Ion chromatography columnTechnology is an important technical indicator that characterizes the technical strength of ion chromatography instrument manufacturers.

Domestic ion chromatography columnIntroduction:

The determination of ionic compounds in solution is the main content of classical analytical chemistry. There are already some fast and sensitive analysis methods for cations, such as atomic absorption, high-frequency inductively coupled plasma emission spectroscopy, and X-ray fluorescence analysis. However, there has been a lack of fast and sensitive methods for the analysis of anions for a long time, and classical volumetric, gravimetric, and photometric methods have been used. These methods are mostly time-consuming and require multiple chemical reagents, with low sensitivity and interference. Ion chromatography has the advantages of being fast, sensitive, selective, and capable of simultaneously determining multiple components, many of which are currently difficult to determine by other methods, especially anions. The analysis of anions by ion chromatography is a new breakthrough in analytical chemistry. If high-frequency inductively coupled plasma emission spectrometry (ICP-MS) is currently the fast, sensitive, and accurate analytical method for simultaneously measuring multiple elements, then the fast, sensitive, and accurate analytical method for simultaneously measuring multiple anions is ion chromatography.

characteristic:
1. Fast and convenient
In modern society, the time required to complete an analytical task is becoming increasingly important. Regarding 7 common anions (F^-、 Cl^-、 Br^-、 NO₂^-、 NO₃^-、 SO₄^2-、 PO₄^3-And six common cations (Li) 、 Na 、 NH4 、 K 、 Mg² 、 Ca² ）The average analysis time has been less than 10 minutes. The separation of the seven most important common anions mentioned above using an efficient and rapid separation column only takes 3 minutes.
Easy to use is one of the hallmarks of contemporary IC development. Some of the problems that users find troublesome have been well resolved. NaOH is the recommended eluent for analyzing anions in chemically inhibited IC, as its inhibitory reaction product is low conductivity water. But during preparation and use, CO in the air₂Will always dissolve into NaOH solution and generate CO₃^2-, causing baseline drift and sometimes ghost peaks. The online rinsing solution generator based on the principle of electrolysis avoids contact between the rinsing solution and air, and can obtain the required accurate concentration of pollution-free KOH rinsing solution with only the mouse on the workstation. Another example is the electrochemical membrane suppressor, which does not require regeneration and can work continuously.

2. High sensitivity
The concentration range for ion chromatography analysis is μ g/L-mg/L. Directly injecting 50 μ l, the detection limit for common anions is less than 10 μ g/L. For high-purity water used in power plants, nuclear power plants, and semiconductor industries, the detection limit can reach 10% by increasing the injection volume, using small hole diameter columns (2mm diameter) or online concentration methods^-12G/L or lower. The improvement of detection sensitivity is often related to the improvement of selectivity, such as the combination of IC and inductively coupled plasma mass spectrometry (ICP-MS): the detection limits for arsenic, lead, tin, mercury, chromium, lanthanide elements, phosphorus, sulfur, vanadium, and nickel are 20, 0.2, 2, 7, 20, 1400, 700, 0110, and 30pg, respectively₃^-, BrO₃^-， Cl^-， ClO^₃-, Br^-And I^-The detection limits are 25ng iodine, 0.8ng bromine, and 36ng chlorine, respectively.
Compared with ICP-MS method, post column derivatization reaction is a low-cost and simple method to improve detection sensitivity.

3. Good selectivity
The selectivity of IC method for analyzing inorganic and organic cations and anions is mainly achieved by selecting appropriate separation and detection systems. Compared with HPLC, the effect of relative selectivity in IC fixation is greater. Although there are dozens of highly efficient separation columns with different selectivity available in the market, research on stationary phases has always been a hot topic in IC, and new separation columns are introduced every year in Pittsburgh. When using a conductivity detector, suppression techniques are important because they may be counter ions of the tested ions (such as Cl in NaCl) that interfere with the source^-When, Na For counterions, measure NH₄NO₃In NH₄ When, NO₃^-In the inhibition reaction, they will react separately with H as counter ions Or OH^-Exchange, enter the waste liquid. Selecting solute characteristic detectors to improve the selectivity of certain complex sample analyses, such as Cl^-No UV absorption,
And NO₃^-And NO^₂-Strong UV absorption, using UV visible detector can easily detect high Cl^-The NO in₂^-And NO₃^-The development of post column derivatization methods has improved the detection selectivity for metal ions, multivalent anions, and sulfates. Due to the selectivity of IC, the requirements for sample pretreatment are simple, usually only for dilution and filtration.

4. Can simultaneously analyze multiple ionic compounds
Compared with photometry and atomic absorption spectroscopy, the main advantage of IC is the simultaneous detection of multiple components in the sample. All information about anions, cations, and sample composition can be obtained in a short amount of time. But the ability to detect simultaneously is limited by the huge concentration differences between different components in the sample. For example, it is difficult to simultaneously detect high and low concentration components in wastewater samples. For the analysis of such samples, different sensitivity settings or dilution levels are commonly used for two or more injections. The successful development of efficient and high-capacity columns in the 1990s effectively solved some of the above problems, such as Dionex's IonPac CS15 cation separation column, which added crown ethers with an inner diameter of 1.38nm to its resin modification groups, which improved K The reservation is strong for K With NH₄ Or Na give
NH₄ Samples with a concentration ratio of up to 10000:1 can still be injected without pre-treatment and tested simultaneously.

5. The separation column has good stability and high capacity
The stability of the separation column depends on the type of column packing. Unlike the silica gel fillers used in HPLC, styrene/divinylbenzene polymers are the most widely used fillers in IC. The high pH stability of this resin allows for the use of strong acids or bases as eluents, which is beneficial for expanding its application range. The new high crosslinking resin is stable in organic solvents. Therefore, organic solvents can be used to clean the column to remove organic pollutants. High pH stability, organic solvent compatibility, and high column capacity simplify sample pretreatment procedures. Dissolution, dilution, and filtration are the main contents of sample pretreatment in IC.