JPH0612535Y2 - Auto sampler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an autosampler for automatically supplying a sample in a spectrophotometer, a flame atomic absorption spectrophotometer or the like used in chemical analysis.

[Conventional technology]

In the spectrophotometer, as shown in FIG.
The sampler nozzle 2 attached to the sample cup 3 is inserted into the sample M placed in the sample cup 3, while the tube (fluororesin tube) 4 connected to the nozzle 2 is connected to the flow cell 21.
The sample is sucked into the pump 22 by a predetermined amount and analyzed. Similarly, in a flame atomic absorption spectrophotometer, as shown in FIG. 6, a sampler nozzle 2 attached to a sampler arm 1 is inserted into a sample M placed in a sampler cup 3, and a tube (made of fluororesin) connected to the nozzle 2 is used. The tube 4 is introduced into the atomic absorption burner 23, and the sample is sucked and analyzed. However, in this flame atomic absorption spectrophotometer, the sample is supplied by the differential pressure generated by the combustion of gas in the burner. In any of the above cases, the sampler arm 1 is moved onto the target sample cup 3 in a preset order and then lowered.

[Problems to be solved by the device]

When lowering the sampler nozzle 2, the lowering speed is constant regardless of the sample suction speed, that is, the lowering speed of the sample liquid surface, and the lowering position of the sampler nozzle 2 is constant regardless of the sample suction amount or the suction time. Is. Therefore, as shown in FIG. 4, the tip of the sampler nozzle 2 is lowered to the vicinity of the bottom of the sample cup 3 from the beginning to suck the sample M. As a result, the area around the sampler nozzle 2 is always contaminated with a large sample, which causes carryover and contamination during the next sample measurement, making accurate measurement difficult. The present invention has been made in view of such a problem, and an object thereof is to provide an autosampler that minimizes sample contamination of the sampler nozzle 2 and enables more accurate sample analysis.

[Means for Solving the Problems]

A sampler nozzle and a sampler arm that holds the sampler nozzle fixedly, a sample suction device, a vertical drive device such as the sampler arm, a flow rate control unit of the sample suction device, and a drive control unit of a vertical drive device such as a sampler arm. When,
In the autosampler having a means for calculating the liquid level lowering speed of the sample put in the sample cup based on the signal from the flow rate control unit of the sample suction device, and the vertical movement of the sampler arm etc. based on the liquid level lowering speed. The driving device is provided with a central processing unit including a means for outputting the descending speed of the sampler arm or the like.

[Action]

When the vertical drive device of the sampler arm is operated and the sampler nozzle is lowered, the sampler reaches the sample and begins to suck the sample, and at the same time, the central processing unit (hereinafter referred to as CPU) receives the signal from the flow rate control unit of the sample suction device. Based on this, the liquid level descending speed is calculated. Then, according to an instruction from the CPU, the vertical drive device for the sampler arm lowers the sampler nozzle at a speed slightly lower than the liquid level lowering speed as the sample descends. The tip of the sampler nozzle is slightly inserted into the sample until the analysis is completed. It remains in the open state. Therefore, the sampler nozzle is very rarely contaminated by the sample. If the stop signal is immediately sent to the CPU when the analysis is completed while the sampler nozzle is descending, the sampler nozzle stops descending and returns to the original position.

〔Example〕

Hereinafter, a specific embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an autosampler according to the present invention. A sampler nozzle 2 for sucking the sample M in the sampler cup 3 is fixedly attached to the sampler arm 1. The sampler arm 1 is fixed to, for example, a shaft 6 having a rack 5, and the rack 5 is meshed with a pinion 8 fitted to the shaft of a motor 7. That is, the rack 5, the shaft 6, the motor 7, and the pinion 8 constitute a vertical drive device 10 for the sampler arm 1, that is, the sampler nozzle 2. The vertical drive device 10 may be an air cylinder, a hydraulic device, or the like instead of the rack and the pinion.

Reference numeral 11 is a sample suction device, for example, a pump that guides the sample to the flow cell in the case of a spectrophotometer, and an atomic absorption burner in the case of a flame atomic absorption photometer (in this case, the sample is supplied by the differential pressure generated by the combustion of gas) Is. 1
A central processing unit (hereinafter referred to as a CPU) 2 is used for the motor 7 of the vertical drive unit 10 of the sampler arm 1 and the flow rate control unit of the sample suction unit 11 (pump rotation speed control unit or combustion gas of atomic absorption burner). Valve control unit, etc.).

The autosampler according to this invention is configured as described above. FIG. 2 is a block diagram thereof. The operation will be described with reference to this drawing. Various suction speeds of the sample sucked by the sample suction device 11, that is, data regarding the liquid surface lowering speed of the sample M in the sampler cup 3 calculated from the sample flow rate per unit time are previously stored. It is obtained and input to the CPU 12.

In this case, the spectrophotometer inputs the relationship between the rotation speed of the pump and the liquid level lowering speed, and the flame atomic absorption photometer inputs the relationship between the consumption amount of the combustion gas per unit time and the liquid level lowering speed.

Next, the descending speed of the sampler arm 1 with respect to the rotation speed of the motor 7 of the vertical drive device 10 is calculated in advance, and the descending speed of the sampler arm 1, that is, the descending speed of the sampler nozzle 2 is calculated from the liquid surface descending speed calculated by Input to the CPU 12 so as to be slightly faster.

A drive device 1 for driving the sampler arm 1 when the tip of the sampler nozzle 2 comes near the bottom of the sampler cup 3.
0 to stop and reverse to return to the original position CPU12
Input to. In this case, the descending distance L of the sampler arm 1 may be determined in advance and an instruction to return to the original position when reaching this distance may be given.

When a signal indicating the end of analysis is input, the sampler arm 1 is immediately stopped and input to the CPU 12 so as to return to the original position.

At the same time when the vertical drive unit 10 is turned on, the CPU
From 12 the vertical drive device 10 is commanded to perform the intended operation with respect to the sampler nozzle 2.

FIG. 3 shows a state in which a sample is sucked by the autosampler configured as described above. That is, when the vertical drive device 10 of the sampler arm 1 is operated and the sampler nozzle 2 is lowered in FIG. 1A, the nozzle 2 reaches the sample M and begins to suck the sample M, and at the same time, the CPU 12 controls the flow rate control unit of the sample suction device 11. The liquid surface lowering speed is calculated based on the signal of the central processing unit. Then, according to an instruction from the CPU 12, the vertical drive device 1 for the sampler arm 1 as shown in FIG.
0 causes the sampler nozzle 2 to descend at a speed slightly higher than this liquid level descending speed as the sample M descends. Then, as shown in FIG. 3C, the tip of the sampler nozzle 2 is slightly inserted into the sample M until the analysis is completed.
Therefore, the rate at which the sampler nozzle 2 is contaminated by the sample M is extremely small.

If a stop signal is sent to the CPU 12 immediately after the analysis is completed while the sampler nozzle 2 is descending, the sampler arm 1 stops descending and returns to the original position.

[Effect of device]

Since the autosampler according to the present invention is configured as described above in detail, carryover and contamination can be minimized, and accurate analysis can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an autosampler according to the present invention, and FIG. 2 is a block diagram of an autosampler according to the present invention.
3 (1) to (3) are diagrams showing the positional relationship between the liquid level lowering and the sampler nozzle when a sample is sucked by the autosampler according to the present invention, and FIGS. 4 (1) to (3) are conventional. FIG. 5 is a diagram showing the positional relationship between the liquid level lowering and the sampler nozzle when a sample is sucked by an analyzer such as the spectrophotometer, FIG. 5 is a structural example diagram when the sample is sucked by the spectrophotometer, and FIG.
The figure is a diagram showing an example of the configuration when a sample is sucked in a flame atomic absorption spectrophotometer. DESCRIPTION OF SYMBOLS 1 ... Sampler arm, 2 ... Sampler nozzle 3 ... Sample cup, 5 ... Rack, 6 ... Axis 7 ... Motor, 8 ... Pinion 10 ... Sampler arm up-and-down drive device 11 ... Sample suction device, 12 ... Central processing unit

Claims (1)

[Scope of utility model registration request] 1. A sampler nozzle, a sampler arm that holds the sampler nozzle fixedly, a sample suction device, a vertical drive device such as the sampler arm, a flow rate control unit of the sample suction device, and a vertical drive of the sampler arm and the like. In the autosampler having a drive control unit of the apparatus, means for calculating the liquid level lowering speed of the sample put in the sample cup based on the signal from the flow rate control unit of the sample suction device, and based on the liquid level lowering speed. An automatic sampler comprising a central processing unit including means for outputting the descending speed of the sampler arm or the like to a vertical drive device such as the sampler arm or the like.