JP4254848B2 - Sample cooling device - Google Patents

Description

  The present invention relates to an analyzer that automatically analyzes a liquid sample, for example, and more particularly to a sample cooling device that cools a sample before analysis in a liquid chromatograph.

  In automatic analysis in a liquid chromatograph, a sample container filled with a small amount of sample is mounted on a rack, this rack is set in an automatic sample injection device, and the automatic sample injection device starts from the sample container on this rack according to a predetermined program. This is performed by sequentially sucking up the sample and injecting it into the liquid chromatograph. Samples on the rack that are waiting for analysis are often placed at room temperature, but some samples may need to be kept at a low temperature to prevent alteration. In such a case, an apparatus used for the purpose of cooling the sample is a sample cooling apparatus.

  There are two types of conventional sample cooling devices, a direct cooling type and an air cooling type. In the direct cooling method, a rack is made of a metal having good heat conductivity, a cooler (such as a Peltier element) is attached to the bottom of the rack, and the temperature of the sample is adjusted mainly by heat conduction through a solid. In the air-cooling method, the main part of an automatic sample injection device including a rack is surrounded by a heat insulating case, the air inside is cooled, and the temperature of the sample is adjusted via the air. Next, the direct cooling method according to the present invention will be described in more detail with reference to the drawings.

  FIG. 2 shows an example of a conventional direct cooling type sample cooling apparatus. The analyst first puts the liquid sample 4 in a sample container (usually a glass vial) 2 and seals the mouth with a septum 3, which is mounted on the rack 1 removed from the automatic sample injection device 7. . The rack 1 is made of aluminum and has about 100 holes 5 into which the sample containers 2 are inserted. Heat is transmitted to the sample container 2 through the bottom of the hole 5 and the surrounding wall (hereinafter, simply referred to as heat includes cold heat).

  The rack 1 after loading the sample is set on the metal block 23 in the apparatus. The metal block 23 is a heat transfer member configured to be cooled by a cooler (Peltier element 21) attached to the lower surface, and to keep good heat conduction with its surface in close contact with the bottom of the rack 1. In this case, the rack 1 also functions as a heat transfer member that transfers the heat received from the metal block 23 to the sample container 2. The Peltier element 21 is controlled by a temperature control device (not shown) to cool the metal block 23 to a predetermined temperature on its heat absorption surface, and on its back surface (heat radiation surface), the heat radiation fins 22 face the inside of the ventilation duct 27. The heat absorbed from the metal block 23 is radiated by the air blown by the fan 28 through the heat radiating fins 22.

  With such a configuration, the rack 1, the sample container 2 mounted on the rack 1, and the sample liquid 4 therein are kept at a predetermined low temperature. The rack 1 is covered with a heat-insulating cover 6 for cold insulation, but the head of the sample container 2 (the septum 3 and its surroundings) is exposed from the cover 6 so that the sample can be taken out by the sampling needle 13. , Exposed to room temperature air.

  The sampling needle 13 can be moved back and forth, left and right, and up and down by a mechanism (not shown). According to the program, the sampling needle 13 pierces the septum 3 and sucks the liquid sample 4 from the sample container 2 and moves to the sample inlet 12 of the liquid chromatograph. Automatic analysis is performed by injecting a sample into the tube. Since the analysis of the liquid chromatograph requires one time enough, the sample on the rack 1 is long and is in a state of waiting for analysis for several tens of hours. During this time, the sample is prevented from being altered by being kept at a low temperature.

  The above-described conventional direct cooling type sample cooling apparatus has high heat transfer efficiency and can cool to a predetermined temperature in a short time. As described above, the head of the sample container 2 is exposed to air at room temperature. Since the rack is cooled mainly from the bottom, the sample container is likely to be in a state where the bottom is cold and the top is warm, that is, temperature unevenness occurs. Moreover, since convection does not occur because the temperature is low in the lower part, the temperature unevenness does not disappear even after a lapse of time and tends to persist.

  If the sample container has temperature unevenness, the sample liquid in the container may have concentration unevenness. If sampling is performed in such a state, the analysis result may vary. This invention is made | formed in view of such a situation, and it aims at providing the sample cooling device which does not produce the above temperature nonuniformity easily.

  In order to solve the above-described problems, the present invention provides a sample cooling apparatus that includes at least a rack and a cooler, and cools a liquid sample in a sample container mounted on the rack by the cooler to room temperature or lower. The rack is provided with a plurality of holes so that the sample container is mounted, and the inner diameter of the hole adjacent to the bottom of the sample container is larger than the upper inner diameter when the sample container is mounted. And a heat insulating member is laid at the bottom of the hole.

  With this configuration, the sample container is mainly cooled by heat transfer from the upper part of the side surface, and is not rapidly cooled from the bottom surface, thereby preventing temperature unevenness between the upper and lower sides in the sample container. it can.

  The rack of the sample cooling device according to the present invention is configured so that the inner diameter of the portion close to the bottom of the sample container is larger than the upper inner diameter when the sample container is mounted. It is cooled by heat transfer through the top of the side wall and is not cooled strongly from the bottom. Therefore, since convection is likely to occur, temperature unevenness is unlikely to occur in the liquid in the sample container. As a result, density unevenness based on the temperature difference is suppressed, and the reproducibility of the analysis is improved.

  One embodiment of the present invention is shown in FIG. In FIG. 1, only the main parts such as a rack and a sample container are shown in an enlarged manner, and the others are omitted because they are the same as those in FIG. The rack 51 is made of aluminum and has about 100 holes 55 into which the sample containers 2 are inserted. A disc 35 is laid at the bottom of the hole 55. The presence of the disk 35 suppresses rapid cooling from the bottom of the sample container 2, and therefore, it is possible to suppress the occurrence of uneven temperature between the upper and lower sides in the sample container as seen in the conventional apparatus. . As the material of the disc 35, a material having high heat insulation and excellent chemical resistance is prepared in case a sample leaks. Specific examples include foamed polyethylene and the like.

  Furthermore, the hole 55 has a larger inner diameter near the bottom than the upper inner diameter. For this reason, the sample container 2 is cooled mainly by heat transfer from the upper side wall. Not only the heat transfer from the bottom surface of the sample container due to the action of the disc 35 is suppressed, but also the heat transfer from the portion close to the bottom of the side wall is suppressed, and convection easily occurs, so the effect of suppressing temperature unevenness is further improved. To do.

  In addition, this invention is not limited to the numerical value and material name which were illustrated in the said description, Moreover, the embodiment is not limited to said Example. For example, the metal block 23 which is a heat transfer member may be omitted and the cooler may be directly attached to the lower part or the side part of the heat transfer member of the rack 1.

It is a figure which shows one Example of this invention. It is a figure which shows the principal part of the conventional sample cooling device.

Explanation of symbols

1, 51 ... Rack 2 ... Sample container 3 ... Septum 4 ... Liquid sample 5, 55 ... Hole 6 ... Cover 7 ... Automatic sample Injection device 12 ... Sample injection port 13 ... Sampling needle 21 ... Peltier element 22 ... Radiation fin 23 ... Metal block 27 ... Ventilation Duct 28 ... Fan 31 ... Metal plate 35 ... Disc

Claims (1)

  In a sample cooling apparatus that includes at least a rack and a cooler, and cools the liquid sample in the sample container mounted on the rack to the room temperature or lower by the cooler, the sample container is mounted on the rack. A plurality of holes are drilled in the hole, and the hole is drilled so that when the sample container is mounted, the inner diameter of the portion adjacent to the bottom of the sample container is larger than the upper inner diameter. Is a sample cooling device in which a heat insulating member is laid.

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