JPH02227629A - Method for improving reproducibility of suction amount of sample by peristalic pump - Google Patents

Abstract

PURPOSE:To improve the reproducibility of the suction amount of a sample by detecting the positions of rotors of the peristalic pump at a predetermined position and rotating the rollers by a specific angle based upon the predetermined position as an origin. CONSTITUTION:For a sample liquid feeding method when, for example, the disk 11 of the peristalic pump 1 is rotated by a quarter, the rotation angle detecting device consisting of a disk 8 and a photocoupler 9 is fitted on the rotary shaft 4 of a stepping motor 3 which drives the pump 1 and the photocoupler 9 is connected to a CPU 10. Then a roller A is set at the lowest point before the sample is sucked. Then the disk 8 is rotated by a quarter turn with a sample suction start signal and the sample is sucked during this period. When the disk 8 is further rotated by a quarter turn, a roller E which is closest to the lowest point is put at the lowest point. Then the roller E is rotated by a quarter turn and the sample is sucked during this period. Each roller of the pump 1 starts at a predetermined position at all times by said operation and rotates by the prescribed angle. The suction amount of the sample, therefore, becomes constant.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a method for introducing a sample into a sample analyzer, comprising:
In particular, it relates to a method of introducing a sample into a spectrophotometer using a peristaltic pump. [Prior art] When a sample is analyzed using a spectrophotometer, a peristaltic pump, which is a type of sample ladder pump, is used to send a fixed amount of sample from the sample cup to the spectrophotometer. Six rollers are installed at equal angular intervals, and the rollers squeeze a tube with one end inserted into the sample liquid in the sample cup, and the resulting pressure difference is used to send the sample to the spectrophotometer. ing. Conventionally, such a peristaltic pump rotates a disk regardless of the stop position (stop angle) of the roller at the start of rotation. [Problems to be Solved by the Invention] Due to the structure of the peristaltic pump described above, there is pulsation caused by the roller when rotating the disc, so when pumping a large amount of sample such that the suction amount is more than one revolution, the influence of pulsation However, when the amount of liquid fed is small and the number of rotations is low, such as a quarter turn, the amount of suction (amount of liquid fed) changes depending on the position (angle) of the roller at the start. do. There is a problem in that such a change in the amount of sample inhaled (amount of liquid sent) results in fluctuations in the analysis results, resulting in measurement errors. This invention was made in order to solve this problem, and its purpose is to provide a sample using a peristaltic pump in which the number of revolutions of the disc is small and the amount of sample taken in is constant regardless of the position of the roller. The objective is to provide a method for improving the amount of inhalation and reproducibility. [Means for Solving the Problems] That is, in order to solve the above-mentioned problems, the present invention provides a method for improving the reproducibility of the amount of sample taken in by a peristaltic pump, which provides a rotation angle detection device attached to the drive shaft of a motor that drives the peristaltic pump. and a central processing unit, detect the position of the roller of the peristaltic pump that is at a predetermined position and closest to the position rearward in the rotational direction, and drive the motor to rotate the roller so that it comes to the predetermined position. let me,
Furthermore, the roller is rotated by a predetermined angle using the position as an origin. [Operation] Each roller of a peristaltic pump always starts from a predetermined position and rotates by a predetermined angle. Therefore, the amount of sample inhaled is always constant. Further, if the start position and rotation angle are determined, it can be similarly applied even if the start position and rotation angle are changed.

【Example】

Hereinafter, a method for improving the reproducibility of sample suction amount using a peristaltic pump according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an apparatus configuration for carrying out the method according to the present invention. In this figure, l is a Verista pump, around which an elastic tube 2 is wound. A stepping motor 3 drives the peristaltic pump 1 with a drive shaft 4. The tube 2 is connected to a flow cell 5 of a spectrophotometer, and the sample P in the sample cup 7 is sucked into the flow cell 5 through a tube 6. In this case, the tube 2 and the tube 6 are connected in the flow cell 5, and the sample P is sucked by the differential pressure generated by the rotation of the peristaltic pump 1. Further, a disk 8 having a large number of holes 8a, 8b, 8C-. is fixed to the drive shaft 4 of the stepping motor 3 at the opposite end thereof. Reference numeral 9 denotes a photocoupler, which detects the position of a roller (described later) of the peristaltic pump 1 by detecting a large number of holes 8a, 8b, etc. in the disk 8. That is, the disc 8 and the photocoupler 9
constitutes a roller rotation angle detection device. Reference numeral 10 denotes a central processing unit (hereinafter referred to as CPU), which is connected to the stepping motor 3 and the photocoupler 9. FIG. 2 is an enlarged detailed view of the peristaltic pump I. In the embodiment shown in FIG. 0, six rollers are attached to the disc 11 at equal angular intervals, as indicated by symbols A to F. When the disk i1 rotates, each roller presses the tube 2 against the guide 12 while suctioning the sample P and feeding the sample P. Next, with reference to FIG. 3, a description will be given of a sample liquid feeding method when, for example, the disk 11 is rotated by one-fourth of a turn using this apparatus having the above configuration. First, as shown in Fig. 1 or 2, the rotary shaft 4 of the stepping motor 3 that drives the peristaltic pump l is made up of a disc 8 and a photocoupler 9, each having holes 8a, 8b, and 8 cm in diameter. A rotation angle detecting device is attached thereto, and the photocoupler 9 is connected to the CPU10. In this way, the necessary rotation angle of the rollers can be freely set and detected by the CPU 10 based on the correlation between the number of rollers 8a, 8b, etc. and the number of rollers. ■ Before suctioning the sample, bring roller A to the lowest point [Figure 3 (1)]. ■The disk 8 is rotated by a quarter rotation in response to the sample suction start signal, and the sample is aspirated during this time [Figure 3 (2)
)). 0 Next, when the disk 8 is rotated a quarter of a turn, as shown in Fig. 3 (2
), the roller E closest to the lowest point is brought to the lowest point by the program input to the CPU 10 (FIG. 3 (3)). ■Similarly, rotate roller E a quarter turn from the position shown in Figure 3 (3), and suck the sample during this time [Figure 3 (4)]
, and so on, repeating the operations of ■ and ■. Through the above operations, each roller of the peristaltic pump always starts from a predetermined position and rotates by a predetermined angle. Therefore, the amount of sample inhaled is always constant. In the embodiment of this invention, the starting position of the rollers A to F is the lowest point, and the disc 8 is rotated by a quarter of a turn. This can be applied even if the position or rotation angle is changed. When changing the 0 rotation angle, the disk 8 of the rotation angle detection device attached to the drive shaft 4 should be moved to a different circle so that the hole position matches the intended rotation angle. You can apply it by changing it to a board. Although a disk 8 with holes 8a, 8b, and a photocoupler 9 were used as the rotation angle detection device, other devices capable of detecting the rotation angle may be used, such as a device using an electromagnet or a device using a diode. In that case, other devices may be used. [Effects of the Invention] Since the method for improving the reproducibility of the amount of sample inhaled by the peristaltic pump according to the present invention is configured as detailed above, it is possible to suppress fluctuations in the amount of inhalation due to pulsation of the tube 2 and obtain stable measurement results. It becomes like this. FIG. 4 shows the relationship between the rotation start position of the roller and the suction amount measured by the method according to the present invention. In other words, referring to the position of the roller shown in FIG. The suction amount when each roller rotates is shown as I-1, I-2, and I-3, and the suction amount when each roller rotates from the position of ■ is ll-1, ll-2, and ll-3. (The arithmetic numerals at the end represent the number of measurements). In this way, there is a difference in the amount of inhalation when starting from position ■ and when starting from position I. Therefore, as is clear from the data shown in this figure, if the roller is always started from a fixed position, the penetration amount will be constant and the measured value will be stable.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an apparatus configuration for implementing the method according to the present invention, FIG. 2 is an enlarged detailed view of the peristaltic pump,
Fig. 3 is a diagram showing the position of each roller when the disk of the peristaltic pump used in the invention according to this method is rotated by a quarter turn, and Fig. 4 is a diagram showing the rotation of the rollers measured by the method according to this invention. It is a figure showing the relationship between a starting position and an inhalation amount. 1 - Peristaltic pump 2 - Tube 3 - Stepping motor 4 - Drive shaft 5... Flow cell
8-...Disk 9--Photocoupler 1 (1-CPU Applicant Shimadzu Corporation Representative Patent Attorney Maki Kawasaki Figure 1

Claims (1)

[Claims] (1) Using a rotation angle detection device attached to the drive shaft of the motor that drives the peristaltic pump and a central processing unit, detect the position of the roller of the peristaltic pump that is closest to the predetermined position and rearward in the rotational direction. A method for improving the reproducibility of a sample suction amount using a peristaltic pump, characterized in that the motor is driven to rotate the roller so that the roller comes to the predetermined position, and the roller is further rotated by a predetermined angle using the position as an origin.