CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2017/033294 filed Sep. 14, 2017.

TECHNICAL FIELD

The present invention relates to a jig used to connect an ionization probe of an ion measurement device to a column of a liquid chromatograph and an ionization probe connected by the jig used in the liquid chromatograph that measures various components separated by the column of the liquid chromatograph by ionizing the various components, a liquid chromatograph having an ionization probe connected by the jig, and a liquid chromatograph mass spectrometer.

BACKGROUND ART

A liquid chromatograph is widely used as an apparatus that analyzes a component contained in a liquid sample. In the liquid chromatograph, the liquid sample is introduced into a column on a flow of a mobile phase, and various components contained in the liquid sample are temporally separated, and measured with a detector. The liquid chromatograph including a mass spectrometer as the detector is called a liquid chromatograph mass spectrometer. In the liquid chromatograph mass spectrometer, various components sequentially eluted from a liquid chromatograph column are ionized by introducing the various components into the ionization probe of the mass spectrometer, and the generated ions are measured in each mass-to-charge ratio.

Conventionally, the column of the liquid chromatograph and the ionization probe are connected to each other by pressing an end face on an inlet side of the ionization probe against an end face on an outlet side of the column of the liquid chromatograph fixed at a predetermined position. For example, a sleeve, a ferrule and a connection jig are used such that the sleeve has an inner diameter that gradually increases from one end toward the other end, the thread groove is formed on an inner peripheral surface of the other end of the sleeve, the ferrule is inserted into the sleeve, and the connection jig is constructed with a cylindrical push-in member in which a thread ridge corresponding to the thread groove is formed in an outer peripheral surface. The ferrule and the push-in member are attached to an end of an inlet-side flow path of the ionization probe and inserted into the sleeve, the outer peripheral thread ridge of the push-in member is screwed in the inner peripheral thread groove of the sleeve, and the ferrule is pushed into the sleeve, whereby the end face on the inlet side of the ionization probe is pressed against the end face on the outlet side of the column fixed at the predetermined position to connect the inlet side of the ionization probe and the outlet side of the column in a face abutment manner.

In recent years, a kind of liquid chromatograph mass spectrometers called nano-ESI or micro-ESI is widely used to measure a very small amount of components contained in a sample with high sensitivity. In the nano-ESI or the micro-ESI, a small-diameter column used, and the amount of eluate per unit time introduced into the ionization probe is reduced by controlling the flow rate of the mobile phase from a nL/min level to a μL/min level, which increases the charging efficiency or facilitates the solvent removal. This enhances the ionization efficiency.

When the flow rate of the mobile phase is low as described above, each component separated by the column easily diffuses due to only a small space (dead volume) in the piping after the column. For example, when a dead volume exists in the flow path between the outlet of the column and the inlet of the ionization probe, component diffuses due to the dead volume. When an unskilled user connects the column and the ionization probe using the connection jig, the push-in amount of the ferrule is insufficient, and sometimes a large dead volume is generated. For this reason, there has been proposed a technique in which using a cylindrical member instead of the ferrule of the connection jig, the dead volume at the connection portion between the column and the ionization probe is reduced by increasing the push-in amount at the inlet of the ionization probe (for example, Non Patent Literature 1).

There has also been proposed a technique of integrating the column and ionization probe with the dead volume between the outlet of the column and the inlet of the ionization probe being minimized, in order to avoid the need for the user to connect the column ionization probe (for example, Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: U.S. Pat. No. 9,095,791 B

Non Patent Literature

Non Patent Literature 1: Thermo Fisher Scientific Inc., “Thermo Scientific Dionex nanoViper Fingertight Fitting System”, [online], [searched on Jul. 24, 2017], the InternetNon Patent Literature 2: GL Sciences Inc., “Column joint format” [online], [searched on Jul. 24, 2017], the Internet

SUMMARY OF INVENTION

Technical Problem

In the liquid chromatograph mass spectrometer of micro-ESI or the nano-ESI, a compact column oven is used to efficiently control the temperature of a small-diameter column. In order to connect the ionization probe to the column set in the compact column oven using the ionization probe connection jig described in Non Patent Literature 1, it is necessary to insert a hand into the narrow space of the column oven to screw the outer peripheral thread ridge of the push-in member in the inner peripheral thread groove of the sleeve, which results in a problem in that work efficiency is poor.

On the other hand, in the configuration described in Patent Literature 1, it is not necessary for the user to perform the operation to connect the column and the ionization probe, and therefore the above problem does not occur. However, since the column and the ionization probe are integrated, only the column cannot be removed with the disposition of the ionization probe being adjusted and the ESI probe being fixed, which results in a problem in that it takes time and effort to readjust the disposition of the ESI probe every time the column to be used is exchanged:

Although the liquid chromatograph mass spectrometer is described as an example, the same problem is also generated in a liquid chromatograph including an ion analyzer (such as an ion mobility analyzer and a classifier) except for the mass spectrometer as the detector.

A problem to be solved by the present invention is to provide an ionization probe connection jig that can easily connect the inlet-side flow path of the ionization probe that is formed separately from the column and the outlet-side flow path of the column without generating a dead volume in the liquid chromatograph including the ion analyzer as the detector.

Solution to Problem

In order to solve the above problems, according to an aspect of the present invention, an ionization probe connection jig used to connect an outlet-side flow path of a column and an inlet-side flow path of an ionization probe in a liquid chromatograph includes:

a) a first element fixture fixed to a first element that is one of the column and the ionization probe;

b) a second element fixture fixed to a second element that is the other of the column and the ionization probe; and

c) a movement regulating tool configured to permit the first element fixture to advance in an axial direction of the first element and to restrict the second element fixture such that the second element fixture does not retreat beyond a predetermined position in an axial direction of the second element, while regulating the first element or the first element fixture and the second element or the second element fixture such that flow paths of the first element and the second element are aligned with each other.

When the ionization probe connection jig of the present invention is used, the first element fixture is fixed to the first element that is one of the column and the ionization probe, and the second element fixture is fixed to the second element. The both are attached to the movement regulating tool. Consequently, the flow path of the first element and the flow path of the second element are aligned. The first element fixture is permitted to advance in the axial direction (the direction in which the flow path extends) of the first element (movement in the direction toward the second element), and the second element fixture is regulated so as not to retreat (move backward from the first element) beyond a predetermined position in the axial direction of the second element. At this point, when a user applies force to advance the first element fixture, the flow path of the first element and the flow path of the second element abut on each other. The both move in the same direction (the first element advances and the second element retreats). Subsequently, when the second element fixture is retracted to the predetermined position, further movement is restricted by the movement regulating tool, and the flow path of the first element is pressed against the flow path of the second element. Consequently, the flow path of the first element and the flow path of the second element are connected to each other in a face abutment manner. In the ionization probe connection jig according to the present invention, it is only necessary to push the first element fixture toward the second element fixture, but it is not necessary to screw a narrow space of a connection point of the column and the ionization probe unlike the conventional technique, so that work efficiency is improved. The column and the ionization probe that are separately formed are used, so that only the column can be removed with the disposition of the ionization probe being adjusted and the ionization probe being fixed.

Preferably the ionization probe connection jig according to the present invention further includes d) a pressing mechanism configured to press the first element fixture so as to advance the first element fixture.

In this aspect, a force point of the pressing mechanism is disposed in a wide space in consideration of the disposition of each unit of the liquid chromatograph, which allows workability to be further improved. The pressing mechanism may directly press the first element fixture, or press the first element fixture fixed to the first element by pressing the first element (that is, indirectly press the first element fixture).

In the ionization probe connection jig according to the present invention, preferably the first element is a column, and the first element fixture is fixed to an end an outlet side end of the column.

When the first element fixture is fixed to the end on the inlet side of the column or the main body of the column, force pushing the first element fixture is transmitted to the connection portion to the ionization probe through the main body of the column. For this reason, it is necessary to carefully apply force during use of a column, such as a capillary column, which is easily damaged. On the other hand, when the first element fixture is attached to the end on the outlet side of the column, the force pushing the first element fixture is transmitted to the connection portion to the ionization probe with no use of the main body of the column, so that any careful operation is not required even if the capillary column or the like is used.

In the ionization probe connection jig of the aspect in which the first element fixture is fixed to the end on the outlet side of the column, preferably a through-hole is made at a position corresponding to a flow path of the column in the first element fixture, and the through-hole includes a tapered portion in which an inner diameter increases from a side on which the column is located toward a side on which the ionization probe is located.

In this aspect, the inlet-side piping of the ionization probe can easily be inserted into the through-hole. When the inlet-side piping of the ionization probe is inserted, the inlet-side flow path of the ionization probe is guided to a position of the outlet-side flow path of the column in the through-hole, so that the connection is precisely performed to be clear of worry about generation of liquid leakage.

In the ionization probe connection jig according to the present invention, preferably the first element fixture is detachably held on the liquid chromatograph.

Consequently, the column fixed to the first element fixture and the ionization probe connected to the column (or the ionization probe fixed to the first element fixture and the column connected to the ionization probe) are held on the liquid chromatograph, so that undesired desorption or diffusion of components in the liquid sample due to a vibration of the column the ionization probe by the vibration outside the apparatus can be prevented. The first element fixture may be fixed indirectly to the liquid chromatograph (for example, to the casing detachably attached to the liquid chromatograph).

In the ionization probe connection jig of the aspect in which the first element fixture having the through-hole is detachably held in the liquid chromatograph, preferably the first element fixture is held by the liquid chromatograph so as to be rotatable about a center axis of the through-hole.

Consequently, after the first element fixture is attached to the liquid chromatograph, the fixture can be rotated to eliminate twist of the flow path and the like connected to the inlet-side flow path of the column. In this aspect, preferably the first element fixture includes a disk-shaped portion.

Preferably the ionization probe connection jig of the aspect in which the first element fixture is held by the liquid chromatograph further includes e) an operation member detachably attached to the first element fixture. In this aspect, in performing an operation such as accommodation of the column and the first element fixture fixed to the column in the column oven, the user can select an operation member having an appropriate shape and size, and safely and easily attach the connection jig without touching a high-temperature column oven or the like.

In the ionization probe connection jig according to the present invention, preferably the pressing mechanism includes an elastic member having elasticity in the axial direction of the first element. Consequently, even if the user applies excessive force to the pressing mechanism, a part of the force is absorbed by the elasticity of the elastic member (for example, a spring), so that damage to the column and the ionization probe can be avoided. The column is manufactured by different companies, and the length of the piping protruding from the outlet of the column varies depending on the company and the type of the column. When the pressing mechanism having a configuration including the elastic member is used, the difference in the length of the piping can be absorbed and the end face on the outlet side of the column and the end face on the inlet side of the ionization probe can certainly be connected to each other in the face abutment manner.

In the ionization probe connection jig of the present invention, preferably the first element fixture is fixed to the column by a unified screw.

As described above, the column is manufactured by different companies, and the shape of the column varies depending on the manufacturing company and the type of column. However, for example, as described in Non Patent Literature 2, a connector conforming to the unified screw (inch screw) standard can be attached to many of them, so that the ionization probe connection jig can correspond to different types of columns having different shapes.

According to another aspect of the present invention, in an ionization probe connected to a column by the ionization probe connection jig, an area of an end face on an inlet side is smaller than a sectional area of a portion except for the end face. Consequently, the force required to connect the end face on the outlet side of the column and the end face on the inlet side of the ionization probe in the face abutment manner can be smaller. Thus, the force required to advance the first element fixture is decreased, and even a powerless person can easily connect the end face on the outlet side of the column d the end face on the inlet side of the ionization probe in the face abutment manner.

In the ionization probe, preferably an end on the inlet side is tapered. Consequently, the force applied to the first element fixture can be dispersed, and deformation and breakage at the end on the inlet side of the ionization probe can be prevented to improve durability.

Advantageous Effects of Invention

The use of the ionization probe connection jig of the present invention can easily connect the inlet-side flow path of the ionization probe that is formed separately from the column and the outlet-side flow path of the column without generating a dead volume in the liquid chromatograph.

