JPH0413966A - Quartz glass capillary column - Google Patents

Abstract

PURPOSE:To prevent increase in cost as caused by consumption of a capillary column by providing a solid phase on an internal surface of a part except for near both ends of a quartz glass capillary column. CONSTITUTION:In order to form a solid phase 3 except for a terminal 24 of a quartz glass capillary 1, for example, the quartz glass capillary 1 is filled with a solution of a solid phase 3 forming material over the entire length thereof and a solvent is evaporated at a relatively low temperature by a static method to form a layer of the solid phase 3 forming material over the entire length of the quartz glass capillary 1. Then, the solid phase 3 forming material is crosslinked by heating a part alone to form the solid phase 3 or by irradiating it with an electron beam, gamma rays or the like and the solid phase 3 forming material yet to be crosslinked is eluted by a proper solvent. In the crosslinking by heating, an isolated group forming agent to the solution of the solid phase 3 forming material is added beforehand and heated above a temperature at which the isolated group is generated.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to fused silica capillary columns.

In particular, it relates to a quartz glass capillary column suitable for the analysis of high-boiling compounds and retention gap methods.

[Conventional technology]

Quartz glass capillary columns are used in gas chromatography,
liquid chromatography, supercritical fluid chromatography,
It is useful as a separation column for ion chromatography, electrophoretic analysis, etc. Columns using silica glass capillaries have superior properties compared to conventional packed columns and columns using metals such as SUS stainless steel or multi-component glass capillaries, and further development is expected in the future. A silica glass capillary column has superior separation performance compared to, for example, a packed column, and has fewer impurities, so it has the advantage of less tailing due to adsorption than a column using a capillary made of metal or multi-component glass.

Fused silica capillaries usually have an outer diameter of 0.2 to 1.0
It is a thin film with a thickness of about 0.05 to 0.2 mm, and is used at high temperatures of 250°C or higher in gas chromatography, or 350°C or higher depending on the purpose, so the protective film is usually made of a heat-resistant material. be done.

To manufacture a quartz glass capillary column, a quartz glass capillary is drawn from an anhydrous synthesized quartz glass base material in a drawing furnace, and immediately after drawing, the outer surface is made of a heat-resistant resin such as polyimide resin or a metal such as aluminum. After coating with a heat-resistant protective layer, the inner surface of the capillary is
A surface treatment is performed using silylation or a silane coupling agent, and a stationary phase made of polydimethylsiloxane, polyethylene glycol, etc. is formed. The surface treatment is
This is to inactivate the hydroxyl groups present on the glass surface.

To perform gas chromatography analysis using a quartz capillary column, a capillary column 33 is connected between a sample injection port 31 and a detection section 32, as shown in FIG. When analyzing a high boiling point compound, the temperatures of the sample injection port 31, capillary column 33, and detection section 32 are all raised. In particular, the temperature of the sample injection port 31 and the detection section 32 must be kept 30 to 100°C higher than the temperature of the capillary column 33, and may reach 350 to 400°C.

When performing analysis by injecting a relatively large amount of sample into a quartz capillary column, in order to prevent tailing of solvent peaks and abnormal diffusion of solute peaks, it is necessary to 43, an aerodynamic ram 44 having no stationary phase is connected via a connector 45, which is called a retention gap method. The following requirements are required for the connector 45 that connects the separation column 43 and the aerodynamic ram 44.

(1) Completely inactivated to prevent adsorption of polar compounds (2) Mechanical strength (3) Heat resistance (4) Easy to connect (5) Low price Usually made of glass Or a metal connector is used.

[Problem to be solved by the invention]

However, in the configuration of conventional gas chromatography, when analyzing high-boiling compounds, the temperature at and around the end of the capillary column inserted into the sample injection port and detection section is 3.
The temperature can reach as high as 50 to 400°C, and the separation performance of the stationary phase on the inner surface of this portion is likely to deteriorate. This deterioration is significant when the carrier gas contains a trace amount of oxygen. Once a quartz capillary column undergoes such thermal or oxidative degradation, it can no longer recover. Therefore,
Conventionally, several meters of both degraded end portions were cut off and the remaining portion was used, which caused the problem that the length of the capillary column became shorter each time the length of the capillary column was cut off, resulting in a gradual decline in the separation capacity of the capillary column. there were. At the end, not only the separation ability but also the mechanical strength decreases due to the high temperature. When the column length is less than a certain value, the capillary column becomes unusable due to a drop in separation ability and must be replaced with a new capillary column, increasing the cost of analysis.

The retention gap method also had problems with the connectors used to connect the separation column and the aerodynamic ram. In other words, glass connectors have poor mechanical strength (requirement (2) above), and metal connectors have excellent mechanical strength, but complete inertization treatment on the inner surface (requirement (1))
)) is difficult and causes peak tailing of polar compounds.

Therefore, an object of the present invention is to avoid deterioration of the separation performance and mechanical strength of the stationary phase at and around the ends of a capillary column during gas chromatography analysis of high-boiling compounds, and to perform separation by cutting off the ends of the capillary column. The objective is to prevent a decrease in capacity and an increase in costs due to capillary column consumption.

Another object of the present invention is to avoid tailing of polar compound peaks or damage to the connector portion caused by the connector used to connect the separation column and the pneumatic ram in the retention gap method.

[Failure to solve the problem]

In order to achieve the above object, in the present invention, a stationary phase is provided on the inner surface of a silica glass capillary column only in a portion excluding the vicinity of both ends.

The quartz glass capillary column of the present invention has the following requirements.

(1) Quartz glass capillary (2) A stationary phase formed on the inner surface of the quartz glass capillary except for the areas near both ends.

Each element will be explained in detail below.

(1) Quartz glass capillary Usually, a capillary with an outer diameter of 0.2 to 1.0 mm and a thickness of about 0.05 to 0.2 mm is used. As usual, a relatively thick quartz glass tube base material produced by anhydrous synthesis is heated at a temperature of approximately 20°C.
It can be made by thinly drawing it in a drawing furnace at 00°C.

In a quartz glass capillary column, the inner surface of the quartz glass capillary is subjected to silylation or surface treatment with a silane coupling agent before forming the stationary phase. This surface treatment is to inactivate the hydroxyl groups present on the glass surface.

Although it is necessary to perform the surface treatment on at least the portion of the silica glass capillary where the stationary phase is to be formed, it is preferable to perform the surface treatment over the entire length.

(2) Stationary phase formed on the inner surface of the quartz glass capillary In the quartz glass capillary column of the present invention, a stationary phase having a function of component separation in gas chromatography is provided on the inner surface of the silica glass capillary except near the ends. To provide a stationary phase, either pass a solution of a stationary phase forming substance through a quartz glass capillary and then evaporate the solvent by passing a suitable inert gas (dynamic method), or pass a solution of a stationary phase forming substance into a quartz capillary. After filling, the solvent is sequentially heated and evaporated from one end (static method).

Stationary phase forming substances include, for example, polydimethylsiloxane,
Siloxanes such as phenylmethylpolysiloxane, polyethylene glycol, etc. can be used.

For example, dichloromethane, n-pentane, diethyl ether, etc. can be used as the solvent.

In order to heat the solvent in the quartz capillary in the static method, there are two methods: heating the outside of the quartz capillary by contacting a liquid with a temperature higher than the evaporation temperature of the solvent by a predetermined temperature, for example, 20°C or more, There is a method of dielectric heating using irradiation.

The end portion of the quartz glass capillary without a stationary phase is suitably in the range of 1% to 20% of the total length, including both ends.

In order to form a stationary phase except for the end of the quartz glass capillary, fill the entire length of the quartz glass capillary with a solution of a stationary phase forming substance, evaporate the solvent at a relatively low temperature using a static method, and then remove the quartz glass capillary. After forming a layer of stationary phase-forming substance along the entire length of the capillary, only the portion where the stationary phase is to be formed is heated or heated with an electron beam,
There is a method in which a stationary phase forming substance is crosslinked by irradiation with gamma rays or the like, and the uncrosslinked stationary phase forming substance is eluted with an appropriate solvent. When crosslinking is carried out by heating, a free radical forming agent is added to the solution of the stationary phase forming substance, and the solution is heated to a temperature above the free radical generation temperature.

The silica glass capillary column of the present invention may further have the following requirements as necessary.

(3) Heat-resistant protective layer provided on the outer surface of the quartz glass capillary The quartz glass capillary column of the present invention has one or more layers on the outer surface so that it can maintain mechanical strength even after repeated use at high temperatures. It may have a heat-resistant protective layer. Preferable heat-resistant protective layers used in the present invention include: (1) polyimide resins, such as aromatic polyimides, such as polycondensates of trimellitic anhydride and 4,4'-diaminodiphenyl ether (for example, DuPont's Pyr
e ML), (2) silicone-modified polyimide, that is, a polyimide having a siloxane structure in the main chain or side chain, particularly a polymer having an imide ring formed from polyamic acid and a siloxane structure in the main chain, (3) organopolysil Ruseski-oxane.

The thickness of the protective layer is preferably about 3 μm to about 50 μm. The heat-resistant protective layer may have two or more layers.

[Effect]

The quartz glass capillary column of the present invention has a distal end of 350 mm.
Even after repeated use at temperatures of °C or higher, separation performance does not deteriorate due to deterioration of the stationary phase at the end of the capillary column and its vicinity. Therefore, there is no need to cut off the deteriorated end portion, so that a decrease in separation ability due to a shortening of the length of the capillary column can be avoided. Since there is no need to replace a capillary column that has been truncated and shortened due to end trimming, the lifetime of the capillary column is increased and the costs associated with frequent replacement of the capillary column are significantly reduced.

The fused silica capillary column of the present invention eliminates the need to connect the aerodynamic ram to the separation column with a connector when utilizing the retention gap method, which would otherwise occur due to insufficient passivation in the case of metal connectors. Tailing of peaks of polar compounds or damage to the connector part in the case of glass connectors can be avoided.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1] A quartz glass capillary column according to the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section along the length of a fused silica capillary column. In FIG. 1, 1 is a quartz capillary, 2 is a heat-resistant protective film, and 3 is a stationary phase. Stationary phase 3
are provided except near the end of the capillary.

A quartz glass capillary column was manufactured as follows. First, the anhydrous synthetic quartz glass tube base material was heated to a temperature of 200°
Soften it in a drawing furnace of
It was drawn into a quartz capillary of 0 μm (tube thickness 35 μm). Immediately after stretching, the outer surface was coated with a heat-resistant resin as described below, and a stationary phase was further formed on the inner surface.

A polyimide resin solution was applied to the outer surface of the quartz capillary 1 so as to have a dry thickness of 108 m, and was dried and cured in an electric furnace at a temperature of 400°C to form a heat-resistant protective film 2.

A quartz capillary 1 coated with a heat-resistant protective film 2 has a length of 5
The quartz capillary 1 was cut to a length of 0 m, and hexamethyldisilazane was applied as a silylating agent to the inner surface of the quartz capillary 1 by the dynamic method, and heat treatment was performed at 400° C. for 16 hours to inactivate the glass surface. After that, polyethylene glycol (molecular weight 20,000) was added to the hollow part along the entire length of the quartz capillary 1.
A solution of 100 parts by weight and 3 parts by weight of dicumyl peroxide diluted with dichloromethane was charged (dicumyl peroxide is a free radical generator). Approximately 70 by static method
The solvent was evaporated by heating to 0.degree. C., forming a polyethylene glycol layer with a thickness of about 0.2 .mu.m.

Furthermore, only the portion of the quartz capillary 1 excluding 5 m of both ends was heated to about 150° C. for 60 minutes to form the stationary phase 3. After this, when the inside of the capillary column is washed with methylene chloride, uncrosslinked polyethylene glycol layers flow out from both ends of the quartz capillary 1, and the stationary phase 3 is not formed in these parts.

The quartz glass capillary column thus produced was used for analysis using the temperature-elevated column method with the configuration shown in FIG. The capillary column 23 was wound around a mandrel 23a, and both ends were connected to the sample injection port 21 and the detection section 22 of the gas chromatograph apparatus. The end portion 24 of the capillary column 23 is a portion where no stationary phase is formed on the inner surface. There was no change in the separation performance of the capillary column even after it was used 100 times for analyzes reaching a maximum temperature of 350°C.

When a higher alcohol mixture was analyzed using this column, almost no tailing was observed even for polar components, and high resolution between the components was obtained.

[Example 2] In the same manner as in Example 1, the outer surface of the quartz glass capillary 1 was coated with a heat-resistant resin 2, and the inner surface was inactivated. Polyethylene glycol (molecular weight 2 A solution (containing no free radical generator) prepared by diluting 1,000 yen) with dichloromethane was filled. By the static method, the solvent was evaporated by heating to about 70°C to form a polyethylene glycol layer with a thickness of about 0.2 μm on the inner surface, and then the quartz glass capillary was irradiated with an electron beam except for 5 m at both ends. The polyethylene glycol was crosslinked to form the stationary phase 3. Thereafter, the inside of the capillary column was washed with methylene chloride, and uncrosslinked polyethylene glycol at both ends of the quartz capillary 1 was discharged. In this way, a capillary column having the cross section shown in FIG. 1 was obtained.

〔Effect of the invention〕

According to the present invention, during gas chromatography analysis of high-boiling compounds, there is no reduction in separation performance due to deterioration of the stationary phase at and around the end of the capillary column, which is exposed to temperatures of 350°C or higher. , there is no need to cut off the end portion to maintain separation performance. Therefore, there is no reduction in separation ability due to a shortening of the total length of the capillary column, and there is no need to replace a capillary column that has been gradually truncated and shortened, so costs due to capillary column wear are significantly reduced. Since there is no stationary phase at the end of the capillary column, a decrease in mechanical strength due to high temperatures at the end of the capillary column is also avoided.

Even if the terminal end is damaged, the length of the stationary phase remains unchanged, so there is no change in separation ability.

The quartz glass capillary column according to the present invention maintains high resolution even if it is repeatedly used in gas chromatography under conditions where the sample injection port and detection area are at high temperatures of 350° C. or higher. Not only does it extend the lifetime of analysis at high temperatures, it also offers higher average resolution than before.
Obtained stably.

In addition, according to the present invention, during analysis by the retention gap method, a separation column and an aerodynamic ram (a column without a stationary phase) are used.
Since there is no need to use a connector to connect the aerodynamic ram, there is no need to use a connector to connect the aerodynamic ram, and there is no need to worry about tailing of polar compound peaks caused by metal connectors or damage that can easily occur when using glass connectors. can avoid.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the silica glass capillary column according to the present invention, FIG. 2 is a diagram showing how the silica glass capillary column according to the present invention is used four times, and FIG. Explanatory diagram showing the state, No. 4
The figure is an explanatory diagram showing how a silica glass capillary column is used in the retention gap method. Explanation of symbols 1------- Monosilica glass capillary 2---
-----1 Heat-resistant protective film 3----1 stationary phase 21---1 sample injection port 22---1 detecting section 23---Capillary column 23 a- ------- Mandrel 24 ------- End part 31 without stationary phase
-1 Sample injection port 32--1 Detection section 33--Capillary column 43--Separation column 44-1.-Aerodynamic ram 45--Connector bar Bonito Loco Self-binding To Exposure < Medium Δ e + cy (One O sample injection port detection part capillary column 44 sample injection port detection part separation column - aerodynamic ram connector 3rd 4th

Claims (3)

[Claims] (1) A quartz glass capillary column characterized in that a stationary phase is provided on the inner surface only in a portion of the quartz glass capillary excluding the vicinity of the end. (2) The quartz glass capillary column according to claim 1, wherein the inner surface of the quartz glass capillary is subjected to an inactivation treatment over its entire length. (3) The quartz glass capillary column according to claim 1, wherein the vicinity of the end of the quartz glass capillary, which is not provided with a stationary phase, accounts for 1 to 20% of the total length.