JPH0943252A - Liquid injection unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately realize and stabilize the injection of a desired volume of liquid by excluding the influence of the final liquid droplet remaining at the end of a needle. SOLUTION: The liquid injection unit comprises gas diffusing means 3 having a gas outlet 3a arranged near the end 1a of a needle for injecting liquid. After the liquid is discharged, the final liquid droplet remaining at the end 1a is diffused down by the pressure of the gas diffused from the outlet 3a and integrated with the injected liquid. Accordingly, the accurately injection of the liquid can be realized without irregularity in the injection volume due to the volume of the final liquid droplet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid injection device for highly accurately controlling the volume of a desired volume of liquid and injecting it into a container or the like.

[0002]

2. Description of the Related Art There is a strong demand in any field to realize a technique for precisely controlling the volume of a liquid and injecting it into another container.
For example, in the preparation of various chemicals, it is necessary to strictly control the volume of each component, and in the preparation of various fragrances and pigments, a very small amount of change in volume greatly affects the quality. Further, in recent years, the accuracy of the detection side of various analyzers has been improved, and high accuracy has also been required for pretreatment and adjustment of various samples and reagents to the analyzer.

Generally, in such a liquid injecting apparatus which requires high accuracy, it is preferable that the tip end portion is formed in a tapered shape in order to ensure accurate measurement, and a hollow needle-like needle is often used. The needle is composed of a pressure adjusting means such as a syringe connected to the needle with a thin tube, and after the tip of the needle is submerged below the liquid surface of the liquid to be measured, the inside of the needle is depressurized / pressurized to obtain a desired volume of liquid. Is designed to be metered in and out.

[0004]

However, in the above-described metering and injecting device, the injection amount is made accurate by precisely controlling the stroke amount of the syringe, but when the injection is completed, the needle tip portion is filled with the liquid. The final droplet often remains due to the surface tension, and the injecting amount varies depending on whether or not the final droplet is dropped.

The volume of the final droplet is usually about 20 μl, and if the total injection amount is 2 ml, a volume error of about 1% occurs. For example, in pretreatment of a liquid chromatograph or addition of an internal standard solution, if there is a volume error of 1%, the CV value of measurement accuracy will increase by one digit, and the degree of variation will be reflected as it is in the analysis result, The reliability is greatly impaired. Further, when a volume error occurs in the amount of the reagent injected in the pretreatment such as spectroscopic analysis, the absorbance of UV or the like or the fluorescence emission amount also largely changes, and the accuracy of the measurement result is deteriorated. Furthermore, even in the case where the amount of sample is extremely small in clinical tests and the like, there is a circumstance in which even one drop cannot be wasted sample.

In order to eliminate such inconveniences caused by the remaining of the final droplet, there are some devices in which the shape and material of the tip of the needle are devised, but the shape and material do not work depending on the liquid quality, and the type of injected liquid is changed. As a result, the needles need to be replaced with new ones because of the cost and labor required to make the needles, and the labor required to replace the needles.

The present invention has been made in order to solve the above problems, and has a simple structure, which makes it possible to surely drop the final liquid droplets regardless of the type of liquid, and to provide a highly accurate injection volume. It is an object to provide a liquid injection device that can be controlled.

[0008]

In order to solve the above problems, in the liquid injecting apparatus according to the present invention, a gas blowing means for directly blowing a gas to the tip of the liquid injecting means such as a needle is provided. It is characterized in that it is arranged near the section.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a liquid injection device to which the present invention is applied. The liquid injecting device is roughly divided into a liquid injecting means 1, a pressure adjusting means 2 and a gas blowing means 3 connected to the liquid injecting means 1.

The liquid injecting means 1 is composed of, for example, a hollow needle-like needle (hereinafter referred to as the needle 1), and is connected to the pressure adjusting means 2 with a thin tube 4 depending on the arrangement and the like. As the pressure adjusting means 2, for example, a microsyringe or the like is used (hereinafter, referred to as a liquid delivery syringe 2). The tip 1a of the needle 1 is immersed in a liquid to be transferred (not shown) such as a reagent in a reagent bottle. After submersion, the inside of the needle 1 is decompressed by the stroke of the liquid delivery syringe 2 to suck a desired volume of liquid to be transferred. After the suction, the needle tip portion 1a is moved to the opening portion of the liquid transfer destination container by automatic moving means such as a robot hand or manually, and the liquid transfer syringe 2 is stroked in the opposite direction to transfer the sucked liquid to be transferred. Discharge. The final droplet remains at the needle tip 1a after the completion of the ejection operation.

In the present invention, such a liquid injection means 1 is provided with a gas spraying means 3. The gas blowing means 3 has a gas blowing port 3a arranged in the vicinity of the needle tip 1a connected to the pneumatic syringe 3b with a thin tube 5 as necessary. The thin tube 5 is provided with a valve as needed. After the liquid injection means 1 completes the liquid discharge, the stroke of the air feeding syringe 3b causes a gas such as air to flow from the gas outlet 3a into the needle tip 1a.
The final droplet remaining on the tip end portion 1a is completely dropped by spraying on. As a result, highly accurate injection can be realized without causing an error in the liquid injection volume due to the final droplet amount.

As the liquid injection means 1, a needle has been taken as an example here, but any means may be used as long as it adopts a tapered shape so that the liquid can be measured, and it is particularly limited to the needle (the whole needle shape). Not something.

As the pressure adjusting means 2 in the needle 1, the microsyringe 2 is adopted here, but various pumps or the like may be used. However, it must have a high ejection accuracy to the extent that the final droplet becomes a problem during measurement.

As the gas spraying means 3, in FIG. 1, the outlet 3a is shown to be provided above the needle tip 1a, but in short, the gas blown out from the outlet 3a remains at the needle tip 1a. It does not have to be limited to FIG. 1 as long as it acts directly on the liquid droplets and the blown-down liquid droplets are arranged at the position where they are dropped onto the container or the like of the transfer destination.

Further, although the pneumatic syringe 3b is adopted as the means for supplying the gas to be sprayed, other public pneumatic means or a pressurized gas cylinder may be connected through a control valve to provide an alternative structure. is there. Further, a mechanism for generating compressed gas by moving the needle 1 may be provided and the compressed gas generated by this may be used for blowing off the final droplets.

As shown in FIG. 2, the stroke of the pneumatic syringe 3b may be synchronized with or connected to the stroke of the liquid syringe 2 to drive them simultaneously. The thin tube 5 is provided with a valve as needed. With such a configuration, even when a screw feed mechanism that is commonly used is adopted as the drive mechanism of the syringe, a phenomenon called backlash due to the margin interval of the screw groove is a direction in which compressed air pushes back to the syringe. Since the force is applied, it is possible to avoid the phenomenon that the injection amount deviates from the stroke amount.

Although the discharge capacities of the liquid delivery syringe 2 and the pneumatic delivery syringe 3b are simply expressed as equivalent in the figure, the stroke distance and the inner diameter can be appropriately selected so as to obtain the required pressure delivery volume. Good.

As the type of gas to be blown, air can be used simply, but another gas that does not cause any inconvenience in the quality of the liquid to be transferred may be used. When the liquid to be transferred is highly volatile, a mechanism for cooling the gas to be sprayed may be additionally provided.

The timing of blowing the gas is not particularly limited. In short, if the final liquid droplet does not remain, the purpose of achieving accuracy in the injection volume is achieved, and as described above, the pneumatic syringe 3b is driven simultaneously with the stroke of the liquid transport syringe 2 in synchronization or connection. Then, the gas may be blown to the needle tip 1a at the same time as the liquid is ejected so that the final droplets do not remain, or the final droplets may be blown off after the ejection is completed. A valve may be provided in the thin tube 5 if necessary.

[0021]

EXAMPLE As another configuration example of the liquid injection apparatus according to the present invention, as shown in FIG. 3, the needle tip portion 1a and the gas outlet 3a are formed in a double pipe. The arrow in the figure indicates the flow of gas blown from the outlet 3a toward the needle tip 1a. With such a configuration, the liquid transfer destination container can be suitably operated even when the opening is narrow, and even when the liquid transfer destination container is used for a long period of time, the tip portion 1a and the gas outlet 3a are not separated. There is no deviation in the positional relationship.

[0022]

According to the sample injection device of the present invention, the final liquid droplet can be surely dropped with a simple structure regardless of the type of liquid, and the injection volume can be controlled with high accuracy. . Further, since the injection volume is stable even after repeated injections, the reproducibility of analysis results and the like is good, and the quality of the product prepared by mixing various liquids is improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a sample injection device according to the present invention.

FIG. 2 is a diagram showing another configuration example of the sample injection device according to the present invention.

FIG. 3 is a diagram showing another configuration example of the sample injection device according to the present invention.

[Explanation of symbols]

 1 ... Liquid injection means (needle) 1a ... Tip of needle 2 ... Pressure adjustment means (liquid delivery syringe) 3 ... Gas Spraying means 3a ... Gas outlet 3b ... Air-injection syringe 4,5

Claims (1)

[Claims] 1. A liquid injecting device, which comprises a liquid injecting means having a tapered tip and a pressure adjusting means for pressurizing and depressurizing the liquid injecting means, for metering and discharging a desired volume of liquid. And a gas injection unit for directly spraying a gas onto the tip of the liquid injection unit.