JP2517363B2 - Repellent treatment near the tip of the pipette - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention forms a water-repellent surface in the vicinity of the tip of a nozzle (discharge pipe) of a quantitative pipette for supplying a fixed amount of sample liquid in chemical analysis. To a method and apparatus useful for

[Prior Art] Recently, a clinical chemistry test by a dry method has been widely used because it is excellent in simplicity of analysis work, speed of measurement and the like. By this dry method, clinical chemistry tests are carried out by spotting a liquid sample on a chemical analysis slide containing a reagent that reacts with a specific component such as glucose and urea nitrogen (BUN) in a liquid sample such as blood, which is the sample. The specific component is quantified by colorimetrically analyzing the color development, discoloration, etc. generated by the reaction of the specific component.

Conventionally, in order to spot a sample (sample solution) on a chemical analysis slide, after inhaling a predetermined amount of the sample with a pipette, a round droplet of the sample is formed at the tip of the pipette, and this droplet is placed in the center of the chemical analysis slide. I was wearing them by touching them gently.

In such a spotting method for a sample, there are large individual differences in spotting accuracy, and it has been difficult to obtain satisfactory inspection accuracy. The main causes of this individual difference are that it is difficult to keep the relative positional relationship between the tip of the pipette (of the nozzle) and the spotting surface of the chemical analysis slide constant, and that after the liquid is sucked, It was often the case that droplets were not formed unless the adhering liquid was wiped off.

One way to eliminate individual differences in spotting is to mount a pipette on a gantry and manually or automatically discharge the liquid from the pipette. However, in this case, since the distance between the tip of the pipette and the spotting surface of the chemical analysis slide is constant, form a droplet on the tip of the nozzle of the pipette, and then contact the chemical analysis slide for spotting. I can't.

There are various sample liquids to be tested on the chemical analysis slide, such as whole blood, plasma, serum, diluted solutions thereof, urine, saliva, etc., and the viscosity is different, so the liquid receiving surface of the chemical analysis slide (usually the spreading layer) The speed of absorption is different. Also, different types of analytical slides are used depending on the components to be detected,
Even with the same type of sample liquid, the rate of absorption on the liquid receiving surface (usually the spreading layer) differs depending on the type of chemical analysis slide. If the ejection speed from the pipette is too fast with respect to the speed absorbed by the chemical analysis slide, a part of the liquid droplet adheres to and remains around the tip of the nozzle, resulting in an error in the amount of spotted liquid. That is, the amount of liquid to be supplied becomes insufficient in the spotting that causes the adhesion, and the liquids that have previously adhered merge in the subsequent spotting, which causes a positive (+) error in the liquid amount.

In order to prevent the liquid droplets from adhering to the outer surface of the tube near the tip of the nozzle, it has been considered that only the outer side of the nozzle is made of a water-repellent material. However, the double structure of the nozzle complicates the manufacturing process of the nozzle and increases the cost.

Also, it takes time and effort to wipe off the liquid adhering to the outside of the tip of the nozzle each time liquid is sucked, and if care is not taken, it may be forgotten, resulting in an error in the amount of liquid.

[Technical Problem to be Solved] The present invention provides a pipette used in analysis, which discharges a certain amount of liquid from the tip of a nozzle (discharge tube) once or repeatedly, to the outside of the vicinity of the tip of the nozzle. Quantitative so that stable liquid droplets can be formed without part of the liquid adhering and the sample liquid does not drop from the pipette under its own weight, and can be dropped once or repeatedly with high liquid volume accuracy. A method for forming a water repellent surface on the outer surface near the tip of a pipette nozzle, and an apparatus used to practice the method.

[Means for Solving the Technical Problem] One of the above-mentioned problems of the present invention is to have a liquid retaining property 2
The liquid holding surface of one of the two members is made to hold the liquid having the property of imparting water repellency, and at least part of the range of 0.3 to 10 mm from the tip of the pipette is brought into contact with the liquid holding surface of the two members. , Solved by a method of forming a water repellent surface on the outer surface of this part of the pipette.

Another one of the above-mentioned problems of the present invention is a pipette and two members which have a liquid-retaining surface and hold a liquid having a property of imparting water repellency to the liquid-retaining surface. 0 from the tip.
Means for holding the pipette such that the pipette rotates between these two surfaces while simultaneously contacting at least a portion of the range 3-10 mm with the liquid-retaining surfaces of said two members;
Means for moving the two members so that the liquid-retaining surfaces of the two members move in opposite directions along the surfaces. 0.3 from the tip of the pipette.
Solved by a device that creates a water repellent surface on the outer surface within a range of ~ 10 mm.

The pipette treated with water in the present invention may have an oval or polygonal cross section, but it is preferably a circle. The outer diameter of the nozzle of the pipette to be treated may be constant or may vary in the length direction, but it is preferable that the pipette is a rotating body having a flat surface at least near the tip. In the present invention, a liquid retaining surface is provided on the outer peripheral portion within the range of 0.3 to 10 mm from the tip portion. The reason is described in the section of the effect of the invention.

In order to provide the liquid retaining surface on the two members, cloths, felts, papers, non-woven fabrics, strings, or threads may be wound around or attached to the outer surfaces of the members. The liquid holding member should be soft. This is because when it comes into contact with the above range of the pipette, it slightly dents, so that it comes into contact with a relatively large area on the outer periphery of the pipette. The entire member or a portion other than the vicinity of the center may be made of the liquid retaining material.

When practicing the method of the present invention, from the tip of the pipette to 0.
A preferred method is to contact the liquid-retaining surfaces of the two members at the same time within a range of 3 to 10 mm and rotate the pipette between the two surfaces. The liquid retaining surfaces of the two members may both be flat surfaces, or both may be cylindrical surfaces or part of cylindrical surfaces. The liquid retaining surface of one of the two members may be a flat surface, and the liquid retaining surface of the other member may be a cylindrical surface or a part of the cylindrical surface.

It is convenient for the two members to have a liquid-retaining flat surface that can move parallel to each other in opposite directions to rotate the pipette near the tip between the surfaces. For example, if the two members are plate-shaped members each having a flat surface having a liquid-retaining property on the opposite surfaces, the two members are moved in parallel in the opposite directions so that the vicinity of the tip of the pipette is sandwiched between the two flat surfaces. It can be rotated with, which is convenient.

When the two members are cylindrical or cylindrical, it is convenient to rotate them by rotating them in the same direction so as to sandwich the pipette's tip portion between their outer peripheral surfaces.

As a water-repellent liquid used to form a water-repellent surface within the range of 0.3 to 10 mm from the tip of the pipette, silicone oil widely used as a water-repellent treatment agent is available because of its availability and price. It is suitable in that respect. However, among the vegetable oils, animal oils, mineral oils, synthetic esters, higher alcohols, etc., those which can adhere to the outer peripheral surface within the range of 0.3 to 10 mm from the tip of the pipette may be selected and used. It may include a solvent having an appropriate volatility. The silicone oil has a molecular weight of 5000.
It is preferable to use the above.

INDUSTRIAL APPLICABILITY The present invention is useful for water repellent treatment in the vicinity of the tip of a liquid injection nozzle of a pipette used for measuring sample liquids, reagents and the like in clinical chemistry tests. Many pipettes used for spotting chemical analysis slides in clinical chemistry tests have a cylinder and a piston. The pipette may have a fixed nozzle, or may have a detachable or disposable nozzle tip. Nozzle tips are, for example, U.S. Patents 4,072,330, 4.237.095,
Those described in 4,347,875 can be used. Most commercially available nozzle tips are made of polypropylene from the viewpoint of processing accuracy. The outer diameter of the tip of the pipette nozzle is usually
It is about 0.3 mm to 1.5 mm. It is preferably 0.5 mm to 1.2 mm.

When applied to a pipette or the like having a detachable nozzle, the length of the nozzle is not particularly limited, but when the present invention is carried out, the nozzle has such a length that it can be held so as to come into contact with the liquid retaining surface. Need to have In the case of a disposable nozzle tip or the like, the length of the nozzle is naturally determined by the desired amount of liquid to be contained. In the case of a nozzle having an outer diameter of about 0.5 to 3 mm, the range in which the outer surface near the tip is made water repellent according to the present invention is appropriate to a position apart from about 3 to 10 mm from the tip except for a portion of 0.3 to 1.2 mm from the tip. Is. If the water is made more distant from the tip, the effect of preventing the liquid from flowing down along the outer surface is rather lowered.

EFFECTS OF THE INVENTION According to the present invention, when a certain amount of liquid is discharged once or repeatedly from the tip of the nozzle (discharging pipe) of the pipette used in the analysis, the liquid is discharged to the outside near the tip of the nozzle. Since part of the liquid does not adhere, there is no positive or negative error in the amount of liquid dropped from the nozzle. As a result, it is possible to improve the accuracy of quantitative chemical analysis of components in liquid, for example.

Further, according to the present invention, when the nozzle portion of the pipette is immersed in the liquid relatively deeply for sucking the liquid, the liquid adhered to the outer surface relatively above the nozzle portion gradually flows down and is discharged. It is also possible to prevent the addition of the added liquid (which causes a positive error in the amount of the dropped liquid).

If the tip of the pipette is made water-repellent, the droplets formed on the tip become unstable (fall by a small vibration), so the outer surface of the pipette within a range of 0.3 to 10 mm from the tip is water-repellent treated.

INDUSTRIAL APPLICABILITY The present invention is useful not only for pipettes but also for burettes and the like used for quantitative analysis.

Example 1 A device as shown in FIG. 1 was manufactured. Figure 1 Y is 1X
FIG. 1 is a sectional view taken along the line yy 'of FIG.
Fig. 3 is a view from the bottom with the parts removed. In FIG. 1, 1 is a support frame, 2 and 2'are gutter-shaped members rotatable around fixed shafts 4 and 4 ', and 3 and 3'are fixed to the lower ends of gutter-shaped members 2 and 2', respectively. Liquid holding member, 4 and 4'is a rotary shaft of a gutter-shaped member, and 5 and 5'is a gutter-shaped member.
A spring for urging 2, 2'in opposite directions, 6 is a pipette to be processed, 7 is a pipette holding member, and 8 is a bottom plate. The rectangular parallelepiped liquid holding member 3 is fixed to the lower part of the gutter-shaped member 2, and the liquid holding member 3'is fixed to the lower part of the gutter-shaped member 2 '. One side surface of the liquid holding members 3 and 3 ′ can contact the pipette 6 held by the pipette holding member 7. The pipette holding member 7 has a hole at the center for holding the pipette 6 rotatably. Liquid holding member 3
And 3'are open cell plastic sponges.

An appropriate amount of commercially available silicone oil is soaked in the entire surfaces of the liquid holding members 3 and 3 ', and the pipette 6 to be processed, for example, the nozzle tip of a micropipette is inserted downward into the hole of the pipette holding member 7. At this time, the pipette 6 holds the liquid holding member 3
And 3 '(Fig. 1, X, Z, Fig. 2, A, C). When the back of the gutter-shaped members 2 and 2'is pushed inward with a finger, the gutter-shaped member 2 resists the bias of the spring 5 and moves to the right in the figure,
The gutter-shaped member 2'is moved leftward in the figure against the bias of the spring 5 '. This causes the liquid holding members 3 and 3'to contact the pipette 6 and rotate between the liquid holding members 3 and 3'clockwise (as viewed from above) with respect to the pipette 6 (see FIG. 2B, B).
See D).

The tip of the pipette 6 is located below the liquid holding members 3 and 3'and does not contact them.

Since the portion near the tip of the pipette 6 rotates in contact with the liquid holding members 3 and 3 ', the surface in contact with the liquid holding members 3 and 3'extends the entire circumference of the pipette 6 during the rotation. That is, silicone oil adheres to the entire circumference within a range of 0.3 to 10 mm from the tip of the pipette 6 to form a water-repellent surface.
Silicone oil does not adhere to the tip of the pipette. In this way, a water-repellent surface was formed on the outer surface within a range of 0.3 to 10 mm from the tip of the pipette 6.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in three directions showing a ready-to-use state of the apparatus used in Example 1 of the present invention, FIG. 2 is a schematic view showing the operation of the main part of the apparatus, and FIG. 3 is a method of the present invention. FIG. 4 is a schematic view showing a state of droplets formed on the treated nozzle tip, and FIG. 4 is a schematic view showing a state of droplets formed on a nozzle tip (prior art) which does not have a water-repellent surface on its outer periphery. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B05D 1/40 B05D 1/40 G01N 1/00 101 G01N 1/00 101K 35/10 35/06 D

Claims (6)

(57) [Claims] 1. Two members (3, 3) having a liquid retaining surface.
3 ') is made to hold a liquid having a property of imparting water repellency to the liquid-holding surface, and the vicinity of the tip of the pipette (6) is held on the liquid-holding surface of the two members (3, 3'). A method of contacting to form a water-repellent surface on the outer surface within a range of 0.3 to 10 mm from the tip of the pipette (6). 2. The method according to claim 1), wherein the liquid retaining surface is flexible. 3. A pipette (6) is brought into contact with the liquid-retaining surfaces of the two members (3, 3 ') at the same time within a range of 0.3 to 10 mm, and the pipette ( The method of claim 1), wherein 6) is rotated. 4. The method according to claim 1, wherein the liquid retaining surfaces of the two members (3, 3 ') are both flat. 5. A pipette (6) and two members (3, 3 ') for holding a liquid having a liquid-retaining surface and having a property of imparting water repellent property to the liquid-retaining surface. Means for holding the pipette (6) so as to rotate between the two surfaces (3, 3 ') while simultaneously contacting the liquid-retaining surfaces of the two members (3, 3') within a range of 0.3 to 10 mm from the portion ( 7) and means (2 and 3) for moving the two members (3, 3 ') such that the liquid-retaining surfaces of the two members (3, 3') move in opposite directions along the surfaces. 5, 2'and 5 '), an apparatus for forming a water repellent surface on the outer surface within the range of 0.3 to 10 mm from the tip of the pipette. 6. Device according to claim 5), characterized in that said two members (3, 3 ') have liquid-retaining planes which can move parallel to one another in opposite directions.