JPH1172421A - Sampling apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat conduction efficiency and enhance accuracy in temperature control to a sample on the occasion of sampling, by filling a heat medium liquid into a hole of a metallic, heat-retaining block controlled at a predetermined temperature to which a sample bottle is inserted. SOLUTION: An automatic head space sampling apparatus 10 of, e.g. a gas chromatograph is provided with a metallic heat-retaining block 18 which has a hole 18H to which a sample bottle 19 is to be fitted and is heated to a predetermined temperature by a plane heater 24 or the like. An inner diameter of the hole 18H is slightly larger than an outer diameter of the sample bottle 19. An oil A of a small amount which has suitable thermal conductivity, viscosity and heat resistance corresponding to a heating temperature is filled as a heat medium liquid at a bottom of the block. Water can be used if the heating temperature is not higher than approximately 60 deg.C. When the sample bottle 19 having an analysis sample sealed therein is inserted in the hole 18H, a level of the oil A is raised thereby filling a gap, whereby an excessive oil A overflows to be collected. After a predetermined time, the analysis sample is sampled with the use of a cylinder 11 or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for sampling a sample by heating and keeping a sample at a predetermined temperature in an analyzer such as a gas chromatograph.

[0002]

2. Description of the Related Art One of the analytical methods of gas chromatography is a headspace gas analyzing method. In this method, a liquid or solid sample is sealed in a sample bottle with a septum lid while leaving a small space at the top, and is kept at a predetermined temperature for a predetermined time. By collecting and analyzing with a syringe, the volatile components in the sample are qualitatively or quantitatively determined. What is important in the headspace analysis method is the temperature control during the pretreatment heat keeping. If the temperature varies, sufficient reproducibility of the analysis result cannot be obtained.

Conventionally, a dry bath (or block bus) is often used as a means for heating and keeping a sample bottle warm.
It is called. In this method, a plurality of holes having an inner diameter slightly larger than the diameter of the sample bottle are formed in a metal heat retaining block heated by an electric heater, and the sample bottle is inserted into the holes to keep the temperature. If you use an appropriate temperature controller, it can be automatically adjusted to any temperature, and it uses a metal block with good heat conduction, so there is little temperature unevenness.The whole structure is simple and easy to handle. It is also relatively easy to construct this block itself to be mechanically moved by incorporating the block into the block.

[0004] As another means, a wet bath system (liquid bath system) may be used. In this method, the sample is kept warm by immersing the sample bottle in a heated liquid tank. Since the heat transfer is good, the sample is quickly and uniformly heated.

[0005]

In the conventional dry bath method for heating and keeping a sample bottle warm, there are some distances between the heat retaining block and the bottle in consideration of the variation in the outer diameter of the sample bottle and the ease of inserting and removing the bottle. A gap is needed. as a result,
Adhesion is poor, and heat is transmitted only by a small amount of conduction from the contact portion and radiation from the inner wall of the block, so that the heat transfer efficiency is low and it is difficult to effectively control the temperature. In other words, even if the heat retaining block is uniformly heated to the predetermined temperature, not all the inserted bottles are maintained at the predetermined temperature, and this point is a serious problem in an analysis that emphasizes reproducibility. Become.

On the other hand, in the wet bath system in which heat is kept warm, there is no problem with respect to heat transfer. However, in order to increase the temperature control accuracy, a device for circulating or stirring the liquid and a liquid for coping with evaporation loss of the liquid are used. Auxiliary equipment for volume control, and a structure that guards surrounding machinery and equipment from leaks and splashes of liquid are required, and the overall structure is complicated, so it is not suitable for obtaining automated equipment compactly. there were.

As described above, the present invention provides a sampling device including a sample bottle heat retaining device having two features, which are incompatible with the conventional method and have a simple structure with good heat transfer and excellent operability. It is intended to provide.

[0008]

In order to achieve the above object,
According to the present invention, a hole for inserting a sample bottle is drilled, and a hole of a metal heat insulating block controlled to a predetermined temperature is filled with a heat medium liquid having a high thermal conductivity. When the sample bottle is inserted with the heat medium liquid filled, the gap between the hole and the inner wall of the hole is filled with the heat medium liquid, heat transfer efficiency is improved, and the temperature of the sample is accurately controlled.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an automatic head space sampling apparatus for a gas chromatograph will be described with reference to FIGS.

FIG. 1 shows an automatic headspace sampling apparatus 10, in which a syringe 11 is fixed just above a sample inlet 21 of a gas chromatograph 20, and is generally controlled by a program controller (not shown). Is controlled. A syringe drive mechanism 15 for moving the syringe 11 up and down, and a plunger 13 of the syringe 11
And a plunger drive mechanism 16 for moving the plunger up and down. Although both of these drive mechanisms are driven by a motor or an air cylinder, their detailed structure is simplified in FIG. 1 and is indicated by a dashed block because it is not directly related to the present invention.

A sample bin 19 containing a sample for analysis is mounted on a metal heat retaining block 18 functioning as a sample holder. The sample bottle 19 has a structure in which the mouth is sealed with a septum made of rubber or soft plastic, and a gas or liquid inside can be taken in and out by penetrating a syringe needle 11S described later into the septum.

As schematically shown in FIG. 2, the heat retaining block 18 has a "C" shape having a notch 18K in a part of the ring, and the heat retaining block 18 is formed around the center of the ring. 180
It is rotated by the sample drive mechanism 17 within a range of degrees. Since the configuration of the sample driving mechanism 17 is not directly related to the present invention, it is simplified in FIG. 1 and is indicated by a dashed block. The heat-retaining block 18 is heated by a planar heater 24 closely fixed to the outer periphery thereof, and is controlled at a predetermined temperature set according to the purpose of analysis by a temperature controller (not shown). The syringe 11 is also heated by the heater jacket 12 to substantially the same temperature as the heat retaining block 18.

In this embodiment, seven holes 18H for mounting sample bottles 19 are provided at intervals of 45 degrees. In general,
Since the pretreatment warming time is longer than the analysis time, a plurality of samples are warmed in parallel for continuous analysis. For this reason, a plurality of holes are required. The inner diameter of the hole 18H is slightly larger than the outer diameter of the sample bottle 19, and the gap is filled with oil A having good heat conductivity. A plastic funnel-shaped collar 14 having appropriate elasticity and heat resistance is fixed to the mouth of each hole.

The automatic headspace sampling apparatus 10 configured as described above operates as follows in accordance with a preset program.

First, a liquid sample to be analyzed (a sample may be a solid, but in the following description, a liquid) is placed in a sample bottle 19.
And inserted into the hole of the heat retaining block 18. Since the bottom of the hole is previously filled with a small amount of oil A as a heat transfer liquid, when the sample bottle 19 is inserted, the liquid level of the oil A rises and fills the gap between the sample bin 19 and the inner wall of the hole. Excess oil A flows down through the overflow pipe 23 and is collected by the oil receiver 22. After a lapse of time for the sample in the sample bottle 19 to reach the gas-liquid equilibrium, the heat retaining block 18 is rotationally driven by the sample driving mechanism 17 and moves until the sample bottle 19 is positioned directly below the syringe 11. Until this time, the syringe 11 has been lifted to the uppermost position immediately after the previous sampling. At this point, the syringe 11 is lowered by the syringe drive mechanism 15, and the needle 11 S penetrates the septum of the sample bottle 19 and the tip end. Is the sample bottle 19
It stops at a position that does not reach the liquid level in the upper space inside. Next, the plunger 1 is driven by the plunger driving mechanism 16.
3 is pulled up, and the gas in the upper space in the sample bottle 19 is sucked into the syringe 11. Syringe 11 is heated block 18
Since the gas is heated to almost the same temperature as that of the syringe 11, the inhaled gas does not cause a phase change in the syringe 11.

Subsequently, the syringe 11 is pulled up by the syringe drive mechanism 15, and the heat retaining block 18 is moved by the sample drive mechanism 17, so that the cutout portion 18K is located immediately below the syringe 11. Then, when the syringe 11 is lowered to the lowest position by the syringe driving mechanism 15, the needle 11S of the syringe 11 is notched 18K.
Through the septum provided above the sample inlet 21. Immediately thereafter, the plunger 13 is pushed down by the plunger drive mechanism 16 and the collected gas is discharged into the sample inlet 21.

Thereafter, by returning the syringe 11 to the highest position by the syringe driving mechanism 15, one cycle of the operation of the automatic headspace sampling apparatus 10 is completed. The sample bin 19 after sampling is taken out of the heat retaining block 18 manually by an operator or the like or by a separately provided robot device or the like, and another sample bin 19 is newly inserted.

The oil A attached to the outer periphery of the sample bottle 19 when the sample bottle 19 is taken out is wiped by the collar 14 to remove the same hole 18H.
Returning inside, the loss of oil A is small, but oil A replenishment is still required. The replenishment may be performed manually by an operator, or may be automatically replenished using an oil pump (not shown) operated by a program. In this case, it is naturally considered that the oil A collected in the oil receiver 22 is recycled.

To wipe off the oil A, instead of the collar 14, a brush-like material or a material made of another material such as metal may be used. The collar 14 also serves to keep the sample bottle 19 at the center of the hole 18H, and to hold the sample bottle 19 with a frictional force so that when the sample amount is small, the oil A
It also plays a role in preventing the sample bin 19 from rising due to buoyancy received from the sample bin 19.

As the oil A as the heat medium liquid, an oil having appropriate heat conductivity and viscosity and heat resistance corresponding to the heating temperature is selected and used. However, if the heating temperature is not more than about 60 degrees Celsius. Water can also be used, and is not limited to oil A.

The present invention can be applied not only to the headspace sampling of the above-described embodiment but also to the case where the sample is sampled at a constant temperature for the purpose of preventing a phase change of the sample. In addition, the analyzer is not limited to the gas chromatograph, but can be widely applied to analyzers based on other principles, and can provide an effect.

[0022]

As described above in detail, according to the sampling apparatus of the present invention, the heat conduction from the heat retaining block to the sample bottle is improved, and the precision of the heat retaining can be improved. Therefore, it is particularly effective in the case where the temperature accuracy at the time of pre-processing and keeping the temperature of the sample directly affects the composition of the sampled gas as in the headspace analysis method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a sampling device of the present invention.

FIG. 2 is a view showing a shape of a heat retaining block in the sampling device of the present invention.

[Explanation of symbols]

 11 Syringe 11S Needle 12 Heater jacket 13 Plunger 14 Color 15 Syringe drive mechanism 16 Plunger drive mechanism 17 Sample drive mechanism 18 Heat insulation block 18H Hole 18K Notch Part 19: Sample bottle 20: Gas chromatograph 21: Sample inlet A: Oil

Claims (1)

[Claims] 1. An apparatus for keeping a sample warm by inserting a sample bottle containing a sample to be analyzed into a hole formed in a metal heat retaining block controlled at a predetermined temperature. A sampling device characterized by being filled with.