JPH10206387A - Method and device to condense sample solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To condense the difficult-to-volatile substance contained in the solution by spraying and atomizing the sample solution introduced in a small pipe from a terminal of the small pipe by the gas injection flow, and recovering the ion derived from the sample solution by electrodes. SOLUTION: The sample solution is introduced in a small pipe 1. A terminal of the small pipe 1 is installed in the vicinity of a gas injection port 2 provided on a container 5, the gas introduced in the container 5 flows along the outside of the small pipe 1. When the gas is injected from the gas injection port 2 at the flow speed of about the sonic velocity, the sample solution is injected from the terminal of the small pipe 1, and atomized, and the sample substance in the fine droplet is taken out into the gas phase as the positive/negative ions. The substance is drifted in the direction of recovery electrodes 3a, 3b to which different voltage is applied by a power source 4a, and precipitated on its surface. The precipitated sample substance is recovered to obtain the solid sample substance, and the sample solution of high concentration can be generated by dissolving the sample substance in the solvent of arbitrary quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the field of analytical chemistry, and more particularly to a method for concentrating an analyte contained in a solution.

[0002]

2. Description of the Related Art Concentration of a sample is effective as a pretreatment for analyzing a very small amount of a sample contained in a solution. An example of a conventional sample concentration method will be described below. The gas is sent into the sample solution to generate bubbles. Volatile substances dissolved in the sample solution are vaporized by contacting the bubbles and are taken into the bubbles. For this reason, by collecting the gas accumulated in the upper part of the sample solution tank, the volatile substance in the solution can be concentrated and taken out.

[0003] There is also a method using an adsorbent for concentrating the hardly volatile substance dissolved in the solution. By bringing the sample solution into contact with the adsorbent, the sample substance is adsorbed on the surface of the adsorbent. Thereafter, the sample can be concentrated by desorbing the sample from the adsorbent. The adsorption and desorption of a sample utilizes the equilibrium between a liquid phase (sample solution) and a solid phase (adsorbent). The substance is extracted into the solvent by putting the adsorbent having the substance adsorbed in the sample solution into a solvent having a high affinity for the substance.

[0004] The sample concentrated through the above process is analyzed by an analyzer such as a gas chromatograph or a liquid chromatograph.

[0005]

The conventional sample concentration method has the following problems. In the method of sending a gas into a sample solution, it is naturally difficult to concentrate a substance having a low vapor pressure, that is, a non-volatile substance. Many biological substances such as amino acids, peptides, and proteins are hardly volatile. Therefore, in the method of feeding gas, substances that can be concentrated are limited, and biologically related substances and the like cannot be generally concentrated.

In the method of concentrating hardly volatile substances using an adsorbent, high-concentration enrichment is difficult because an equilibrium reaction between a liquid phase and a solid phase is used.

[0007] It is an object of the present invention to provide a method and an apparatus capable of concentrating a highly volatile substance contained in a solution at a high magnification.

[0008]

According to the present invention, there is provided a sample concentrating apparatus comprising: a jet port for jetting a sample solution; and an electrode for collecting ions originating from the jetted sample solution. Solve the problem. In order to collect a sample, a mechanism for applying a voltage to the electrode and cooling the electrode is provided.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. The solution is introduced into the capillary 1. The gas is introduced into the container 5 having the gas outlet 2 opened. The end of the thin tube 1 is placed near the gas ejection port 2. A solution is atomized by flowing a gas along the outside of the thin tube 1 and ejecting the gas from a gas ejection port 2. The sample substance is contained in the droplets generated by atomization. When the gas flow velocity is increased and set to about the speed of sound, extremely fine droplets are generated. Since the fine droplets are easily vaporized, the sample substance in the microdroplets is taken out into the gas phase as neutral or positive or negative ions, depending on the nature of the substance. Alternatively, even if the droplets do not completely evaporate, the solution is sprayed into the atmosphere as finely charged droplets. Therefore, the collecting electrodes 3a and 3b are provided, and different voltages are applied to the respective electrodes by the power supply 4a. Under the influence of the electric field generated between the electrodes, ions and charged droplets having positive charges drift toward the cathode, and ions and charged droplets having negative charges drift toward the anode. The sample ions and the charged droplets that have reached the electrodes 3a and 3b lose their charge when they come into contact with the electrodes, and deposit on the surfaces of the collection electrodes 3a and 3b. Therefore, the electrode surface 3
By collecting the sample deposited on a and 3b, a solid sample substance can be obtained. Therefore, a high-concentration sample solution can be prepared by dissolving with an arbitrary amount of a solvent.

The point of the concentration method of the present invention is to ionize the substance to be concentrated. Therefore, a sample having a higher ionization efficiency can be concentrated at a higher magnification. On the other hand, in the present concentration method, it is difficult to concentrate a substance having low polarity due to low ionization efficiency. The method of generating ions of a sample by a high-speed gas flow shown in FIG. 1 is also used as an ion source of a mass spectrometer, as described in Analytical Chemistry, Vol. 66, p. 4557 (1994). I have. Therefore, in the concentration method of the present invention, a substance that is easily ionized in the ion source of the mass spectrometer can be efficiently concentrated.If the sample concentrated by the concentration method of the present invention is analyzed by the mass spectrometer, the concentration is extremely high. Expected sensitivity.

When a heavy large droplet drops due to gravity and wets the recovery electrode 3b disposed at the lower part, FIG.
This problem can be solved by arranging the collecting electrode electrodes 3a and 3b vertically (that is, making the collecting electrode surface and the direction of gravity parallel) as shown in FIG.

As an example of discharging charged droplets into an electric field and utilizing the movement of the droplets, an oil droplet experiment performed by Millican is famous. In this experiment, the charge of an electron was determined by examining a charged oil droplet that was stationary in the air, where gravity and electrostatic force were balanced. However, Millikan's experiment does not consider attracting charged droplets to the electrodes and analyzing the sample attached to the electrodes because oil droplets in the air are of interest.

FIG. 3 is a diagram showing a second embodiment of the present invention. In the first embodiment, two sample recovery electrodes are provided. However, as shown in FIG. 3, an electric field is generated by applying a voltage between the electrode 5 having the gas outlet 2 and the recovery electrode 3c. If it is generated, one recovery electrode may be used. As shown in FIG. 3, if the collecting electrode is a cathode, the generated ions and charged droplets having mainly positive charges drift in the electrode direction and deposit on the electrode surface. If it is desired to collect negatively charged ions or charged droplets, the polarity of the power supply may be reversed.

FIG. 4 is a diagram showing a third embodiment of the present invention. The embodiment described with reference to FIGS. 1 and 3 is a method for collecting a solid sample deposited on the electrode surface.
In order to collect a sample more easily, a liquid form is desirable. Therefore, as shown in FIG. 4, a cooling mechanism is provided for the collecting electrodes 3a and 3b to cool the collecting electrodes 3a and 3b. FIG. 4 shows a configuration in which the collecting electrodes 3 a and 3 b are cooled by flowing cooling water through the cooling water pipe 6. Since the sample solution is sprayed, there are many solvent molecules near the recovery electrode. The solvent molecules aggregate on the cooled collection electrode surface and form dew. The sample molecules deposited on the surfaces of the collecting electrodes 3a and 3b are dissolved in the dewed solvent, so that a solution containing the sample is obtained. Thus, a concentrated sample can be obtained by collecting this solution in the collection containers 7a and 7b. This concentrated sample can be analyzed by any analysis means. As an example, a method of analyzing with a liquid chromatograph having an ultraviolet absorption detector will be described. The analyzer is
Liquid sending pump 20, injector 21, separation column 22,
It is constituted by detectors 23, each of which is connected by a pipe 24.
The mobile phase solvent is pumped up from the mobile phase solvent tank 25 and is flowed at a constant flow rate in the direction of the separation column 22 by the liquid sending pump 20. The sample collected in the collecting devices 7a and 7b is introduced from the injector 21 as it is or after performing any processing. The amount of a sample used for one analysis is about 10 microliter. The sample sent to the separation column 22 together with the mobile phase solvent is supplied to the separation column 2
Due to the interaction with the filler filled in the interior of 2, the components are separated into components. The separated sample is detected by the detector 23. Thereafter, the sample and the mobile phase solvent are collected in the waste liquid collecting device 26. The detected signal is sent to the data processing device 27 and processed.

FIG. 5 shows an example used for water quality management as a more specific embodiment of the present invention. The present concentration device is installed near the water storage tank 8. Water is pumped up from the water storage tank 8 by the liquid sending pump 9 and introduced into the thin tube 1 of the concentrator. Gas is sent from a high-pressure gas cylinder or a compressor 10, and the solution is atomized by flowing the gas outside the thin tube 1.
By providing the recovery electrodes 3a and 3b and applying a voltage, the ionized sample substance is drifted in the direction of the electrodes from the jet generated by spraying. Collection electrode 3a,
By cooling 3b, the solvent molecules are condensed on the electrodes, and are collected together with the sample molecules in the collection containers 7a and 7b. The quality of the water in the water storage tank can be managed by periodically analyzing the solution collected in the collection container or by continuously introducing the solution into the analyzer.

As described above, in the method described with reference to FIGS. 1 to 5, after generating an electrically neutral jet by spraying as a whole, ions or charged droplets contained in the jet are changed according to the charge. It is a method to collect and collect more. However, the jet itself can be pre-charged with a positive or negative charge. In the following, an embodiment will be described in which the jet itself has an electric charge.

FIG. 6 shows a configuration in which the charge induction electrode 11a is arranged near the gas ejection port. When a voltage is applied to the charge induction electrode 11a using the power supply 4b, the solution
When a gas is ejected from the electrode, a charge having a polarity opposite to the polarity of the voltage applied to the charge inducing electrode 11a is induced in the solution. Therefore, for example, when a negative voltage is applied to the charge inducing electrode 11a as shown in FIG. 6, a positive charge is induced in the sample solution that has reached the end of the capillary 1, so that the jet obtained by spraying is entirely As having a positive charge. Since a large number of positively charged ions and charged droplets are contained in the jet obtained by spraying, these are collected by the collecting electrode 3c.

As shown in FIG. 7, the induction of charging can be realized by applying a voltage to the electrode 11b of the gas outlet 2 which is open. As shown in FIG. 8, charging can also be induced by forming the container 5 itself with the gas ejection port 2 opening from metal and applying a voltage to the container 5.

The fact that the jet itself is charged means, of course, that an electric current flows through the sample solution in the capillary. For safety, a part of the thin tube 1 may be replaced with a metal tube 12 as shown in FIGS. By grounding the metal tube 12, it is possible to prevent an electric current from flowing through a liquid feed pump or the like disposed upstream of the thin tube.

In the embodiment shown in FIGS. 6 to 8, the structure is such that the charged ions and liquid droplets are attracted to the collecting electrode and collected, but as shown in FIG.
3 may be provided so that ions or charged droplets recoil in the direction of the collecting electrode 3d. As shown in FIG.
A voltage may be applied by the power supply 4d between the electrode and the collecting electrode 3c to further increase the efficiency of collecting ions and charged droplets on the collecting electrode 3c.

In the embodiment of the invention described above, the recovery electrode is described as being plate-shaped, but the shape of the recovery electrode may be arbitrary. For example, FIG. 11 shows an example in which a cylindrical recovery electrode 3d is used in the embodiment shown in FIG. By making the shape of the collection electrode 3d cylindrical, the surface area is increased, and the collection efficiency can be increased. FIG.
Indicates a collection electrode 3e with a mesh 28. When a huge droplet adheres to the collection electrode, the sample collected on the electrode surface is thinned. Further, if dust floating in the air adheres to the collecting electrode, impurities are mixed in the sample collected on the electrode surface, which is not preferable. In order to prevent such a situation, as shown in FIG. 12, a mesh 28 may be provided in front of the collecting electrode 3e to prevent huge droplets and dust from adhering to the collecting electrode.

When a concentrated sample is recovered in a liquid state as shown in FIGS. 4 and 5, the concentration ratio can be further increased by repeating concentration. As shown in FIG. 13, the sample solution is pumped up from the sample solution tank 14 by the liquid feed pump 9 and sprayed. The sample collected by the collecting electrodes 3a and 3b is dropped into the sample solution tank 14. Therefore, the concentration of the sample solution in the sample solution tank 14 gradually increases as much as the solvent is removed by spraying. FIG.
By operating the concentrator 3 for a while,
Simple concentration of the sample solution becomes possible.

In any of the cases described with reference to FIGS. 1 to 13, a collection container is provided in front of the gas ejection port, and uncharged droplets are collected in a jet generated by spraying. It is also possible. Substances that are difficult to concentrate by the concentration method according to the present invention, that is, substances that are hardly ionized by gas spraying, are contained in large amounts in uncharged droplets. Therefore, such a substance can be concentrated by collecting uncharged droplets and using a concentration method based on a principle different from that of the present invention.

[0024]

According to the present invention, substances that can be efficiently ionized in the ion source of the mass spectrometer can be selectively concentrated. Therefore, since a higher concentration ratio can be achieved as compared with the conventional concentration method, it is possible to detect a highly volatile substance in a sample solution with high sensitivity when analyzing it with a mass spectrometer.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing another method of the first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing an example in which the present invention is used for water quality management.

FIG. 6 is a diagram showing a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a fifth embodiment of the present invention.

FIG. 8 is a diagram showing a sixth embodiment of the present invention.

FIG. 9 is a diagram showing a seventh embodiment of the present invention.

FIG. 10 is a diagram showing an eighth embodiment of the present invention.

FIG. 11 is a diagram showing a case where a cylindrical collecting electrode is used.

FIG. 12 is a diagram showing a case where a collection electrode with a mesh is used.

FIG. 13 is a diagram showing a ninth embodiment of the present invention.

[Explanation of symbols]

1 ... thin tube, 2 ... gas outlet, 3a, 3b, 3c, 3d,
3e: recovery electrode, 4a, 4b, 4c, 4d, 4e: power supply, 5: container having an opening for gas outlet, 6: cooling water pipe,
7a, 7b: collection container, 8: water tank, 9: liquid feed pump,
DESCRIPTION OF SYMBOLS 10 ... Compressor, 11a, 11b, 11c ... Charge inducing electrode, 12 ... Metal tube, 13 ... Repeller electrode, 14 ... Sample solution tank, 20 ... Liquid pump, 21 ... Injector, 2
2 ... separation column, 23 ... detector, 24 ... piping, 25 ... mobile phase solvent tank, 26 ... waste liquid recovery device, 27 ... data processing device, 28 ... mesh.

Continued on the front page (72) Inventor Motoko Yoshida 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd.Central Research Laboratories

Claims (7)

[Claims] 1. A sample concentrating device comprising: a jet port for jetting a sample solution; and an electrode for collecting ions or charged droplets derived from the jetted sample solution. 2. The sample concentrator according to claim 1, wherein a voltage is applied to said electrode. 3. The sample concentrator according to claim 1, further comprising a mechanism for cooling the electrode. 4. A sample concentrating device comprising: an atomizer for atomizing a sample solution; and a wall surface for collecting a substance contained in droplets generated by atomization. 5. A sample concentrator comprising: a jet port for jetting a sample solution; and an electrode for collecting ions or charged droplets derived from the jetted sample solution, wherein the ions or the charged liquid are collected. A sample concentrating device for collecting droplets according to their polarity. 6. A method for concentrating a sample, comprising the steps of atomizing a sample solution and collecting a sample substance contained in fine particles generated by the atomization. 7. A sample analysis method comprising the steps of atomizing a sample solution, collecting a sample substance contained in fine particles generated by the atomization, and analyzing the collected sample substance.