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What is Ion Chromatography
Ion chromatography (IC) is a form of liquid chromatography that describes efficient peak separation amongst ionic species.
Used to separate and quantify at trace levels:
Ions/ ionizable molecules
Low-molecular-mass acids and bases
Inorganic anions and cations
Applicable to:
Food analysis
Water quality treatment
Pharmaceuticals
Types of Ion
Chromatography
Ion-exchange Chromatography (IEC)
Ion-exclusion Chromatography (IEC)
Ion-pair Chromatography (IPC)
Ion-suppression Chromatography (ISC)
Ion-exchange
Chromatography (IEC)
Separates inorganic anions and cations
Based on affinity of analyte and charged, ionic R-
groups on stationary phase
Anion & Cation exchangers:
Anion: contain + charged R- groups to attract anions
Cation: contains – charged R- groups to attract cations
Stationary phase composition:
Resins (small molecules)
Gels (macromolecules)
Inorganic exchangers (extreme chemical conditions)
Ion-exclusion
Chromatography (IEC)
Separates weak acids/
bases and hydrophilic
biomolecules (e.g.,
carbohydrates)
Molecular species rather
than ions but can be used
to separate analytes
based on size, shape, and
charge
Functions by Donnan
Exclusion mechanism
http://www.chromacademy.com/lms/sco111/theory_of_hplc_ion-chromatography.pdf
Ion-pair Chromatography
(IPC)
Separates polar and ionic compounds with reversed
phase HPLC column rather than IEC column
Relies heavily on composition of mobile phase for
separation
Organic solvent & ion-pair reagent
Large ionic molecule: w/ charge opposite that of analyte &
hydrophobic region to interact with st. phase (PS/DVB)
Ion-pair Chromatography
(IPC)
To separate cations:
anionic surfactant added
to mobile phase
Lodges into st. phase
ion exchanger
Analyte cations attracted
to surfactant anions
Ion-suppression
Chromatography (ISC)
Separates weak, polar acids and bases
Involves removal of unwanted analyte prior to detection
Anion suppression:
Anions separated using anion separator column and strong base
(eluent)
Passed through suppressor where strong base water
Cation suppression:
Cations separated using cation separator column and strong acid
(eluent)
Passed through suppressor where strong acid water
Sample Preparation
Dependent upon sample composition
Matrix dominated samples:
Matrix elimination IC
SPE
Water samples:
Filtering alone or dilution (to detectable range) and then
filtering
Solid samples:
Aqueous extraction
Acid digestion
Combustion
Analysis Time
Range of 6 to 20 minutes based on research
6.5 minutes: anionic/ cationic nutrients in waste water
samples
7 minutes: arsenic in cereal based foods
10 minutes: anions in lake water samples
12 minutes: transition metals in sea water samples
18 minutes: weak acid determination (food chemistry)
20 minutes: separation of proteins from complex
biological mixtures
How Much Does it Cost?
Thermo Scientific HPIC
system designed to
maximize resolution,
speed, and sensitivity
Approximately $35,000
http://www.thermoscientific.com/content/dam/tfs/ATG/CMD/CMD%
20Product%20Images/Chromatography/Ion%20Chromatography/I
C%20and%20RFIC%20Accessories/ICS-5000-
stacked_Front.tif/jcr:content/renditions/cq5dam.thumbnail.250.250.
png
Operational Theory of IC
Contains: eluent, pump, injection valve, column,
suppressor, detector, data collection system
http://www.shodex.com/assets/images/en-illust/i0055a.gif
Application: Perchlorate
Determination (2013)
Perchlorate: common ingredient in rocket fuel
Causes interference of iodide uptake and proper
functions of thyroid gland serious human health
threat
Contaminating drinking water
Ion exchange chromatography with anion exchange
column
Complete separation of all analytes in sample
completed in 7 minutes
Valid results in relatively short time with little sample
preparation needed
Advantages and Limitations
Advantages
Sample prep is not
extensive (no need to
correct for matrix effects)
Shorter analysis time for
simpler samples (generally
10-12 minutes)
High selectivity with solute
specific detectors
Detect/analyze multiple
sample components
simultaneously
Small sample volume
Sensitivity on μg/L level
Limitations
Soil, sediment, geological
sample prep is more
extensive
Longer analysis time for
more complex samples
Can’t select specific
compounds for high speed
analysis
Sometimes overlap can
occur in chromatogram
when compounds have
similar separation
characteristics
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Chromacademy. Http://www.Chromacademy.Com/lms/sco111/theory_of_hplc_ion-chromatography.Pdf (accessed oct 15, 2014).
Haddad, p. R.; Doble, P.; & Macka, M. Developments in sample preparation and separation techniques for the determination of inorganic ions by ion chromatography and capillary electrophoresis. Journ. Of chrom. A. 1999, 856, 145-177.
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Karmarkar, s. V. Analysis of wasterwater for anionic and cationic nutrients by ion chromatography in a single run with sequential flow injection analysis. Journ. Of chrom. A. 1999, 850, 303-309.
Llorente-mirandes, t.; Calderon, J.; Centrich, F.; Rubio, R.; & Lopez-sanchez, J. F. A need for determination of arsenic species at low levels in cereal-based food and infant cereals. Validation of a method by IC-ICPMS. Food chem. 2014, 147, 377-385.
Gajdoski, m. S.; Kovac, S.; Malatesti, N.; Muller, E.; & Josic, D. Ion-exchange sample displacement chromatography as a method for fast and simple isolation of low- and high-abundance proteins from complex biological mixtures. Food technol. Biotechnol. 2014, 52(1), 58-63.
Thermo scientific. Http://www.Thermoscientific.Com/en/product/dionex-ics-5000-capillary-hpic-system.Html (accessed oct 27, 2014).
Dionex. Principles and troubleshooting techniques in ion chromatography. Dionex corporation: 2002; document no. 034461.
Jackson, p. E.; Gokhale, S.; Streib, T.; Rohrer, J. S.; & Pohl, C. A. Improved method for the determination of trace perchlorate in ground and drinking waters by ion chromatography. Journ. Of chem. A. 2000, 888, 151-158.
Jiang, s.; Li, Y.; & Sun, B. Determination of trace level perchlorate in antarctic snow and ice by ion chromatography coupled with tandem mass spectrometry using an automated sample on-line preconcentration method. Chin. Chem. Lett. 2013, 24, 311-314.
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