Liquid chromatography

Chromatography using liquid as mobile phase

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

liquid phase Chromatography Is to use liquid as mobile phase Chromatographic method of. 1906 Russian botanist Tswett (M.S.Tswett) Add the plant pigment extract to the upper part of the glass column with calcium carbonate particles, and then wash the column with petroleum ether. As a result, different pigments are separated in the column to form different color bands. Each band represents different pigments. Since then, these methods are called chromatography. With the development of chromatography technology, chromatography can not only be used to separate colored substances, but also widely used to separate colorless substances, especially organic compounds.

Chinese name: Liquid chromatography

Foreign name: Liquid chromatography
Pinyin: yè xiàng sè pǔ fǎ

catalog

▪ Gel permeation chromatography
▪ Ion chromatography
▪ Ion pair chromatography
three Application of liquid chromatography

Liquid chromatography

Announce

edit

Liquid chromatography

liquid phase chromatographic Cannot be controlled by Chromatogram The qualitative results of unknown objects must be given directly, and must be qualitatively compared with known standards. When there is no control of pure substances, qualitative identification is very difficult. At this time, mass spectrometry, infrared and chemical methods are needed. Most other metals salt and thermal stability Poor substances cannot be analyzed yet. This disadvantage can High performance liquid chromatography To overcome.

Principle and classification

Announce

edit

liquid phase chromatographic The separation mechanism of the method is based on the difference of affinity and force between the two components in the mixture. According to the different stationary phases, liquid chromatography can be divided into liquid-solid chromatography, liquid-liquid chromatography and bonded phase chromatography. Liquid solid chromatography with silica gel as filler and bonded phase chromatography with micro silica gel as matrix are most widely used. According to the form of stationary phase, liquid phase Chromatography It can be divided into Column chromatography 、 Paper chromatography and Thin layer chromatography 。 It can be divided into adsorption chromatography Distribution chromatography 、 Ion exchange chromatography and Gel permeation chromatography 。 In recent years, high pressure liquid flow system has been added to the liquid column chromatography system, so that mobile phase It flows rapidly under high pressure to improve the separation effect, so high performance (also called high pressure) liquid chromatography has emerged^[1] 。

Liquid-solid adsorption chromatography

High performance liquid chromatography One of them is based on substance Adsorption To achieve separation. Its stationary phase is some substances with adsorption activity, such as silica gel alumina 、 molecular sieve , polyamide, etc.

Liquid-liquid partition chromatography

Based on the measured substance in the stationary phase and mobile phase The difference in relative solubility between solute Distribute between the two phases to achieve separation. According to the Polarity Different, divided into normal phase chromatographic and Reverse phase chromatography 。 The former uses silica gel or polar bonding phase as the stationary phase Polar solvent Is mobile phase; The latter is the alkyl bonded phase with silica gel as the matrix as the stationary phase, and the polar solvent as the mobile phase, which is suitable for the separation of non-polar compounds.

Ion exchange chromatography

Based on ionizable ions on ion exchange resin and mobile phase With the same charge solute Reversible exchange of ions according to these ion pair Ion exchange The radical has different affinity to achieve separation. Thin shell type ion exchange resin Column efficiency High, mainly used to separate simple mixtures; Porous resin has a large sample injection capacity and is mainly used to separate complex mixtures.

Gel permeation chromatography

Also called size exclusion Chromatography 。 It was first used in biochemistry in 1959. As solvent mobile phase , porous filler (such as porous silica gel Porous glass ）Or porous Cross-linked polymer Gel: Set & Match For separating media liquid phase Chromatography. When the mixture solution enters the gel chromatographic column When flowing through the porous gel, the molecules with larger volume than the pores of the porous gel cannot penetrate into the pores of the gel, but flow through the gaps of the gel particles, and are washed out of the column earlier Small molecule It can penetrate into the gel pores and be washed out later. After passing through the gel chromatographic column, the mixture flows out of the column successively according to its molecular size to achieve the purpose of separation. use Gel permeation chromatography The utility model has the advantages that: gradient flushing device is not required for separation; A column of the same size can accept a much larger sample volume than the usual liquid chromatography; The sample is less diluted in the column, so it is easy to detect; Compositional retention time It can provide molecular size information; chromatographic column Long life. Its disadvantages are: it cannot separate mixtures with the same molecular size, and the resolution of the chromatographic column is low; Peak capacity Small; Other retention mechanisms may cause interference. Gel permeation chromatography is used to determine Molecular weight of high polymer and molecular weight distribution It provides an effective method and can also be used to separate Oligomer , monomer and polymer Additives, etc.

Ion chromatography

Adopt column chromatographic One kind of technology High performance liquid chromatography The sample is developed by elution method. According to different separation methods, Ion chromatography It can be divided into high performance ion chromatography, ion exclusion chromatography and Mobile phase ion chromatography Category 3. Efficient Ion chromatography Use low capacity ion exchange resin ， Separation mechanism Mainly Ion exchange 。 Ion exclusion chromatography With high capacity resin, the separation mechanism is mainly based on the principle of ion exclusion. Mobile phase ion chromatography uses porous resin without ion exchange groups. The separation mechanism is mainly based on adsorption and ion pair Formation of.

The ion chromatograph consists of eluent reservoir, pump, injection valve, separation column, suppression column, conductivity detector and data processing unit. The most important component of the ion chromatograph is the separation column, which is equipped with ion exchange resin 。 The suppression column is used for suppression ion chromatograph Key components Its function is to transform the eluent into a part with low conductivity, so as to reduce the background conductivity from the eluent, and transform the sample ions into their corresponding acids or bases, so as to increase their conductivity. separate anion , suppress column fill Strongly acidic cation exchange resin ； Separation of cations, suppression column filling Strongly basic anion exchange resin 。 detector There are general detectors and special detectors. The former, such as conductivity detector, responds to all ions in the detection cell; The latter is as follows Ultraviolet visible spectrophotometer , has selectivity Response.

Ion pair chromatography

ion pair Chromatography It refers to one (or several) ion (B -) opposite to the sample ion charge (A+), which is called pair ion or Counterion , Counterion) chromatographic Systematic mobile phase (or stationary phase), so that it can combine with the sample ion to form a weak polar ion pair (neutral association ）。 This ion pair is not easy to be in water dissociation And quickly enter the organic phase to control solute Ion retention behavior.

Application of liquid chromatography

Announce

edit

advantage

Ion chromatography It has the advantages of rapidity, sensitivity, selectivity and simultaneous determination of multi-component. Especially for the determination of anions, Ion chromatography It is a breakthrough in analytical chemistry.

application

Ion chromatography It is mainly used to determine the content of various ions, and is widely used in water pulp and Bleach , food analysis, biological fluid, steel, environmental analysis and other fields.

equipment

Announce

edit

High performance liquid chromatography By output pump, sample injection device chromatographic column Gradient washing device, detector, data processing and microcomputer control unit form. The function of the output pump is to Rinsing agent The mixture sample is continuously fed into the column system under high pressure, so that chromatographic Complete the separation process in^[2] 。 There are three common injection methods: syringe diaphragm injection Valve injection and Autosampler Injection. The function of the chromatographic column is to separate the components in the mixture. Gradient washing, also known as solvent procedure, improves the resolution of complex samples, shortens the analysis cycle and improves the peak shape by continuously changing the composition of washing agent. Its function is similar to Gas chromatography In Temperature programmed 。 The function of the detector is to display or convert the separated components from the chromatographic column into corresponding electrical signals, mainly including UV absorption detector 、 Fluorescence detector 、 Electrochemical detector And refractive index differential detector, of which ultraviolet absorption detector is the most widely used^[3] 。 Modern instruments are equipped with computers to automatically process data, plot and print analysis reports.

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001