Ion chromatography is a kind of high performance liquid chromatography, so it is also called high performance ion chromatography (HPIC) or modern ion chromatography. It is different from traditional ion exchange column chromatography mainly because the resin has a high degree of crosslinking and a low The exchange capacity is small, the injection volume is small, and the eluent is usually delivered by a plunger pump to perform online automatic continuous conductivity detection.
Ion chromatography (IC), is an analytical technique used to identify the molecular make-up of materials. Ion chromatography has become an important analytical methodology in pharmaceuticals, environmental quality analysis, and industrial inorganic and organic contaminant analysis. HPIC (High Performance Ion Chromatography) offers efficient way of contaminant analysis. It offers the environmental, industrial, biological, pharmaceutical, chemical and food sectors a simple, fast and accurate materials analysis technique with applications that range from quality control to environmental analysis.
How ion chromatography works
The principle of separation is based on the reversible exchange between the dissociable ions on the ion exchange resin and the solute ions with the same charge in the mobile phase and the difference in the affinity of the analyte solute for the exchanger. It is suitable for the separation of hydrophilic anions and cations.
For example, for the separation of several anions, after the sample solution is injected, ion exchange is first performed directly with the ion exchange position of the analytical column (that is, it is retained on the column), such as using NaOH as the eluent to analyze F-, Cl- and SO42-, the anions retained on the column are replaced by OH- groups in the eluent and eluted from the column. Analyte ions with weak affinity for resin are eluted in sequence before those with strong affinity for resin. This is the ion chromatography separation process. The eluate passes through a chemical suppressor to minimize the background conductance from the eluent. This results in a larger conductance signal that can be accurately measured as the analyte leaves the cell.
The basic structure of ion chromatography
Like general HP LC instruments, ion chromatographs are generally made into unit components first, and then the required unit components are combined according to the analysis requirements. The most basic components are the mobile phase container, high pressure infusion pump, injector, chromatographic column, detector and data processing system. In addition, mobile phase online degassing device, automatic sampling system, mobile phase suppression system, post-column reaction system and fully automatic control system can be configured as required.
The working process of the ion chromatograph is: the infusion pump delivers the mobile phase to the analysis system at a stable flow rate (or pressure), the sample is introduced through the injector before the chromatographic column, and the mobile phase brings the sample into the chromatographic column. The components are separated and flow to the detector with the mobile phase in turn. In the suppression type ion chromatography, a suppression system is added before the conductivity detector, that is, another high-pressure infusion pump is used to transport the regeneration liquid to the suppressor, and the suppressor In the process, the background conductance of the mobile phase is reduced, the effluent is then directed into a conductance detection cell, and the detected signal is sent to a data system for recording, processing, or storage. The non-suppressed ion chromatograph does not need a suppressor and a high-pressure pump for delivering regeneration fluid, so the structure of the instrument is relatively simple and the price is much cheaper.
Ion Chromatography Workflow
Approximate process: The high-pressure infusion pump delivers the mobile phase to the analysis system at a stable flow rate (or pressure), and the sample is introduced through the injector before the chromatographic column, and the mobile phase brings the sample into the chromatographic column. are separated, and in turn flow to the detector with the mobile phase. Suppressed ion chromatography adds a suppression system before the conductivity detector, that is, another high-pressure infusion pump is used to deliver the regenerant to the suppressor. In the suppressor, the background conductance of the mobile phase is reduced, the effluent is then directed into a conductivity cell, and the detected signal is sent to a data processing system for recording, processing, or storage. The non-suppressed ion chromatograph does not need a suppressor and a high-pressure pump for conveying the regeneration liquid, so the structure of the instrument is relatively simple and the price is relatively cheap.
Uses of Ion Chromatography
Ion chromatography is mainly used for the analysis of environmental samples, including anions and cations in samples such as surface water, drinking water, rainwater, domestic sewage and industrial wastewater, acid sediments and atmospheric particles, and traces in water and reagents related to the microelectronics industry Analysis of quantitative impurities.
In addition, it is also widely used in the fields of food, health, petrochemical, water and geology.
Common ions that are often detected are
Anions: F-, Cl-, Br-, NO2-, PO43-, NO3-, SO42-, formic acid, acetic acid, oxalic acid, etc.
Cations: Li+, Na+, NH4+, K+, Ca2+, Mg2+, Cu2+, Zn2+, Fe2+, Fe3+, etc.
Ion chromatograph is its specialty in the separation and determination of common anions. Once a sample is injected, the determination results of 7 common ions can be obtained within about 20 minutes, which cannot be achieved by other analytical methods. Chromatography did not show superiority compared to AAS and ICP.
Environment: Atmospheric composition (dust, particulate matter, mist, acid gas), acid rain, water quality analysis
Food: Contaminated ingredients, additives, inherent ingredients, adulteration, production process monitoring
Agriculture: Pesticides, Fertilizers, Soil, Feed, Grain, Plant Analysis
Medicine: blood, urine, infusion components, clinical examination, human body trace element analysis
Biological: protein separation and purification,
Pharmaceuticals: Analysis of botanical medicinal materials, mineral medicinal ingredients and preparation ingredients
Materials: metal materials, semiconductor materials, surface treatment, ultrapure water analysis
Industry: raw material analysis, product quality control, electrolytic plating solution analysis, papermaking
Chemical: raw material and product analysis, reaction process monitoring
Daily Chemicals: Analysis of Cosmetics, Detergents, Cleaners, Raw Materials and Product Composition
Classification of ion chromatography
1. Ion chromatography separation
Ion chromatography separation is mainly based on the principle of ion exchange, and ion exchange resin with low exchange capacity is used to separate ions. It is the most widely used in ion chromatography, and its main filler type is organic ion exchange resin.
2. Ion pair chromatography
The stationary phase of ion-pair chromatography is a hydrophobic neutral filler, and the counterion used for anion separation is alkylamines, such as tetrabutylammonium hydroxide, hexadecyltrimethane hydroxide, etc. The counter ions used for cation separation are alkyl sulfonic acids, such as sodium hexane sulfonate, sodium heptane sulfonate, and the like.
3. Ion exclusion chromatography
Ion exclusion chromatography is mainly based on the Donnon membrane exclusion effect: ionized components are rejected and not preserved, while weak acids are made on the principle of certain preservation. Ion exclusion chromatography is mainly used to separate organic acids and inorganic oxygen-containing acid radicals, such as borates, carbonates and sulfates, organic acids, etc.
4. The application of ion chromatography
Detection of inorganic anions; detection of inorganic cations and analysis of organic anions and cations, mainly including analysis of biogenic amines, organic acids and sugars.
HPIC Capacity at AxisPharm
Trace ionic species such as F-, Br-, Cl-, NO2-, NO3-, HPO4-2, SO4-2
Trace cation Species such as Li+, Na+, K+, Mg+2, Ca+2, Sr+2, Ba+
Ammonium and low molecular weight amines
Quaternary ammonium compounds
Weak organic acids
Aliphatic and aromatic sulfonic acids
Custom HPIC analysis
Contact one of our highly skilled analysts to discuss your IC analysis needs.
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