RU2570705C1 - Immobile phase for gas chromatography - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: described is immobile phase for gas chromatography, which represents functionalised polymer, obtained by oxidative processing of poly(1-trimethylsilyl-1-propine) with nitrous oxide.

EFFECT: possibility to separate different classes of chemical compounds with high degree of selectivity, with temperature and column size is rendering strong influence on holding of components.

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Description

The invention relates to analytical chemistry, specifically to stationary phases for the separation of substances by capillary gas chromatography, and can be used in the analysis of various classes of chemicals.

For the separation of mixtures of inorganic and organic compounds by gas chromatography, organic stationary liquid phases of various polarity are usually used, for example, oxypropionitrile, polyethylene glycol, polyethylene glycol succinate, etc. [SU 544913, G01N 31/08, 01/30/1977].

However, such phases do not have a sufficiently high selectivity for hydrocarbons with close boiling points, in particular for isomers, or, having good selectivity, are characterized by a long retention time. For these phases, selectivity in the homologous series of polar compounds is practically absent.

The known method and the stationary phase for the analysis of volatile organic compounds by vapor phase chromatography. The stationary phase in its composition contains an aqueous solution of N-methylmorpholine-N-oxide [SU 771543, G01N 31/08, 10/15/1980].

The disadvantage of this method is that it does not allow to achieve separation of a mixture of light hydrocarbons, freons, sulfur-containing compounds.

The stationary phase and the method of chromatographic analysis with its application are known [RU 2018822, G01N 30/50, 08/30/1994; SUPELCO Chromatography. Products for analysis and purification. P. 214-215], which allow in many cases to realize high selectivity in the analysis of polar compounds of various classes.

However, at this phase, chromatographic analysis occurs under programmed conditions and is characterized by long retention times for most classes of compounds to be analyzed.

The closest technical solution to the proposed invention are the stationary phase based on divinylbenzene and the method of chromatographic analysis with its application [Drugov Yu.S., Konopelko L.A. Gas chromatographic analysis of gases. Moscow: MOIMPEX, 1995 S. 278-283], which also allow selective separation of mixtures of polar compounds.

However, in some cases, when analyzing complex mixtures of substances containing, for example, hydrocarbons and sulfur-containing compounds, structural isomers of aromatic hydrocarbons, freon mixtures showed insufficient selectivity and the observed peaks of the substances separated were asymmetric.

The objective of the invention is the creation of a stationary liquid phase, the use of which will provide high selectivity for the separation of inorganic and organic compounds, including polar compounds.

To solve this problem, a stationary phase for gas chromatography is proposed, the basis of which, according to the invention, is a functionalized polymer obtained by the oxidative treatment of poly (1-trimethylsilyl-1-propine) (PTMSP) with nitrous oxide.

The PTMSP sample used is a glassy polymer from the class of unsaturated polyacetylenes, subjected to oxidative treatment with nitrous oxide. With this treatment [RU 2230754, C08F 8/06, 06/20/2004] double C = C bonds of unsaturated polymers react with nitrous oxide to form carbonyl (aldehyde and ketone) groups, which significantly change the polarity of the PTMSP obtained during the nitrous treatment nitrogen. A change in the polarity of the polymer leads to selective separation, including polar oxygen-containing compounds.

Modification PTMSP as follows.

0.15 g of the indicated polymer and 60 cm ^{3 of} toluene as a solvent are charged into a 100 cm ³ stainless steel reactor. Air is removed from the reactor by vacuum evacuation and then nitrous oxide is injected to an initial pressure of 15 atm. The reaction is carried out at 220 ° C for 96 hours

A sample of functionalized PTMSP in an amount of 0.1000 g is placed in a 50 ml glass flask, 20 ml of toluene are added and stirred on a magnetic stirrer for 4 hours. A quartz capillary 0.32 mm in diameter and 15 to 30 m in diameter is filled with the prepared solution. , a polymer film thickness of 0.5 μm connect the column to an inert gas source (argon) and purge with an inert gas for one hour at a temperature of 200 ° C. Then the temperature of the thermostat is increased to 220 ° C. Under these conditions, the column is conditioned with argon for 4 hours.

A chromatographic capillary column, on the inner surface of which a film of oxidized PTMSP is uniformly applied, is used in the analysis of various classes of chemicals. The temperature of the chromatographic column during the analysis is varied in the range from 25 to 220 ° C.

Analysis of reaction mixtures is carried out using three types of detecting devices: a micro-detector for thermal conductivity (micro-accident), a flame ionization detector (PID), and a quadrupole mass spectrometer (sq. MS).

The invention is illustrated by the following examples and FIG. 1-9.

Example 1

A mixture of gases of saturated and unsaturated hydrocarbons (C ₁ -C ₄ ) is analyzed. Analysis conditions: chromatographic column 30 m × 0.32 mm × 0.5 μm, filled with a stationary phase as described above. Column temperature 50 ° C, pressure 0.45 atm, evaporator temperature 200 ° C, detector temperature 220 ° C, sample volume 10 μl, carrier gas - helium, PID. Analysis time 10 min.

In FIG. 1 shows a chromatogram obtained under the indicated conditions for the separation of a mixture of gases of saturated and unsaturated hydrocarbons (C ₁ -C ₄ ). The chromatogram clearly shows the separation of all components of the mixture: 1 - methane; 2 - acetylene; 3 - ethylene; 4 - ethane; 5 - propylene; 6 - propane; 7 - 1,3-butadiene; 8 - 1-butene; 9 - isobutane; 10 - n-butane. It should be noted that in this stationary phase, a unique order of component exit is observed when acetylene elutes before ethylene.

In FIG. Figure 2 shows the chromatogram obtained under the indicated conditions for the separation of a mixture of gases of saturated and unsaturated hydrocarbons (C ₁ -C ₂ ). The order of release of components of the same composition and under similar conditions, with the exception of a pressure of 0.62 bar, differs on a capillary column with divinylbenzene Rt-Q-BOND (prototype), namely, acetylene elutes after ethylene, and the analysis time for C ₁ hydrocarbons only C ₂ is 20 minutes, the release time of C ₃ -C ₄ hydrocarbons is well over 50 minutes.

1 - methane; 2 - acetylene; 3 - ethylene; 4 - ethane; 5 - propylene; 6 - propane.

Example 2

A mixture of aromatic hydrocarbons is analyzed. The chromatographic conditions are similar to those in Example 1, with the exception of the temperature of the chromatographic column, which in this example is 160 ° C, the sample volume is 0.2 μl.

In FIG. 3 shows the separation chromatogram obtained under these conditions, in which: 11 - benzene; 12 - toluene; 13 - ethylbenzene; 14 - m-xylene; 15 - p-xylene; 16 - o-xylene.

Example 3

A mixture of air, carbon dioxide, sulfur components and C ₁ -C ₂ hydrocarbons is analyzed. Analysis conditions: column temperature 25 ° C, evaporator temperature 150 ° C, detector temperature 200 ° C, sample volume 10 μl, carrier gas - helium, micro-accident.

In FIG. 4 presents the separation chromatogram obtained under these conditions, on which the main components are identified: 17 — air + methane; 18 - carbon dioxide; 2 - acetylene; 3 - ethylene; 19 - hydrogen sulfide; 4 - ethane; 20 - sulfur dioxide.

Example 4

A mixture of thiophene and aromatic hydrocarbons is analyzed. The initial column temperature is 120 ° C, holding for 5 minutes, then programmed heating at a rate of 12 ° C / min to 170 ° C, holding for 2.5 minutes; evaporator temperature 240 ° C, detector temperature 240 ° C, sample volume 0.5 μl, carrier gas - helium, PID.

It should be noted that in this stationary phase, a unique order of the components is observed when thiophene elutes in front of benzene. The analysis time is 10 min; all peaks in the chromatogram are Gaussian.

In FIG. 5 shows the separation chromatogram obtained under these conditions, in which: 21 is thiophene; 11 - benzene; 12 - toluene; 22 - methylcyclohexane; 23 - n-heptane.

In FIG. Figure 6 shows a chromatogram for separating a mixture of the same composition and under the following chromatographic conditions: the initial temperature of the column is 120 ° C, holding for 3 minutes, then programmed heating at a rate of 12 ° C / min to 200 ° C, holding for 2.5 minutes; evaporator temperature 240 ° C, detector temperature 240 ° C, sample volume 0.5 μl, carrier gas - helium, PID, on a capillary column with divinylbenzene Rt-Q-BOND (prototype): 21 + 11 - thiophene + benzene; 12 - toluene; 22 - methylcyclohexane; 23 - n-heptane. The order of release of the components is different, namely, thiophene and benzene come out in one peak, the analysis time is 23 minutes, the peaks of methylcyclohexane, toluene are wide and somewhat asymmetric.

Example 5

A mixture of chlorine-containing compounds is analyzed. Column temperature 160 ° C, evaporator temperature 200 ° C, detector temperature 220 ° C, sample volume 0.2 μl, carrier gas - helium, PID.

In FIG. 7 presents a chromatogram of a mixture of chlorine-containing compounds:

24 - methylene chloride, 25 - chloroform, 26 - dichloroethane, 27 - carbon tetrachloride.

Example 6

A complex mixture of freons is analyzed. The initial column temperature is 50 ° C, holding for 5 minutes, then programmed heating at a speed of 12 ° C / min to 200 ° C, holding for 5 minutes; evaporator temperature 200 ° C, detector temperature 200 ° C, sample volume 10 μl, carrier gas helium, quadrupole MS.

In FIG. 8 presents a chromatogram of the analyzed mixture of substances obtained under these conditions. The identified components of the mixture: 17 - air + methane, 28 - freon 125 (pentafluoroethane), 29 - freon 115 (pentafluorochloroethane), 30 - freon 124 + 24a (tetrafluorochloroethane), 31 - freon 133a (trifluorochloroethane), 32 - freon 114a (tetrafluorodichloroethane ), 33 - Freon 1112 (difluorodichloroethylene), 34 - Freon 123 + 123a (trifluorodichloroethane), 35 - Freon 113 (trifluorotrichloroethane), 36 - Freon 1111 (fluorotrichloroethylene), 37 - Freon 122 (difluorotrichloroethane), 38 - Perchlorethylene.

Example 7

A mixture of alcohols is analyzed. Column temperature 130 ° C, evaporator temperature 220 ° C, detector temperature 200 ° C, PID. High separation selectivity was noted and the shape of the peaks was symmetrical (Fig. 9):

39 - ethanol, 40 - 1-propanol, 41 - isobutanol, 42 - 1-butanol, 43 - isoamyl, 44 - amyl.

The table shows the data obtained using the proposed stationary phase on retention of the resolution of peaks (Rs) of compounds of various chemical nature at different temperatures (25–220 ° C) and different lengths of the chromatographic capillary column (15–30 m).

The capillary column resolution (Rs) is calculated by the formula:

Rs = 2 × (t _R2 -t _R1 ) / (w ₁ + w ₂ ),

where t _R2 , t _R1 is the uncorrected retention time; w ₁ , w ₂ is the width of the peaks of these two compounds at the base, measured between the intersection points of the tangents to their sides with a zero line and expressed in the same units as the numerator.

As can be seen from the table, the proposed stationary phase allows you to separate with a high degree of selectivity a wide variety of classes of chemical compounds. In this case, the temperature and column size have a strong effect on the retention of the components.

Claims (1)

The stationary phase for gas chromatography, characterized in that it is a functionalized polymer obtained by the oxidative treatment of poly (1-trimethylsilyl-1-propine) with nitrous oxide.

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