JPH0725665Y2 - Organic solvent drying equipment for electron microscope samples - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention holds water for maintaining the morphology of biological tissue when observing a biological sample by an electron microscope, and retains the fine morphology of the tissue of the sample. The present invention relates to an improvement in an organic solvent drying device for removing in a state.

[Prior Art] Since the sample chamber of the electron microscope is kept at a high vacuum, the sample containing water cannot be observed.
However, simply drying causes the sample to shrink and deform. In particular, it is almost impossible for the electron microscopic microstructure to retain its original shape due to the surface tension of water during the drying process. The freeze-drying method has long been used for optical microscope observation. This method freezes the sample to -50
It sublimates water in a vacuum while keeping it at around ℃, and its morphology was tentatively preserved in the range of optical microscope observation.
However, in order to suppress the crystal growth of ice, it is necessary to keep the temperature below -80 ° C. However, at such a low temperature, the sublimation rate of water is extremely slow, and several days are required even in a high vacuum, which is not suitable for practical use.

Recently, as an improved method for freeze-drying, a method has been proposed in which water is replaced with an organic solvent, which is frozen and dried in a vacuum,
It is about to be put to practical use. As the organic solvent, those which are liquid or solid at room temperature and atmospheric pressure and have large vaporization heat with a relatively slow evaporation rate are desirable. For example, Freon 113, acetonitrile, tertiary butanol, benzene, neopentane, etc. are recommended. These liquids are easily solidified by cooling at a temperature sufficiently higher than the freezing temperature in the freeze-drying method or by reducing the pressure. Then, it can be sublimated relatively quickly at a degree of vacuum that can be maintained by a vacuum pump such as an oil rotary pump.

In order to utilize the above-mentioned properties, first, water in biological tissue is dehydrated with acetone or alcohol, which is then replaced with the above-mentioned organic solvent, cooled, solidified and vacuum-exhausted to dry. This method is superior to other conventional drying methods in terms of maintaining fine morphology, and the time required for drying can be shortened to several tens of times in the case of water, and the vacuum exhaust device is a simple oil rotary pump. It has the advantage that it can be done with just one thing.

However, a disadvantage of the above method is that the sublimated organic solvent remains dissolved in the oil of the rotary pump, which lowers the ability as an oil rotary pump, that is, the pumping speed and the degree of vacuum. Therefore, there is a problem that performance and reliability for long-term use are slightly low.

In order to prevent the vaporized organic solvent from being sucked toward the oil rotary pump side, for example, a means of providing a cold trap filled with liquid nitrogen or the like is conceivable.

[Problems to be solved by the invention] However, in the organic solvent freeze-drying method, since the organic solvent is evaporated at a much higher temperature than the water freeze-drying method, a cold trap filled with liquid nitrogen or the like is provided in the vacuum container. When provided, the sample is cooled by the cold trap, so the temperature of the sample drops too much. As a result, the sublimation of the organic solvent becomes extremely slow, and it becomes impossible to quickly sublimate the organic solvent at a low degree of vacuum.

Further, since the cold trap filled with the refrigerant such as liquid nitrogen has the refrigerant container, it cannot be taken out from the vacuum chamber. Therefore, in order to remove the organic solvent adhering to the surface of the cold trap from the inside of the vacuum container after processing the sample, it is necessary to disassemble and wash the entire vacuum chamber. Therefore, it takes a lot of trouble to remove the organic solvent attached to the cold trap. Moreover, since liquid nitrogen has to be taken in and out each time cleaning is performed, the amount of liquid nitrogen consumed is large.

Therefore, in view of the problems of the organic solvent freeze-drying method in the above-mentioned conventional technique, an object of the present invention is to prevent the organic solvent from flowing into the rotary pump without lowering the temperature of the sample more than necessary, and further to cold trap. It is an object of the present invention to provide an organic solvent drying apparatus for an electron microscope sample which can easily remove the organic solvent attached to the sample and consumes less refrigerant such as liquid nitrogen.

[Means for Solving the Problems] That is, the object of the present invention is to store a sample for electron microscope observation in which water is replaced by an organic solvent in the bottom of a cup-shaped sample container having a wall that stands up around the sample. Further, the same sample container is further housed in the vacuum chamber, and a block-shaped low-temperature metal body cooled in advance to a low temperature is arranged in the vicinity of the outside of the peripheral wall of the sample container. It is achieved by an organic solvent drying apparatus for the sample.

[Operation] In the organic solvent drying device according to the present invention, the sample for electron microscope observation in which water is replaced by the organic solvent is stored in the bottom of the cup-shaped sample container having the wall rising up in the periphery, and the sample is placed in the vacuum chamber. Since the low temperature metal body is arranged near the outside of the wall around the sample container, the sample is shielded by the wall against the low temperature metal body, and the sample is not directly cooled by the low temperature metal body. Therefore, the sample temperature does not drop more than necessary, and the organic solvent can be quickly sublimated in a relatively low degree of vacuum.

Furthermore, since the low-temperature metal body is a block that has been cooled in advance, when removing the organic solvent attached to the low-temperature metal body from the vacuum device, the low-temperature metal body alone needs to be taken out from the vacuum chamber. Therefore, the organic solvent attached to the low temperature metal body can be easily removed from the vacuum chamber. Moreover,
It consumes less refrigerant such as liquid nitrogen.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view showing an embodiment of the present invention. It is an example of an experimental simple device for treating a relatively small amount of sample with an organic solvent drying device. 1 is a glass bell for a vacuum chamber, and 2 is a substrate
Together with this, a vacuum chamber is formed. The sample container 4 is placed on the substrate 2 via the heat insulating base 3. The sample container 4 is a cup-shaped one having a wall rising up to the periphery, and a sample 5 in which water is replaced with an organic solvent is put in the bottom surrounded by the wall together with a small amount of the same organic solvent. A block-shaped low-temperature metal body 6 having a large heat capacity, which has been cooled in advance by a coolant such as liquid nitrogen, is placed near the outside of the wall around the sample container 4.

With such a configuration, when the pressure is exhausted from the exhaust pipe 8 on the substrate 2 by the oil rotary pump P, the organic solvent is rapidly evaporated, the heat of vaporization is taken away, and the organic solvent immediately freezes and becomes a solid.
Then, the solidified organic solvent sublimes due to the pressure drop in the vacuum chamber, but there is a cryogenic low temperature metal body 6 in the vicinity thereof, and the vicinity of the surface thereof is at a pressure state much lower than the oil rotary pump P side. Therefore, the evaporated gas of the organic solvent flows toward the low temperature metal body 6 and is adsorbed on the surface of the metal body 6.

That is, the low temperature metal body 6 of −100 ° C. or less creates a vacuum much higher than the vacuum degree by the simple oil rotary pump P in the vicinity of the sample container 4 due to the cold trap effect, and the inside of the sample container 4 is It provides a synergistic effect of promoting sublimation of the organic solvent. Moreover, since the sample 5 is shielded from the low temperature metal body 6 by the wall around the sample container 4 and is not directly cooled, the temperature of the sample 5 does not drop more than necessary. Therefore, the organic solvent of the sample 5 is quickly dried and the drying time is shortened. By the initial evacuation, some of the organic solvent is sucked into the oil rotary pump P before the organic solvent self-freezes. If this is not desired, the organic solvent may be solidified in advance by cold air of liquid nitrogen.

FIG. 2 is a vertical sectional view showing another embodiment of the present invention.
This is an example of a large amount of sample processing device capable of recovering an organic solvent. The low temperature metal body 6 as a cold trap is formed into a cylindrical block shape to increase the adsorption area of the organic solvent,
A cup-shaped sample container 4 is placed in this via a heat insulator 10. Then, the cylindrical low-temperature metal 6 is placed in thermal contact with a metallic disc 7 having a good thermal conductivity, and is placed on the substrate 2 of the vacuum chamber via the thermal insulator 3.

Next, the operation of the embodiment configured as described above will be described. First, the rimmed metal disk 7 with the thermal insulator 10
It is installed on the substrate 2 via the thermal insulator 3. On top of this,
The organic solvent-immersed sample 5 is placed in the bottom of the cup-shaped sample container 4, cooled, solidified, and mounted. Next, the cylindrical low-temperature metal body 6 is brought to the liquid nitrogen temperature, placed so as to surround the sample 5, covered with the vacuum chamber glass bell 1, and evacuated by the oil rotary pump P through the exhaust pipe 8 on the substrate 2. I do.
Then, as the pressure drops, the organic solvent sublimes, but most of the organic gas is adsorbed by the surrounding low temperature wall,
Unadsorbed gas is also adsorbed on the outer wall, and the flow of organic gas to the oil rotary pump side is almost eliminated.

This is the same if the amount of organic solvent is within a certain amount,
The powdery organic solvent is laminated and adsorbed on the low temperature wall, and when it exceeds a certain thickness, it peels off and falls onto the edged disk 7. The edged disk 7 is deprived of heat by the cylindrical low-temperature metal body 6 and has a similar low temperature, so that the powder of the organic solvent that has dropped does not evaporate.

Further, after the drying of the sample 5, the vacuum is broken to remove the glass bell 1 for the vacuum chamber, the sample container 4 is covered, and then the low-temperature metal body 6 is removed. Adsorption can be prevented.

Depending on the type of organic solvent, the heat of vaporization brings the temperature to a considerably low temperature. Therefore, when air is introduced into the vacuum chamber, moisture in the atmosphere is adsorbed by the dried sample 5. When such an organic solvent is used, a small heater 9 is provided on the heat insulation base 10,
The sample container 4 is placed on it. After drying the sample 5, the temperature of the sample may be raised to near room temperature by the heater 9 and then taken out into the atmosphere. The powdery organic solvent adhering to the low-temperature metal body 6 and the rimmed disk 7 is returned to room temperature and recovered.

[Effects of the Invention] As described above, according to the present invention, the organic solvent can be prevented from flowing into the rotary pump without lowering the temperature of the sample more than necessary, so that the sublimation rate of the organic solvent is reduced. Sample can be processed in a short time. Further, it is possible to easily remove the organic solvent attached to the low-temperature metal body, and it is possible to provide an organic solvent drying apparatus for an electron microscope sample that consumes less refrigerant such as liquid nitrogen.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the organic solvent drying apparatus of the present invention, and FIG. 2 is a vertical sectional view showing another embodiment of the present invention. 1 ... Glass bell for vacuum chamber, 2 ... Substrate, 3, 10 ... Thermal insulation stand, 4 ... Sample container, 5 ... Sample, 6 ... Low temperature metal body, P ... Oil rotary pump

Claims (1)

[Scope of utility model registration request] 1. An organic solvent for an electron microscope sample, which is vacuum-dried in a vacuum chamber maintained at a temperature at which it maintains the solid state of the organic solvent of an electron microscope sample in which the water content is replaced by an organic solvent. In the drying device, the bottom of a cup-shaped sample container having a rising wall around the periphery, the sample for electron microscope observation in which water was replaced by an organic solvent was stored, and the same sample container was stored in the vacuum chamber. An organic solvent drying apparatus for a sample for an electron microscope, characterized in that a block-shaped low-temperature metal body cooled in advance to a low temperature is arranged in the vicinity of an outer side of a wall around the sample container.