SU787983A1 - Chromatographic column and method of producing it - Google Patents

Description

(S) CHROMATOGRAPHIC COLUMN AND METHOD FOR ITS MANUFACTURE

one

This invention relates to chromatography, more specifically to a device and method for producing chromatographic columns.

The known chromatographic column is a tube with a sorbent l.

However, this column has a low separation efficiency.

A chromatographic column, which is a glass capillary tube, is also known, manufactured by drawing short tubes of larger diameter 2 heated to softening temperature.

Compared to columns filled with a granular carrier, such columns are much more efficient, allowing analysis to be carried out much faster and at lower temperatures, which is especially common in the study of high-boiling compounds.

However, working with known columns suggests the use of very small amounts of the substance for analysis, since the sorption capacity of such columns is insignificant. For example, when analyzing a liquid sample in a column

it is required to enter its volume not exceeding a few hundredths of a micrometer, i.e. a volume that cannot be accurately measured by any

5 of the known dosing devices. Therefore, when attaching a column to the chromatograph evaporator, a special device is used in which the sample of the analyte is divided into two parts, with less

a portion of about 10% is in the column, and a large (about 30%) is discharged to the atmosphere.

The need to use such a device makes it difficult to work with capillary columns and adversely affects the results of quantitative analysis, since it is very difficult to determine with a sufficient degree

20 accuracy of the magnitude of the splitting of the sample n. Entering the column, especially when analyzing a mixture of substances with different volatility.

In addition, the effectiveness of the column

25 increases with decreasing diameter of the capillary, but in the chromatographic works practically no hyperfine (diagonal in hundredths of mm) capillary columns are used, which is connected

30 with their extreme fragility. The purpose of the invention is to improve the accuracy of monitoring the splitting of the flow of the mobile phase and simplify the operation of the column. This goal is achieved by the fact that the inside of the glass capillary is at least one glass capillary of the same length but smaller diameter. At the same time, the cross-sectional area of the intercapillary space is larger than the cross-sectional areas of the capillaries, which are located 3-10 times inside. The column is directly attached to the reference point of the chromatograph sample. Since at a constant inlet pressure the velocity of the mobile phase in the space between the inner surface of the tube-casing and the outer surfaces of the capillaries is many times higher than inside the capillaries, the splitting of the flow occurs directly inside the column. The proposed column is made as follows. A smaller diameter tube was inserted into the original glass tube, using the flow from the above ratio. One of the ends of the finished billet is sealed. The billet is filled with an open end into a device for making glass capillary columns and the column is stretched to form a capillary. when stretching the column. FIG. 1-4 depict {on a scale of 1:65) cross-sections of one and three capillary columns obtained according to the inventive method in a common casing, where: in FIG. 1 is the cross section of a column with one capillary and the ratio of the effective cross-sectional area of the intercapillary space to the cross-sectional area to the pillor 10: 1; in fig. 2 is a cross-section of a column with three capillaries and the ratio of the effective cross-sectional area of the intercapillary space to the number of cross-sections of capillary cross-section 10: 1; FIG. 3 - xlonon cross section with one capillary and the ratio of the cross-sectional area between the capillary space to 1g; the cross-section of the capillary is 3: 1; 4 is a column section with three capillaries and the ratio of the effective cross-sectional area of the intercapillary space to the total cross-sectional area of the capillaries is 3: 1. Examples 1-6 describe chromatograms of a mixture of normal hydrocarbons (octane, nonane, and decane), obtained using the known and proposed columns on a Chrom-41 gas-liquid chromatograph. Example. FIG. 5 shows a chromatogram of a mixture of normal hydrocarbons obtained on a known column 30 m long and 0.6 mm in inner diameter under the following conditions: the pressure of the carrier gas at the inlet is 0.3 atm, the temperature in the thermostat, the sample volume is 1 µl, the ionization-flame detector , the sensitivity of the device is 1/20, the column is connected to the sample input unit through a flow divider. The numbers indicate the peaks: 1 - n-octane, 2 - n-nonane, 3 - n-decane, C p. And m e p 2. For the separation of the same mixture of normal hydrocarbons on the proposed columns, the following conditions are optimal: gas pressure the carrier at the inlet is 1.5 atm, the temperature in the thermostat is 120 C. Other conditions are similar to example 1. In FIG. Figure 6 shows the chromatogram obtained under these conditions on the same column as in Example 1, consisting of one peak. Froze FIG. Figure 7 shows the chromatogram of a mixture of normal hydrocarbons, obtained under the conditions described in Example 2 on the proposed 30 m long column with an internal tube-casing diameter of 0.8 mm without using a flow divider. The number of capillaries in casing tube 1, the ratio of the effective cross-sectional area of the intercapillary space to the cross-sectional area of the capillary is 3: 1. The numbers indicate the peaks: 1 — the peak corresponding to the mixture of hydrocarbons in the intercapillary space, 2 — n-octane, 3 — n-nonane, 4 — n-decane. Example 4. FIG. 8 shows the chromatogram of a mixture of normal hydrocarbons, obtained under conditions similar to example 3, on the proposed column with a length of 30 m and an internal diameter of the tube-casing of 0.8 mm. The number of capillaries in casing tube 1, the ratio of the effective cross-sectional area of the intercapillary space to the cross-sectional area of the capillary is 10: 1. PRI me R 5. FIG. 9 shows the chromatogram of a mixture of hydrocarbons, obtained under conditions similar to example 3, on the proposed column 30 m long with an internal diameter of the tube-casing 0.8 mm. The number of capillaries in the casing tube 3, the ratio of the effective cross-sectional area of the intercapillary space to the sum of the cross-sectional areas of the capillaries is 3: 1. The digital designation of the peaks in the chromatogram is the same as in examples 3-4. PRI me R 6. FIG. 10 shows the chromatogram of a mixture of hydrocarbons obtained analogously to the example.

3, on the proposed column with a length of 30 m, an internal tube diameter of 0.8 mm. The number of capillaries in the housing-casing 3, the ratio of the area of the effective cross section. They are 10: 1 to the cross-sectional area of the capillary cross section.

The digital designation of the peaks is the same as in examples 3-5.

The chromatograms obtained on the proposed columns (Fig. 7-10) differ from the chromatographs obtained on a known column (Fig. 5) by the presence of an additional peak due to splitting of the t-carrier flow inside the column and the difference in the speeds of its movement in intercapillary space and inside capillary

By comparing the area of this peak and the area of the peaks of substances leaving the capillaries, it is possible to accurately calculate the amount of discharge at the inlet to the column. The value of the following peaks can also be directly estimated by the value of the additional peak and the required sensitivity of the instrument should be set in advance.

Thus, the proposed columns solve the problem of introducing the sample into the columns without using special devices for dividing the flow while accurately estimating the amount of the substance entering the capillaries. Thanks to the protective cover, it is possible to work with ultrathin capillaries, as well as a significantly greater separation efficiency. The mobile phase emerging from the intercapillary space at high speed effectively flushes the internal cavities of the detector, reducing the residence time of separated substances in them, which significantly reduces the requirements for connecting the column to the detector.

In addition, since the gas-carrier fluxes are split directly inside the proposed columns, the exploration of substances is excluded into the atmosphere, which significantly improves the working conditions with standard chromatographic instruments.

 the invention

Claims (3)

1. Chromatography column o a glass capillary, characterized in that, in order to simplify operation and improving the accuracy of controlling splitting of the mobile phase, inside 5 glass capillary there is at least one glass capillary of the same length but smaller diameter. 2. Column according to claim 1, about t l and h.:; 0 y with the fact that the cross-sectional area of the intercapsular space is larger than the sum of the cross-sectional area of the caps.)) 3, located 3 3-10 times inside. 3. A method for producing a chromatographic column according to claims. 1 and 2 by heating the glass tube to soften and stretch it, so that V. So, nepe / j, by heating and stretching the tube of it, tightened the tubes of smaller diameter with the ratio of the cross-sectional areas, which is indicated in clause 2, is sealed to the neyvaea Ie ends and then the tubes are heated and drawn 5 to obtain a capillary. Sources of information taken into account in the examination 1. Golbertk. and others. Course gas chromatography, M., 1967, p. 20-31. 0 2. Dijkstra G. et al. Gas chromatography, M., IIL. 1961, p. 62 (prototype). fig.Z figl 1 g four . (put.5. AL Jui -,)  ZI 2 / g2mi.