JPH06249934A - Sample tube for NMR - Google Patents

Abstract

PURPOSE:To obtain NMR (nuclear magnetic resonance absorption analysis) spectrum with a high resolution using a small amount of sample by forming a spherical cavity within a cylinder which is inserted into a coil for analysis and then penetrating a capillary hole leading to the cavity from the upper edge along the center line of the cylinder. CONSTITUTION:A test tube 1 is a cylinder made of glass, a spherical cavity 3 is formed at the center part, and then a capillary hole 4 is penetrated to the cavity 3 along the axis of the cylinder from the upper edge. A coil 2 for analysis and the test tube 1 are placed in a static magnetic field H. A sample liquid solution S is allowed to flow from the capillary hole 4 to fill in the cavity 3 and no liquid solution S is filled into the capillary hole 4 itself. Since the test tube 1 is made of a diamagnetic material, no static magnetic field at the upper and lower both edge parts is disturbed due to the test tube itself when a constant magnetic substance is mixed for forming a nonmagnetic or a weak constant magnetism. When the outer diameter of the test tube 1 is made uniform and the test tube 1 is extended fully longer so that both edges completely leave the upper and lower both edges of the coil 2, even a slight flow of magnetic field at the upper and lower both edges of the test tube 1 does not reach the location of the sample, thus further reducing disturbance of the magnetic field.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improvement of a sample tube for NMR (nuclear magnetic resonance absorption analysis).

[0002]

2. Description of the Related Art A conventional NMR sample tube has a test tube shape as shown in FIG. 2 and is inserted into an NMR apparatus. N
The MR device forms a strong static magnetic field H in the tube axis direction of the sample tube, and the sample tube 1 has an analysis coil 2 placed in this magnetostatic field.
Inserted inside. In this case, since the sample solution generally has a different magnetic permeability from that of air, the static magnetic field is disturbed at the upper and lower ends of the sample solution S in the sample tube. If the disturbance of the static magnetic field reaches the area surrounded by the analysis coil 2, N
Since the resolution of the MR spectrum is reduced, the upper and lower ends of the sample solution are positioned further up and down outside the upper and lower ends of the analysis coil. Therefore, the sample solution has a volume in the area surrounded by the analysis coil. The above amount was required, and it was difficult to analyze a trace amount sample. Further, as described above, even if the extra sample is used and the disturbed portions of the magnetic field at the upper and lower ends are located outside the area of the analysis coil, the magnetic field in the sample solution cross section in the analysis coil area is Since it is not uniform, correction work (shimming) is required, and the degree of non-uniformity of the magnetic field in the cross section of the sample solution differs depending on the magnetic permeability of the sample solution, so it is necessary to perform shimming again for each sample. Was troublesome.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to provide an NMR sample tube which has a high resolving power even with a small amount of sample solution and does not need to perform shimming again for each sample.

[0004]

A spherical (generally ellipsoidal) cavity is formed in a cylindrical body to be inserted into an analysis coil, and the cavity extends from the upper end along the centerline of the cylindrical body. The sample tube was made by penetrating the narrow tube hole.

[0005]

When a sphere (generally an ellipsoid) is placed in a uniform magnetic field, the inside of the body is magnetized uniformly regardless of the magnetic permeability, and the magnetic field inside the body is uniform even if the magnetic field outside the body is disturbed. It becomes uniform. In the case of an ellipsoid, even if the ellipse axis is inclined with respect to the outer uniform magnetic field, the magnetic field inside the ellipsoid is uniform, and the direction of the magnetic field inside the object is different from the external magnetic field. . In the case of the present invention, the sample is filled in the cavity of the ellipsoid, and the ellipse axis of the cavity is parallel to the static magnetic field of the NMR apparatus, so that a uniform magnetic field in the same direction as the static magnetic field is formed in the sample, Since there is no place where the magnetic field is disturbed in the sample, the size of the cavity can be entirely within the analysis coil area, and it is not necessary to fill the outside of the analysis coil area with the sample solution.
An NMR spectrum with high resolution can be obtained even with a small amount of sample, and since the magnetic field in the sample is uniform, it is not necessary to perform shimming again for each sample.

[0006]

EXAMPLE FIG. 1 shows an NMR sample tube according to an example of the present invention. Reference numeral 1 denotes a sample tube, which is a cylindrical body made of glass, in which a spherical cavity 3 is formed in the central portion, and a thin tube hole 4 is made to penetrate from the upper end to the cavity 3 along the axis of the cylindrical body. Reference numeral 2 is an analysis coil, and the analysis coil and the sample tube 1 are placed in a static magnetic field H. The sample solution S is injected from the capillary hole 4 so as to fill the inside of the spherical cavity 3. The capillary hole 4 itself is not filled with the sample solution. On the contrary, if the sample solution is filled into the narrow tube hole, the magnetic field in the sample is disturbed.

The sample tube 1 is made of glass, but since glass is a diamagnetic material, if a paramagnetic substance is mixed into the sample tube to make it nonmagnetic or weakly paramagnetic, the static magnetic field at the upper and lower ends of the sample tube itself will be Disturbances are very small. If the outer diameter of the sample tube is made uniform and the length is sufficiently long so that both ends are sufficiently separated from the upper and lower ends of the analysis coil 2, even a slight disturbance of the magnetic field at the upper and lower ends of the sample tube will reach the sample. Since the static magnetic field can be regarded as uniform in the area of the analysis coil, the disturbance of the magnetic field is further reduced as compared with the case where the material of the sample tube is simply made non-magnetic. If both upper and lower ends are rounded, it is convenient that the entire sample tube can be regarded as an elongated ellipsoid. Although the shape of the cavity is a sphere in the above-mentioned embodiment, it may be elongated or flat as long as it is an ellipsoidal shape as described above, as long as one of the ellipse axes is parallel to the direction of the static magnetic field. The magnetic field in the sample solution in the cavity is also parallel and uniform with the static magnetic field. So the sphere is a special kind of ellipsoid. Further, if the magnetic permeability of the sample tube is almost the same as that of air, the sample tube does not have to have a shape with a constant outer diameter as shown in FIG. 1, but may have the shape of a thin tube in which only the sample portion is inflated.

[0008]

According to the present invention, a large amount of sample is not required in order to prevent the disturbed portion of the magnetic field from entering the area of the analysis coil. Since it is possible to analyze with a sample amount that fills a small volume, there is no waste of sample, and it is possible to analyze a sample that can be obtained only in a small amount. It is possible to obtain a high-resolution NMR spectrum, eliminating the need for shimming for each sample, improving the efficiency of analysis work, and reducing the amount of sample required. The deviation of tuning to high frequency is small, and the analyzer is easy to handle.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a sample tube according to an embodiment of the present invention.

FIG. 2 is a side view of a conventional sample tube.

[Explanation of symbols]

 1 Sample tube 2 Coil for analysis 3 Cavity 4 Capillary hole S Sample solution

Claims (1)

[Claims] An NMR sample tube characterized in that an ellipsoidal cavity is formed in a portion for accommodating a sample, and elongated tubes are connected in the uniaxial direction.