Introduction and use precautions for gas phase polymer pellets
Gas phase polymer pellet
Polymer beads, also known as polymeric porous microspheres, polymer porous microbeads, the stationary phase is mostly styrene or ethyl styrene as a monomer, divinyl benzene as a crosslinking agent The copolymer formed has product specifications of different polarities due to differences in synthesis conditions and added components. The specific surface area of ​​the polymer porous sphere is 100-800 m 2 /g, and the bulk density is 0.2-0.4 g/mL.
The main types of polymer porous pellets are Chromosorb "Hundred" series and Porapak series. The main types of domestic polymer porous pellets are GDX series and 400 series.
The new type of polymeric porous sphere, which has unique advantages, has been widely used in analysis. The analysis example is as follows:
The stationary phase of Figure 1 was Porapak Q with a column length of 2 m, a column temperature of 30 ° C, and a carrier gas H 2 of 55 mL/min, detected by TCD.
The stationary phase of Figure 2 was GDX-203 with a column length of 2 m, a column temperature of 160 ° C, and a carrier gas H 2 of 70 mL/min, detected by TCD.
Main characteristics of gas phase polymer pellets
1. Wide applicability
The porous polymer sphere can be used as a stationary phase or as a chromatographic carrier. It can be used to analyze many kinds of gas samples as well as many kinds of liquid samples. It can be used as a column for preparative chromatography. filler.
2. Good physical and chemical properties
Since the porous particles of the polymer have uniform particle size, regular shape and good mechanical strength, high column efficiency can be obtained; in addition, the polymer porous beads have good corrosion resistance and, therefore, can be used for analyzing corrosive substances. Stationary Phase.
3. Chromatographic peak shape is more symmetrical
Separation and analysis of non-polar and weakly polar compounds (eg hydrocarbons, ethers, ketones), or polar compounds such as water, alcohols, acids, amines, nitriles, etc., when they flow out on the polymeric porous sphere stationary phase, their The peak shape is generally symmetrical.
4. Chromatographic peaks flow out regularly
When the mixture sample is separated and analyzed on the polymeric porous microsphere stationary phase, it basically flows out in the order of molecular weight from small to large, and water generally flows out before the liquid organic matter, and therefore, is particularly suitable for the determination of trace moisture.
5. Leakage rarely occurs
The molecular structure of the polymeric porous microsphere stationary phase has high stability, and substantially no loss occurs when operating in the allowable temperature range, so it is suitable for using a highly sensitive detector, which is extremely advantageous for the analysis of trace impurities.
Gas phase polymer pellets precautions
1. Operating temperature
The maximum use temperature of the polymer porous spheres generally cannot exceed 270 ° C, and the special type can reach 450 ° C, otherwise the polymer will undergo thermal decomposition; the maximum use temperature of various polymer porous beads is shown in Table 2-6.
2. Activation treatment
The activation treatment is required before use, and the carrier gas is removed for about 8 hours under the condition of not exceeding the maximum use temperature to remove the solvent, short-chain molecules and some adsorbed components, and contact with air should be avoided during the activation process.
3. Quantitative correction
In the analysis of polar compounds, the polymer porous beads are permanently adsorbed to certain components. If the content of the components is below 100 ppm, a nonlinear response may occur, so attention should be paid to quantitative correction.
4. Eliminate static electricity
Polymer porous spheres tend to carry static electricity and are prone to wall attachment. Therefore, when preparing such columns, scrub the wall with a suitable solvent (such as acetone) or cool it to 0 °C to ensure that the column is filled evenly. .
Further, in order to increase the selectivity of the column, a suitable fixing solution may be applied to the porous polymer beads.
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