JPS58167947A - Spinner of nuclear magnetic resonance device - Google Patents

Abstract

PURPOSE:To remove absorption spectrum (background spectrum) caused by a spinner itself by manufacturing a rotor with ceramics or glass ceramics. CONSTITUTION:As the base material of a spinner 2 to be used in the magic angle spinning method wherein a solid specimen 6 is caused to rotate around a shaft tilted by an angle of 54.7 deg. (magic angle) from the direction of magnetic field at a high speed of several kHz and by this, a sharp NMR spectrum can be obtained, a kind of ceramics or that of glass ceramics is used. The ceramics is the sinter of a composition consists of 30-96wt% of boron nitride and 70- 4wt% of a ceramics other than boron nitride, and the glass ceramics is such a substance containing fine crystals of synthetic mica which is known by the trade name of MAKORU. By the use of a spinner made of such materials, it is possible to easily obtain C13NMR spectrum of a solid specimen free from background spectrum caused by the spinner itself.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spinner used for magic angle spinning operation of a nuclear magnetic resonance apparatus (NMR apparatus), and particularly relates to a spinner used for magic angle spinning operation of a nuclear magnetic resonance apparatus (NMR apparatus).
The present invention relates to a spinner suitable for measuring an R spectrum.

Already in the literature ``c, Fundamentals and Applications of NMR, I (Takahito Takeuchi 1 Hidehiro Ishizuka, 1976, Kodansha, p. 250)
As is well known, relatively sharp NMR and spectra can be obtained even from solid samples by rotating the solid sample at a high speed of several KHz around an axis that forms a magic angle of 54° and 7 degrees with the direction of the magnetic field. can.

This method is the magic angle spinning method.

It is also called the high-speed rotation method, and the rotor used to pack the sample is called a spinner. In magic angle spinning, it is necessary to rotate the spinner at a constant high speed with little deviation from the rotating shaft, and the structure of the spinner and its rotation method are the first technical issues.

However, these problems can almost be solved by providing a part of the spinner with many small grooves that act as blades, and then blowing air into these grooves to rotate them. Figure 1 shows the spinning device. This is a diagram showing an example, in which a spinner 2 is placed on a stator 5, and a receiving high-frequency coil 1 is installed around the body of the spinner that contains a solid sample.
◇ The measurement principle for NMft is the same as that for normal liquid sample measurements; by applying a strong static magnetic field to the sample, one unit of energy of the nuclear spin of a certain atomic nucleus is separated, and this unit is It measures the resonance frequency of electromagnetic waves absorbed by the transition between

The receiving high-frequency coil 1 in Fig. 1 is for receiving high-frequency waves oscillated from an oscillating high-frequency coil (not shown), and by comparing the oscillated frequency and the received frequency, it is possible to determine which frequency corresponds to It can be determined whether or not the energy 6 has been absorbed. It is better to place the receiving high-frequency coil 1 as close as possible to the sample, that is, the spinner 2.
consists of a middle tube 4 and a rotor 5, and has a sample filling section 6 inside.

Also, inside the stator 5 is an air blowing lower.

8.9 is provided, and air is blown against the conical side surface of the rotor 5 by sending air in the direction of the arrow in Figure 2 using a compressor or the like.

3, 4, and 5 show a side view, a plan view, and a sectional view of the conical portion of the rotor 5, respectively, and a cross-sectional view of the section A-A in FIG. The conical portion (41) of the rotor is provided with many small grooves 10 that serve as blades. By blowing air into this groove, the sweater 5 or spinner 2 shown in FIG. 2 rotates at high speed. The rotation speed can be changed by adjusting the air pressure.

The size of the spinner cannot be made too large in order to maintain the uniformity of the magnetic field applied to the sample, and the outer diameter of the rotor body is usually about 7 to 101 m. In order to eliminate this, it is necessary to pre-process the rotor with high precision (-g-0~'10 (7) precision 1[)t' starting with the grooves mentioned above. Plastic materials that are easy to process, such as polyacetal, polycarbonate, and polymethyl methacrylate (PMM), have been used.

Note that metal materials such as aluminum that are not ferromagnetic cannot be used as materials for the rotor or camp because they disturb the static magnetic field applied to the sample.

However, in the conventionally used spinner made of the plastic rotor, the plastic itself has C1m nuclei, so an NMR spectrum attributed to the spinner is observed. In other words, the NMR spectrum obtained by packing a sample into a spinner and performing magic angle spinning is the absorption spectrum by the spinner <1&hylf
Since the sample contains a land spectrum (referred to as a land spectrum), the original spectrum of the sample is hidden by the background spectrum, making the analysis of the spectrum inaccurate and inaccurate. Usually, from the observed spectrum, it is determined that the sample is not packed or the NMRg
& Analysis is performed by subtracting the spectrum of a spinner packed with another sample with no yield.

However, even with the same spinner, the spectrum observed will vary depending on the measurement due to slight differences in the spinner's rotational speed or magnetic field, so there is no guarantee that the difference spectrum described above is the spectrum of the material itself.

The subtraction operation also increases the noise level in the spectrum.

Also, conventionally? 7 When using a rustic spinner,
In order to improve the accuracy of the analysis even a little, the background spectrum generated by the spinner must be made as simple as possible, that is, it must have as few peaks as possible. In other words, it is necessary to eliminate the peak splitting caused by spin coupling between C1 and H (prosyn).
Therefore, 1. Deuterated plastic, in which the protons in the plastic are replaced with deuterium that does not cause spin coupling, is usually used as the material for the rotor. This material is very expensive, and the conventional spinner made from it is also expensive.The object of the present invention is to overcome the drawbacks of the prior art described above.
An object of the present invention is to provide a spinner for magic angle spinning of a nuclear magnetic resonance apparatus, which has an inexpensive fi stage and can obtain a C1, NMR spectrum of a solid sample without a puncture ground spectrum caused by the spinner.

In the present invention, the background spectrum caused by the spinner is removed by making the rotor from ceramics or glass ceramics. As mentioned above, the rotor requires precision processing, and boron nitride (BN) is a ceramic that can be used in the present invention.
) with a weight of 50 to 96, and ceramics other than boron nitride.
Oorning Glass V%brks IUSA)
There is a glass ceramic containing synthetic mica microcrystals known as In addition, the product name LOTEC-T (Asahi Glass (
It is possible to use ceramics or glass ceramics in general that can be precisely machined, such as AI, O, .Tie, and sintered bodies known from Co., Ltd.).

In the boron nitride sintered body described above, if the BN content is less than 50% by weight, the machinability of the material is poor and a practical rotor with a desired shape cannot be manufactured. If it exceeds 96% by weight, the strength of the material decreases and the rotor breaks during spinner rotation, making it impractical.

Furthermore, when using a material with a hard surface such as Makor or LOTBC2T, the coil may be worn out when the side surface of the rotor comes into contact with the receiving high-frequency coil during spinner rotation. It is desirable to coat the fluororesin with the following thickness. Strictly speaking, since Cu is present in Teflon, it is thought that if a fluororesin coating is used, a bank ground spectrum due to a spinner will be produced, but if the coating thickness is 40μ or less, the spectral intensity due to Teflon will be is weak and on the same level as the noise level, and the background spectrum due to the spinner is virtually
Although not measured, a thickness of 5 to 40 caps is preferred. Fluororesin coatings that can be used in the present invention include polytetrafluoroethylene and its copolymers such as polyethylene, polychlorotrifluoroethylene and its copolymers with polyethylene, etc., and tetrafluoroethylene-hexafluoropropylene copolymers. This is a general type of coating that uses a series of fluororesins such as polymers.

In the present invention, it is preferable that the material of the cap be the same as that of the rotor, but if the cap 4 is exposed outside the receiving high-frequency coil 1 as shown in Fig. 2, the effect of absorption by the cap will be relatively small, so a plastic material such as Teflon may be used. Use MoJL.

The present invention will be explained below based on specific examples. The second row of the table,
An attempt was made to create a spinner using the rotor material and cap material shown in the fifth row.The materials used are commercially available materials that are easy to use.

The rotor materials of concrete examples AI, A2, A5, A4, and A5 are grade R, HC, 8, and UA-1 of Denka boron nitride molded bodies manufactured by Tokyo Denki Kagaku Kogyo, respectively.
, UA-2, and the rotor material of Mu8 corresponds to the Makor.

The shapes of the cap and rotor are as shown in Figures 2 to 5 above, and are the same as the conventional product. As a result of processing the rotor using a precision locking and milling machine, the shape of the rotor is as shown in the table. ~A4 and A7~A10 rotor materials could be precision machined using carbide tools or 8KH tools, and the A5 rotor could be precision machined using diamond machining, making it possible to create a rotor of the desired shape.

However, in any method, the rotor material of A6, which is not within the scope of the present invention, cracks or breaks in the material during processing, making it impossible to manufacture a rotor of the desired shape. The rotors of A7 and M10 were coated with Teflon coating of 20-30 μm thickness to prevent the receiving high-frequency coil from wearing out.

A spinner is constructed from the created rotor and cap, and the first
The spinner was placed on the stator in the same manner as shown in the figure, and the spinner was rotated without filling the sample.

The spinner was rotated using air pressure as in the conventional case.

The maximum rotational speed and life of each rotor showed good values as shown in the table. The NMR spectra obtained by the spinner at that time were all below the noise level and were virtually unobservable.

In addition, when we examined the state of wear on the receiving high-frequency coils after rotating for a cumulative 50 hours, we found that A5, A8, and Ya9 were worn and needed to be replaced, but the other coils were not worn. There was no need to replace the filter. Here, 7fL1~A
With a rotor made of a material with a high BN content like No. 4, there is no wear on the coils even without Teflon coating. This is because when the BN content is high, the material becomes soft and the rotor body wears out instead of the coil.

This rotor wear will shorten the life of the rotor. However, when the coils become worn out, the rotor itself is less likely to wear out because replacing the rotor is easy and instantaneous, compared to having to redo the time-consuming maintenance operation after replacing the coil. It is not an obstacle.

Next, a solid sample was placed in a spinner and an NMR spectrum was measured. Sample 0, which shows the implementation results of the present invention, used coal powder, and a Fourier transform high-resolution NMR apparatus manufactured by Brucker, USA was used as the NMR apparatus. Spinner is table & 4
Magic angle spinning was performed at s,ooo to 4e000 Hz using the same.

The obtained C, NMR spectrum F is shown in FIG. 6th
The horizontal axis of the figure is the chemical shift δ corresponding to the high frequency frequency, and the vertical axis corresponds to the high frequency absorption intensity. As is well known, the value of chemical shift varies depending on the type of atomic group bonded to the Css nucleus. Therefore, the relationship between the chemical shift and the type of atomic group is determined using a standard sample whose molecular structure is known in advance. By doing so, each peak in the spectrum can be assigned to a specific atomic group, as shown in FIG. 6, and knowledge about the molecular structure of the sample can be obtained.

That is, the coal measured here contains CHs.

÷(-Hl +11 aliphatic carbon atom bonded to hydrogen and carbon, -〇-CH,, l(, -OH,
An aliphatic carbon atom bonded to oxygen such as C-0-C, an aromatic carbon atom (Ar-H) at the ortho position from a substituent [)H or OR, an alkyl group, a naphthene ring, or an aromatic ring bonded to Aromatic carbon atoms (Ar -C), aromatic carbon atoms bonded to @ atoms (Ar-OR, Ar-0H), carbonyl carbon atoms of carboxyl and lactone type (-C=
It was revealed that it contains O), OH, +) and aldehyde-type carbonyl carbon atoms (C=O). In addition,
Here, R is an alkyl group.

Ar represents an allyl group.

On the other hand, FIG. 7 shows a C NMR spectrum obtained by packing the same sample into a conventional spinner consisting of deuterated PMMA glue and a cap. Other than that, the measuring device and measurement conditions are the same as in the case of FIG. 6.

Comparing FIG. 7 and FIG. 6, the number of peaks in FIG. 7 is greater, and the noise in FIG. 7 is also greater.

Figure 8 shows the spinner itself made of deuterated PMMA. N
This is an MR spectrum, and from this it can be seen that the peaks marked with * in FIG. 7 are clearly the background spectrum due to the spinner. This peak is clearly visible in Figure 6 at approximately 209. -C near pm
The peak corresponding to H, cannot be distinguished from noise in FIG.

Further, although the peak value corresponding to C=0 near 200 ppm is clear in FIG. 6, it cannot be distinguished from noise in FIG.

In this way, more information about the chemical structure of the sample coal was obtained by the present invention. This information can be useful, for example, in determining which processes are most suitable for gasifying or liquefying coal.

The present invention is, of course, not limited to the analysis of coal as described above, but can be applied to NMR analysis of all industrially important solid substances such as plastics, rubber biopolymers, and organic semiconductors.

In addition, since the spinner according to the present invention does not use any special material, the price is about 100 to 1000 yen compared to the conventional spinner made of deuterated PMMA, and from an economical point of view, solid-state NMR analysis can be easily performed. Note that the structure of the spinner in the present invention is not limited to the structure shown in the embodiments; for example, the cap part as shown in FIG. 9 also has a groove that serves as a W root.
A spinner consisting of a flangeless rotor 11 and a bladed cap 12 that are rotated between stators from above and below, etc.
All hitherto known spinner structures are applicable to the present invention.

Furthermore, the spinner according to the present invention has the effect of making the rotation speed more even during high-speed rotation than conventional spinners, and making the peak sharper. This uses ceramics or glass ceramics, which have a specific gravity approximately twice as high as the plastics such as PMMA that are the materials of conventional spinners, so they have a large moment of inertia during rotation and are stable even when air pressure fluctuates. This is because it rotates.

As described above, according to the present invention, c of a sharp solid sample with no background spectrum caused by a spinner,
, NMR spectra can be obtained at low cost, and can be used to determine the chemical structure of various solid samples or between molecules in solid samples.
This is a major contribution to clarifying intramolecular interactions.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a magic angle spinning device for NMR, Fig. 2 is a vertical cross-sectional view of the spinner and stator shown in Fig. 1, Fig. 3 is a side view of the rotor canopy shown in Fig. 2, and Fig. 4 is a diagram showing a magic angle spinning device for NMR.
The figure is a plan view of the bulk part of the rotor in Figure 2, viewed from below, and
The figure is an A-All cross-sectional view of Figure 4, Figure 6 is a diagram showing an example of the NMR spectrum of coal sampled using the spinner according to the present invention, and Figure 7 is a diagram showing an example of the NMR spectrum of coal sampled using the conventional 1-last tenk spinner. FIG. 8 is an NMR spectrum diagram of coal, FIG. 8 is an NMR spectrum diagram of a plastic spinner, and FIG. 9 is a diagram showing a spinner having a different shape from that shown in FIG. 1. 2...Spinner, 4...Cap, 5...
・Rota・Representative Patent Attorney Usui 1) Toshiyuki fl Close''')= 2 Figure ``i3WJ t 6 Figure -ct-tz- &(rrm> 9ffi Continued from page 1 0 Author: Arata Uematsu - City of Yokohama 292 Yoshida-cho, Totsuka-ku Hitachi, Ltd. Production Technology Laboratory Author: Masahiro Hatano 2-1-1 Katahira, Sendai City Author Yoshinori Nozawa 2-1-1 Katahira, Sendai City

Claims (1)

Claims: t. A spinner for a nuclear magnetic resonance apparatus, characterized in that at least the rotor is made of ceramics or glass ceramics. 2. At least the rotor is made of ceramics or glass ceramics, and its surface has a thickness of 40 g.
A spinner for a nuclear magnetic resonance apparatus, characterized in that it is provided with an n or less fluororesin film. 5. Ceramics have boron nitride 5θ~96 weight 1
Ceramics other than 1% and boron nitride 4
It is a sintered body made of heavy weight glass ceramics containing synthetic mica microcrystals, or AI, 0.・T
Spinner 0 for a nuclear magnetic resonance apparatus according to claim 1 or 2, characterized in that the spinner 0 is a sintered body of