociated and have a low polarity.
Stationary phaseStationary phaseOn the ion exchanger a Donan membrane is formed. This membrane has a low polarity.
InteractionInteractionAs long as the organic acids are not dissociated they can stay in the Donan membrane. If they are dissociated they become ionic. In this case they are excluded from membrane.
Attention! Attention! Cations will be separated by ion exchange and therefore may disturb the chromatogram.
Ion exclusionIon exclusion
Chromatography
ic_theory_20041011_e.ppt 30
IC ICIC IC
IC
Ion pairIon pair
Chromatography
CationCation and anion separation mechanismand anion separation mechanism«RP» reversed phase mechanism
ic_theory_20041011_e.ppt 31
IC ICIC IC
IC
Mobile PhaseMobile PhaseThe mobile phase is of high polarity (e.g. acetonitrile or methanol/water)
Stationary phaseStationary phaseThe stationary phase (e.g. C18) is of low polarity a type of «RP»-Phase.
CationsCationsAnalyte cation (e.g. Na+) plus lipophilic anion (e.g. alkyl sulphonic acid) form a non polar molecule
AnionsAnionsAnalyte anion (e.g. Cl–) plus lipophilic cation (e.g. tetra butyl ammonium) form a non polar moleculeThe lipophilic end of the modified anion or cation molecule interact with the stationary phase in the «RP»-mode. This interaction leads to different retention times and that means separation of substances which are «chemically quite similar».
Ion pairIon pair
Chromatography
ic_theory_20041011_e.ppt 32
IC ICIC IC
IC
Eluent Pump Injector Column Detector
DetectionDetection
Chromatography
ic_theory_20041011_e.ppt 33
IC ICIC IC
IC
Conductivity detectorAmperometric detectorUV/VIS detector (optical)RI detector (optical)IC/MS
Types of detectionTypes of detection
DetectionDetection
Chromatography
ic_theory_20041011_e.ppt 34
IC ICIC IC
IC
Measuring principleMeasuring principleA defined decent potential is applied to a three electrode system consisting of reference-, working- and auxiliary-electrode. If any oxidizable substance pass these electrodes an oxidation process takes place. A current corresponding to the concentration of the respective substance is measured.
ElectrochemicalElectrochemical
Detection
Simple connection to any IC- or HPLC-systemLarge variety of electrode materials (glassy carbon, carbon paste, silver, gold, etc.)Highly sensitiveVery selectiveExcellent price/performance ratio
ic_theory_20041011_e.ppt 35
IC ICIC IC
IC
CharacteristicsCharacteristicsSensitive to UV-active ions e.g. nitrite, nitrate, thiosulfateAlmost no interference by non-chromophoric ions e.g. chloride, sulphateEluent must be UV-transparentLimited possibilities of organic modifiers
UV/VISUV/VIS
Detection
ic_theory_20041011_e.ppt 36
IC ICIC IC
IC
CharacteristicsCharacteristicsUV-adsorbing eluent e.g. phthalic acidsAll ions with no adsorbance at the UV-wavelength applied aredetectedDetector must be extremely sensitive because measurements are performed with very low light intensitySensitivity is lower than the sensitivity achieved by conductivity detection
UV/VIS indirectUV/VIS indirect
Detection
ic_theory_20041011_e.ppt 37
IC ICIC IC
IC
CharacteristicsCharacteristicsSelective determinationsTime consuming (wet chemistry is needed)More complex systemAdditional peak broadeningLast possibility if all other approaches fail
UV/VIS with UV/VIS with pcrpcr
Detection
ic_theory_20041011_e.ppt 38
IC ICIC IC
IC
CharacteristicsCharacteristicsQualitative and quantitative informationDetermination of single atomsDetermination of molecule fragmentsExpensive set upHigh operating costs
IC/MSIC/MS
Detection
++ ++++++ + ++ ++
Quadrupole
LensesFragmentation zone (CID)
IC outlet
SkimmersCapilla
ryOctopo
le Detector
ic_theory_20041011_e.ppt 39
IC ICIC IC
IC
What is What is conductometryconductometry??Conductometry is the measurement of conductivity – a conductometricdetector measures the electrical conductivity of ions in a solution. This is done by applying an electrical field between two electrodes. The ions migrate in this field. The anions migrate to the anode and the cations to the cathode. The electrical resistance of the solution is measured. The conductivity is the reciprocal of the resistance. Alternating current is used in order to avoid substance changes and the formation of diffusion boundary layers at the electrodes.
κ =1R cK*
R = resistance [Ω]
Kc = cell constant [1/cm]
κ = specific conductivity [1/ Ω or S]
ConductivityConductivity
Detection
ic_theory_20041011_e.ppt 40
IC ICIC IC
IC
What is specific conductivity?What is specific conductivity?The specific conductivity κ of an eluting ion depends on the concentration c of the individual ions i, the charge Zi, and the equivalent conductivity Λi. The equivalent conductivity Λi is a concentration-dependent quantity. The values listed can be applied for concentrations below 0.001 mol/L. Zi is the charge of the respective ion.
Λi = equivalent conductivity [S∗cm2/mol]zi = charge [ ]ci = concentration [mol/L] κ = specific conductivity [1/ Ω or S]Σ = sum of all ions – anions and cations
κ = ∑ ( * * )Λ i i iz c
ConductivityConductivity
Detection
ic_theory_20041011_e.ppt 41
IC ICIC IC
IC
Values for equivalent conductivityValues for equivalent conductivityAnions
OH– 198F– 54Cl– 76Br– 78I– 77NO2
– 72NO3
– 71HCO3
– 45½CO3
2– 72½SO4
2– 80½Phthalate 38
CationsH+ 350Li+ 39Na+ 50K+ 74NH4
+ 73½Mg2+ 53½Ca2+ 60Sr2+ 59½Ba2+ 64½Zn2+ 53½Cu2+ 55
ConductivityConductivity
Detection
[c] < 0.001 mol/L; Λ∝ = equivalent conductivity [S∗cm2/mol]
ic_theory_20041011_e.ppt 42
IC ICIC IC
IC
What influences the measured value?What influences the measured value?
κ = ∑ ( * * )Λ i i iz cκ =
1R cK*
the equivalent conductivity of the respective ions
the charge of the respective ions
the cell constant ⇒ ⇒⇒ which are constant
the temperature ⇒ ⇒ ⇒ which should be constant
the concentration ⇒ ⇒ ⇒ which is the actual result
Λ ≈ T ≈ 2 %/°CκEl El El El Elc c. . . . .* *= ++ + − −Λ Λ
ConductivityConductivity
Detection
ic_theory_20041011_e.ppt 43
IC ICIC IC
IC
Ion chromatography without suppression
Ion chromatography with suppression
With or without?With or without?
Chemical suppression
ic_theory_20041011_e.ppt 44
IC ICIC IC
IC
CharacteristicsCharacteristics• Background conductivity = eluent• Conductivity in a peak = eluent plus sample• Measured value = difference between eluent plus sample and
background
κ κ κDet Peak El. .= − κDet Smpl Smpl El Smpl Smpl Elc c. . . . . . .*( ) *( )= − + −+ + + − − −Λ Λ Λ Λ
WithoutWithout
Chemical suppression
ic_theory_20041011_e.ppt 45
IC ICIC IC
IC
45
Determination of Determination of cationscations and anionsand anions
Keywords:one column technique – non suppressed ion chromatography –measurement of the difference between the conductivity of thesample ion and the eluent ion
κDet Smpl Smpl El Smpl Smpl Elc c. . . . . . .*( ) *( )= − + −+ + + − − −Λ Λ Λ Λ
κDet Smpl Smpl Elc. . . .* ( )= −− − −Λ ΛκDet Smpl Smpl Elc. . . .* ( )= −+ + +Λ Λ
The counter ion of the sample is not retained and eluted in the void volume so the counter ion is always that of the eluent
WithoutWithout
Chemical suppression
ic_theory_20041011_e.ppt 46
IC ICIC IC
IC
46
Ion chromatography with chemical suppressionIon chromatography with chemical suppression
In cation chromatography an anion exchanger is used– all anions are replaced by OH–
in anion chromatography a cation exchanger is used– all cations are replaced by H+
By this reaction an eluent with high conductivity is trans-ferred to water (+ CO2↑) which is of low conductivity.
Suppression reduces the background conductivity.
Suppression changes the counter ions in the sample.
WithWith
Chemical suppression
ic_theory_20041011_e.ppt 47
IC ICIC IC
IC
47
CharacteristicsCharacteristicsBackground conductivity = water = zeroConductivity in a peak = water plus sampleMeasured value = difference between water + sample and background
κ κ κDet Peak El. .= −
κDet Smpl Smpl El Smpl Smpl Elc c. . . . . . .* ( ) *( )= − + −+ + + − − −Λ Λ Λ Λ
WithWith
Chemical suppression
ic_theory_20041011_e.ppt 48
IC ICIC IC
IC
Determination of Determination of cationscations and anionsand anions
Keywords:two column technique – suppressed ion chromatography – pcrmeasurement of the sum of the sample ion and H+ or OH–
κDet Smpl Smpl El Smpl Smpl Elc c. . . . . . .* ( ) *( )= − + −+ + + − − −Λ Λ Λ Λ
κDet Smpl Smpl Hc. . . .* ( )= +− +Λ ΛκDet Smpl Smpl OHc. . . .*( )= ++ −Λ Λ
Eluent conductivity is zero andthe counter ion is always OH– or H+
WithWith
Chemical suppression
ic_theory_20041011_e.ppt 49
IC ICIC IC
IC
(Sample = NaCl – Eluent = HNO3)
κDet Smpl Smpl OHc. . .* ( )= ++ −−Λ Λκ Det Smpl Smpl Elc. . . .* ( )= −+ +Λ Λ
κ Det Smpl Na Hc. . * ( )= −+ +
+ +Λ Λκ D e t S m p lc. . * (5 0 )= − 3 5 0
300*.. −= SmplDet cκ
IC without suppression IC without suppression –– Cations Cations –– IC with suppressionIC with suppression
(Sample = NaCl – Eluent = HNO3)
κDet Smpl Na OHc. . * ( )= ++ −
+ −Λ Λκ D et S m p lc. . * (5 0 )= + 1 9 8
κ D e t S m p lc. . *= 2 4 8
ComparisonComparison
Chemical suppression
ic_theory_20041011_e.ppt 50
IC ICIC IC
IC
(Sample = NaCl – Eluent = NaOH) (Sample = NaCl – Eluent = NaOH)
κ Det Smpl Smpl Elc. . . .* ( )= −− −Λ Λκ Det Smpl H Clc. . * ( )= ++ −
+ −Λ Λ)(* ... ΛΛ −−−− −= OHClSmplDet cκ
)19876(*.. −= SmplDet cκ
112*.. −= −SmplDet cκ
κ D et Sm plc. . * ( )= +350 76
κDet Smpl H Smplc. . .* ( )= ++
+ −Λ Λ
κ D e t S m p lc. . *= 4 2 6
IC without suppression IC without suppression –– Anions Anions –– IC with suppressionIC with suppression
ComparisonComparison
Chemical suppression
ic_theory_20041011_e.ppt 51
IC ICIC IC
IC
ComparisonComparison
Chemical suppression
ic_theory_20041011_e.ppt 52
IC ICIC IC
IC
high background conductivityanions with low sensitivitycations with high sensitivityhigh linearity in calibrationlow cost set upfreedom of choice for eluents
low background conductivityanions with high sensitivity(detection limits 2-4 x lower)cations with high sensitivitynon linear calibrationmore expensive set upeluents must react to H2O
ComparisonComparisonIC without suppression IC with suppressioIC without suppression IC with suppressionn
Chemical suppression
ic_theory_20041011_e.ppt 53
IC ICIC IC
IC
Housing
Anode
Cathode[H2SO4]
Ion exchangemembranes
H+ ↓
OH–↑
OH–↑OH–↑
OH–↑
OH–↑
H+ ↓+ Na+ ↓
Na+ ↓Na+ ↓
OH–↑OH–↑
–
H2O ↓ Eluent/Sample ↓ ↑ H2O
H2 + O2
↑ Eluent/Sample
2 OH– – 4 e– → O2 + 2 H+
H2O → H+ + OH–
2 H+ + 2 e– → H2
Na+ → H+
Cl– → OH–
ASRSASRS
Suppressors
«Auto self regenerating suppressor» for anions or cations
ic_theory_20041011_e.ppt 54
IC ICIC IC
IC
Membrane SuppressorMembrane SuppressorContinuous regenerationNo additional solventsNot solvent stableExpensiveLimited lifetimeNoise 3-5 nS
EvaluationEvaluation
Suppressors
ic_theory_20041011_e.ppt 55
IC ICIC IC
IC
Metrohm Suppressor Module «MSM»Metrohm Suppressor Module «MSM»
Suppressors
Na+ → H+ / Na2CO3 → H2CO3
Me+ → H+ / MeCl → H+ + Cl–
← H2SO4
Regeneration
Rinsing← H2O
Suppression
Packed bed suppressorPacked bed suppressor
ic_theory_20041011_e.ppt 56
IC ICIC IC
IC
Metrohm Suppressor Module «MSM»Metrohm Suppressor Module «MSM»Regeneration outside the analytical lineRegeneration with organic solvents (e.g. 25 % acetone) possibleRegeneration with strong acids possibleBack pressure stability 2 MPa without effecting the analytical runUnlimited pressure stability without being destroyedLong lifetime and though inexpensiveLow noise 0.2-0.5 nS
EvaluationEvaluation
Suppressors
ic_theory_20041011_e.ppt 57
IC ICIC IC
IC
Suppressors
H2CO3 → H2O + CO2
From «MSM»
CO2 →
Removal
Outlet↓ H2O
Sequential suppressionSequential suppression
Metrohm COMetrohm CO22 Suppressor «MCS»Suppressor «MCS»
ic_theory_20041011_e.ppt 58
IC ICIC IC
IC
EvaluationEvaluation
Suppressors
Metrohm COMetrohm CO22 Suppresser «MCM»Suppresser «MCM»separation advantages of the carbonate / bicarbonate eluent system in combination with the low background of a hydroxide eluentlower detection limits because of greater peak areasLOD 0.7 – 1.9 ppb with 20 µL injection volume using the Metrohm 761 Compact ICno increase of chemical and/or electronic noisegradient capabilitiessignificantly reduced carbonate influenceeasy upgrade of existing systems
ic_theory_20041011_e.ppt 59
IC ICIC IC
IC
Ion ChromatographyIon ChromatographyPrinciples of chromatography Chromatographic separation techniquesIon chromatography separation techniquesDetection in ion chromatographyConductivity measurementsSuppression reactionConductivity after suppression reaction
ResumeResume
What is IC?