JPH04274765A - Method for controlling dispensing in sample dispensing device - Google Patents

Abstract

PURPOSE:To effectively prevent the sample which has been weighed and sucked in a titration tip mounted on a sampling head of a sample dispensing device from dripping while a titration tip is moved to a separation position when sample sampled from products is separately titrated to be analyzed for the purpose of quality control of volatile product such as solvent separated and purified from crude oil in a petroleum plant or the like. CONSTITUTION:A syringe 3 of a sample dispensing device is actuated as predetermined whereby a plurality of cycles of suction and discharge are repeated by the syringe 3 while the lower end of a titration tip 21 reaches a liquid surface of the sample in the sample bottle 1 before the titration tip 21 mounted on a sampling head 2 weighs and sucks a predetermined amount of sample in the sample bottle 1, so that vapor pressure of sample in a path 6 from the titration tip 21 to the syringe 3 is made close to saturated vapor pressure. Then the syringe 3 is allowed to perform suction for weighing a predetermined amount to have the titration tip 21 to weigh and suck the sample.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a method for controlling the quality of various solvents and volatile chemical raw material liquids that are separated and refined from crude oil in petroleum plants, etc. The present invention relates to a dispensing control method in a sample dispensing device used when analyzing and inspecting the moisture content of a sample.

0002

[Prior art] Various solvents and volatile industrial raw material liquid products that are separated and refined from crude oil at oil plants, etc. are manufactured in order to keep the stability, composition, and purity of the products within specifications. In the final step of the process, quality control is performed by sampling and analyzing samples at fixed purification amounts and time intervals.

[0003] Quality control based on this analytical test is particularly important because moisture contamination in various solvents deteriorates the quality of the product.

[0004] However, conventional moisture analysis tests use a highly reliable trace moisture measuring device that has already been developed, and manually extracts a predetermined amount (usually 5cc, 0.5cc, 0.05c
c) Titration is carried out to detect and measure the water content.

[0005]

[Problems to be Solved by the Invention] In conventional analytical testing, the moisture meter itself has high accuracy, but in addition, the work of dispensing and titrating minute amounts for analytical testing is done manually using a pipette. Because of this process, there are many errors in the titration amount, and there are problems with efficiency.

[0006] The present invention has been made in order to solve these problems occurring with conventional means, and enables the collection and titration of small amounts of samples to be performed accurately and efficiently. The purpose is to propose new means.

[0007]

[Means for Solving the Problems] The present invention has been completed based on knowledge obtained through various studies and experiments in order to achieve the above-mentioned objects.

That is, for the above-mentioned purpose, the applicant first developed a sample dispensing device A that can accurately and efficiently perform weighing and titration dispensing of minute amounts of a sample.

As shown in the front view of FIG. 1 and the developed view of FIG. 2, this sample dispensing device has a box-shaped body a.
A turntable b supports sample bottles 1 filled with collected samples in a circular arrangement, and caps 10 of the sample bottles 1 move sequentially by the intermittent rotation of the turntable b.
An automatic lid opening/closing device unit u that automatically opens the lid, and a sampling system that uses the unit u to aspirate a sample liquid from inside the sample bottle 1 from which the cap 10 has been removed to a titration tip 21 attached to a nozzle 20 and weigh a predetermined amount. A head 2, a syringe 3 that performs suction and discharge operations on a titration tip 21 attached to a nozzle 20 of the head 2, a vertical movement device c that moves the sampling head 2 up and down, and a vertical movement device c that moves the sampling head 2 left and right. a left-right moving unit d, a specific gravity measuring device e for measuring the specific gravity of a sample weighed by the titration tip 21 of the sampling head 2, and a titration tip 21 at the tip of the nozzle 20 of the sampling head 2, which measures the specific gravity of the sample weighed by the titration tip 21; There is a trace moisture measuring device f that detects the moisture value of the sample by titrating the sample, and a controller g that controls the operation of each of these devices (
3), a tip rack h that stores the titration tips 21 attached to the sampling head 2, a data processing computer i, a printer j, and a display k that record the data detected by each device. be.

[0010] As a result, a predetermined amount of sample is first weighed from the sample bottle 1 on the turntable b onto the titration tip 21 of the sampling head 2 by the operation of the syringe 3 (usually 5mi, 500μl, 50μl). amount) is discharged and titrated into the flask of the specific gravity measuring device e, the specific gravity is measured, and the data is sent to the data processing computer i.

Next, the sampling head 2 is returned to the position of the sample bottle 1 where the sample was weighed, and the operation of weighing the same amount is performed again, and the very small amount of sample that has been weighed is Detect moisture by discharging into a trace moisture measuring device f, correcting the data with the specific gravity measured and detected by the aforementioned specific gravity measuring device e, and determining the moisture value of the sample,
I am trying to record it.

[0012] Furthermore, the sampling head 2 for collecting the above-mentioned sample has, as shown in FIGS. 3 and 4,
A panel 4 that forms the body of a left-right moving unit d that is supported on the fuselage a so as to be movable in the left-right direction (in the direction of arrow W in FIG. 3) and is moved left and right by a left-right moving motor (not shown). It is supported so that it can freely move up and down along a guide groove 40 formed in the panel 4. The panel 4 is rotated by a motor M1 assembled to the panel 4 and driven by the motor M1.
A driving wheel 50 is pivotally supported on the panel 4, and a driven wheel 51 is freely pivotally supported on the panel 4 opposite to the driven wheel 51.
The motor M1 is controlled by a controller g equipped with a computer installed in the machine body a, and is driven to rotate in forward and reverse directions, thereby moving up and down by a desired amount.

[0013] Also, the nozzle 2 of the sampling head 2
The syringe 3 for suctioning and discharging the
A cylinder 30 is fixedly supported on the panel 4 constituting the body of the left-right moving unit d that moves the sampling head 2 left and right, with the axial direction being the vertical direction, and a piston 31 is slidably fitted into the panel 4. the lower end of
A holder 33 that fits into a guide rod 32 fixedly supported on the panel 4 and moves up and down is supported, and the holder 33 is attached to a threaded rod 34 that is pivotally supported on the panel 4 in parallel to the guide rod 32. Female thread 35 to be screwed together
A conduction pulley 36 is connected to the output shaft of the motor M2 and its threaded rod 34 is supported on the panel 4.
is transmitted through the transmission belt 37 and the transmission pulley 38, and this motor M2 is controlled by the aforementioned controller g to rotate forward or backward by a desired amount, so that the piston 31 moves up and down the desired amount to perform suction operation. and discharge operation.

[0014]The upper end side of the cylinder 30 of this syringe 3 is connected through a passage 6 consisting of tubes 60 and 61.
A titration tip is connected to and communicates with the upper end of the nozzle 20 provided in the sampling head 2 described above, and is removably inserted into the tip side of the nozzle 20 by suction and discharge operations caused by the vertical movement of the piston 31 described above. At 21, the sample is sucked and discharged.

Further, in FIGS. 3 and 4, a member indicated by reference numeral 7 provided in the middle of the tubes 60 and 61 connecting between the syringe 3 and the nozzle 20 of the sampling head 2 is a member indicated by the reference numeral 7, which is connected to the passageway by the operation of the syringe 3. This is a pressure sensor that detects the pressure generated within the titration tip 21 via the titration tip 6.

The pressure sensor 7 is connected to the sampling head 2
3, insert the titration tip 21 into the sample bottle 1, insert the lower end of it into the sample liquid, and aspirate a predetermined amount of sample by operating the syringe 3. After that, the sampling head 2 is raised again and moved left and right, and transported to the trace moisture measuring device f, where
This is to prevent weighing errors from occurring due to the addition of the sample attached to the outer surface of the titration tip 21 when discharging the sample weighed into the titration tip 21 for titration. .

That is, when the tip of the titration tip 21 comes into contact with the liquid surface of the sample in the sample bottle 1 due to the descent of the sampling head 2, the pressure inside the passage 6 changes. The sensor 7 detects that the tip of the titration tip 21 has come into contact with the liquid surface of the sample, and at that point the controller g is instructed to stop the descent of the sampling head 2, and the outer surface of the titration tip 21 is This is used to prevent excess sample from adhering to the surface.

The sample dispensing device A configured as described above is such that when the syringe 3 and the sampling head 2 perform predetermined operations, the titration tip 21 provided on the sampling head 2 measures out a predetermined amount of sample. It should be possible to titrate to the trace moisture measuring device f, but in reality, a part of the sample weighed on the titration tip 21 is
Errors occur as the material begins to fall off during the movement of the material. This dropping of the sample from the titration tip 21 inevitably occurs even if the sampling head 2 is moved at a slow speed.

Therefore, this weighed sample titration tip 2
Upon further investigation into the phenomenon of droplets from 1, it was found that the sample weighed into the titration tip 21 is a volatile liquid such as a solvent separated and purified from petroleum, so it vaporizes inside the titration tip 21. It has been found that this is due to the pressure in the passage 6 from the syringe 3 to the sampling head 2 increasing due to the vapor pressure of the sample generated by this.

[0020] Therefore, further study was carried out, and titration tip 2
When we waited until the vapor pressure of the vaporized gas that was vaporized from the volatile sample sucked into the chamber 1 and filled the passage 6 reached the saturated vapor pressure at that temperature, the droplets stopped and became stable. It started coming.

From this, it can be seen that the vapor pressure of the volatile sample sucked into the titration chip 21 in the passage from the titration chip 21 to the syringe 3 is equal to that of saturated vapor. It has been found that if the pressure is at or close to this pressure, the material can be moved in a stable state without causing any dripping.

However, it takes time to wait until the vapor pressure of the sample in the passage 6 naturally reaches the saturated vapor pressure.

Therefore, after the volatile sample is sucked into the titration tip 21 by the suction operation of the syringe 3, the operation of discharging it is repeated, and the sample adheres to the inner wall surface of the titration tip 21. By repeatedly creating a state in which the substantial evaporation surface of the sample in the passage 6 was significantly expanded, the time required for the vapor pressure of the sample in the passage 6 to reach the saturated vapor pressure and become stable was significantly shortened. I know what's coming.

From this, the titration tip 21 attached to the sampling head 2 by the operation of the syringe 3
Before performing the suction operation to weigh a predetermined amount of feed, the syringe 3 is repeatedly subjected to suction and discharge operations with the lower end of the titration tip 21 reaching the liquid level of the sample in the sample bottle 1. Then, the vapor pressure of the sample in the passageway 6 is brought close to the saturated vapor pressure, and then the syringe 3
When the controller g controls the operation of the syringe 3 so that the titration tip 21 performs a suction operation to measure a predetermined amount of sample, the sample dispensing device A is driven to perform a sample analysis test. The result is that the dispensing operation can be performed with almost no effect on the overall time of the operation process, and while effectively preventing the sample from dropping onto the titration tip 21. Ta.

Based on this result, in the present invention, as a means for achieving the above-mentioned object, the sampling head 2 supported on the aircraft body a is moved up and down and moved left and right. In a sample dispensing device, a syringe 3 connected to a titration tip 21 attached to a sampling head 2 through a passage 6 performs weighing suction and dispensing titration operations. Before the titration tip 21 attached to the sample bottle 2 aspirates a predetermined amount and weighed amount of the sample in the sample bottle 1, the lower end of the titration tip 21 is attached to the sample bottle 1.
When the liquid level of the sample in the titration tip 2 is reached, the syringe 3 repeats suction and discharge operations several times, and the titration tip 2
The vapor pressure of the sample in the passage 6 leading from the syringe 1 to the syringe 3 is brought close to the saturated vapor pressure, and then the syringe 3
The present invention proposes a dispensing control method in a sample dispensing device, which is characterized in that the titration tip 21 is controlled to perform a suction operation to weigh out a predetermined amount of sample, thereby causing the titration tip 21 to suck a measured amount of sample.

[0026]

[Example] Next, an example will be described in detail. The implementation of the method of the present invention is
This is carried out using the sample dispensing apparatus A shown in FIGS. 1 to 4 described above. However, the controller g with a built-in computer that controls the operation of the syringe 3 and the sampling head 2, as shown in FIG. When the liquid level of the sample in the sample bottle 1 has been reached, and before a predetermined amount of the sample is weighed and suctioned into the titration tip 21 by the operation of the syringe 3, in that state, the syringe 3 is in suction operation. Repeat the dispensing operation multiple times, and after that operation, insert the titration tip 2 into the titration tip 2.
In step 1, settings are controlled so that a predetermined suction operation for weighing and suctioning a predetermined amount of sample is performed.

In this way, using the above-described sample dispensing device A in which the operations of the syringe 3 and the sampling head 2 are controlled by the controller g, volatile solvents such as various solvents that are separated and purified from crude oil can be extracted at an oil plant or the like. Samples collected from the purified products in the final process of their production are packed into sample bottles 1..., and the sample bottles 1... are placed in parallel on the turntable b of the sample dispensing device A. , by driving the sample dispensing device A, the turntable b
The sample bottles 1 are sequentially sent below the suction operation position of the sampling head 2, and the sampling head 2 and silicin 3 are made to perform predetermined operations, so that the weighed sample is sucked from the sample bottle 1 into the titration chip 21. Dispense and titrate using the trace moisture measuring device f. At this time, in order to avoid sample contamination, the titration tip 21 attached to the sampling head 2 is attached to the sampling head 2 for each suction/dispensing process that combines weighing and aspiration of the sample and dispensing titration. Device A
The titration tip 21 is replaced with a new titration tip 21 taken out from the titration tip rack h installed in the machine a.

As a result, the sample dispensing operation by the control operation of the sampling head 2 and syringe 3 of the sample dispensing device A is performed until the lower end of the titration tip 21 attached to the sampling head 2 reaches the liquid level in the sample bottle 1. By the way, due to the sample suction and discharge operations repeated multiple times, the vapor pressure of the sample in the passage 6 between the titration tip 21 and the syringe 3 approaches the saturated vapor pressure, and the pressure in the passage 6 decreases. In this state, a predetermined amount of sample is weighed and suctioned into the titration chip 21, and this sample is transported to the trace moisture measuring device f and titrated and dispensed, so the titration chip 21 is moved. The dispensing operation can be performed while effectively suppressing the dripping that occurs during dispensing.

[0029] Furthermore, this means further includes the step of moving the titration tip 21 after finishing the weighing suction operation by the titration tip 21. Titration tip 2 by pressure
A sensor 7 detects the increase in the pressure in the passage 6 between the sample 1 and the syringe 3 using the pressure provided in the passage 6, and the detection signal causes the syringe 3 to move towards the increasing pressure of the sample. The titration tip 2 has been controlled so that the suction operation is performed by the amount corresponding to the vapor pressure, and the suction operation for weighing has been completed.
1 may be used in combination with means for keeping the pressure in the passage 6 constant during the process of moving the passage 6.

[0030] In this case, control to stabilize the pressure fluctuations in the passage 6 is achieved by repeating the suction and discharge operations of the syringe 3, which are performed before the weighing suction process by the titration tip 21. This condition is corrected by the suction operation of the syringe 3, which operates to maintain a constant pressure in the passage 6 while the titration tip 21 is moved after the suction operation for weighing has finished. The repeated operation of suction and discharge is performed to evaporate the vapor pressure to bring it close to the saturated state and stabilize it, and the suction operation of the syringe 3 is performed to maintain the pressure inside the passage 6 constant. , in a very short time and accurately.

[0031]

As explained above, in the means of the present invention, when performing a sample dispensing operation using the sample dispensing device A, the operation of the syringe 3 causes the sampling head 2 to
Before weighing and suctioning a predetermined amount of sample into the titration tip 21 attached to the syringe 3, with the lower end of the titration tip 21 reaching the liquid level of the sample in the sample bottle 1, the syringe 3 is injected with suction and discharge. By repeating this operation multiple times to actively vaporize the sample, the vapor pressure of the sample in the passage 6 from the titration tip 21 to the syringe 3 is brought to the saturated vapor pressure or a pressure close to it. The pressure is kept stable, and then the syringe 3 is made to perform a suction operation to weigh a predetermined amount of sample, and the titration chip 21 is made to suction the sample. Dropping of the sample during the process of moving the tip 21 is effectively suppressed, and the dispensing titration of a precisely weighed volatile sample can be carried out precisely and efficiently.

[Brief explanation of the drawing]

FIG. 1 is a front view of the entire sample analysis device used to implement the method of the present invention.

FIG. 2 is a developed view of the same device.

FIG. 3 is a perspective view of essential parts of the above device.

FIG. 4 is a longitudinally developed view of the main parts of the device.

[Explanation of symbols]

A...sample dispensing device, a...body, b...turntable, c
... Vertical movement device, d... Lateral movement unit, e... Specific gravity measuring device, f... Trace moisture measuring device, g... Controller, h
...chip rack, i...data processing computer, j
...Printer, k...Display, u...Automatic lid opening/closing device unit, M1...Motor, M2...Motor, 1...Sample bottle, 10...Cap, 2...Sampling head, 20...
Nozzle, 21...Titration tip, 3...Syringe, 30...Cylinder, 31...Piston, 32...Guide rod, 33...Holder, 34...Threaded rod, 35...Female thread, 36...Conduction pulley, 37...Conduction belt, 38...Conduction Pulley, 4... Panel, 50... Driving wheel, 51... Driven wheel, 52... Belt, 6
...Passway, 60...Tube, 61...Tube, 7...Pressure sensor.

Claims (1)

[Claims] Claim 1: While the sampling head 2 supported on the body a is moved up and down and left and right, the titration chip 21 attached to the sampling head 2 is
In a sample dispensing device that performs weighing suction and dispensing titration by the operation of a syringe 3 connected to the sampling head 2 through a passage 6, the operation of the syringe 3 causes a titration tip 21 attached to the sampling head 2 to be , before aspirating a predetermined amount and weighed amount of the sample in the sample bottle 1, the syringe 3 performs multiple suction and discharge operations while the lower end of the titration tip 21 reaches the liquid level of the sample in the sample bottle 1. This is repeated several times to bring the vapor pressure of the sample in the passage 6 from the titration tip 21 to the syringe 3 close to the saturated vapor pressure, and then the syringe 3 is caused to perform a suction operation to weigh out a predetermined amount. A dispensing control method in a sample dispensing device, characterized in that the titration tip 21 is controlled to weigh and aspirate a sample.