JPH01245152A - Sample introducing device for chromatograph - Google Patents

Abstract

PURPOSE:To enable the injection of a slight amt. of a sample with good reproducibility by providing a small hole which communicates with the sample introducing part of a chromatograph to the wall of a sample injector and impressing voltage pulses between an apertured electrode disposed to face the small hole and the sample. CONSTITUTION:The sample introducing part 1 is heated by a heater 2 enclosing said part and a carrier gas flows from a supply pipe 4 through the introducing part 1 into a column 3. The front end of a sample injecting container 5 is projected into the introducing part 1 and the microhole 6 is bored to the tip thereof. An electrode 7 is provided on the inside surface of the container 5 and the apertured electrode 9 is provided in the introducing part 1. The sample soln. is prevented by the pressure of the carrier gas and the surface tension of the sample soln. from going out into the introducing part 1 when the sample soln. is injected into the container 5 at this time, but the sample soln. is attracted by the electric field of a high voltage and is accelerated and ejected from the hole 6 toward the electrode 9 when said high voltage is impressed between the electrodes 7 and 9 by closing a switch 10. The micrliquid drops are, therefore, ejected if the impulsive voltage is impressed to the electrodes. The size of the liquid drops is determined by the diameter of the hole 6 and the voltage and width of the pulses. The liquid drops are thus ejected with the good reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sample introduction device for a chromatograph, and particularly to a device suitable for introducing a small amount of a sample.

(Prior Art) A microsyringe is used to introduce a sample into a gas chromatograph, and the sample is injected into the sample introduction section of the chromatograph. The injected sample is heated and vaporized in the sample introduction section and sent to the column along with the flow of carrier gas. When using a backed column as a chromatography column, the above sample introduction method is sufficient, but when using a capillary column, the amount that can be injected with a microsyringe is too large due to the small loading capacity of the capillary column. Therefore, the sample vaporized at the sample introduction section is split, a fraction of the total is sent to the column, and the rest is discarded.

(Problem to be solved by the invention (2) As mentioned above, when using a capillary column, conventionally, the injected sample is split and only a part is sent to the column, but in this case, problems such as coating occur. The composition of the vaporized sample differs at the beginning and end of vaporization due to the difference in the boiling point of the sample components, and although this is fine if the entire injected sample is vaporized and sent to the column, it is possible to send only a portion of the vaporized sample to the column. In this case, even if the sample is the same, the composition of the sample sent to the column each time varies, resulting in poor reproducibility.

Furthermore, reproducibility is also affected by insufficient heat of vaporization being applied to the sample, insufficient mixing with the carrier, and an inconsistent split ratio of the sample.

Such a problem can be solved by injecting a small amount of the injected sample without having to split it, but such a small amount of injection is difficult with a method using a microsyringe. Therefore, it is an object of the present invention to provide a chromatograph sample introduction device that can inject a minute amount of sample with good reproducibility.

(Means for Solving the Problem) A small hole is provided in the wall of the sample injector so as to be located within the sample introduction section of the chromatograph, and a perforated electrode is disposed close to the small hole to face the small hole. A voltage pulse was applied between the sample inside and the electrode.

Alternatively, a small hole is provided in the wall of the sample injection container so as to be located within the sample introduction section of the chromatograph, and a piezoelectric element is placed inside the container, and a voltage is applied to the piezoelectric element.

(Function) When a sample is injected into the sample injection container, the sample cannot flow out into the sample introduction section of the chromatograph through the small hole in the container wall. This is due to the flow resistance of the small holes, the surface tension of the sample solution, and the fact that the inside of the sample introduction section is under high pressure due to the carrier gas. In this case, if the sample has conductivity, if an electrode is inserted into the sample or an electrode is provided on the wall of the container, the sample will have the same potential as the electrode. When a high voltage is applied between the electrode facing the small hole in the container wall and the electrode in contact with the sample, the sample solution looking through the small hole and the electrode facing the small hole are connected. The sample solution is drawn by the electric field between the electrodes, passes through the small holes, and is accelerated and ejected toward the counter electrode. When the voltage applied between the sample solution and the counter electrode is pulsed, the jet stream is interrupted and minute droplets are ejected from the small holes in the vessel wall. Since the space into which the micro droplets flew out is the sample introduction part of the chromatograph, a sample consisting only of those micro droplets was introduced into the chromatograph. The size of the droplet is determined by the diameter of the small hole, the voltage and width of the applied voltage pulse, and the droplet can be ejected with good reproducibility. The phenomenon of the sample solution flying out in the form of droplets is not the effect of the current flowing within the sample, but the effect of the electric field between the sample and the counter electrode, so the conductivity of the sample does not need to be particularly good. Slight conductivity is sufficient, and when using high voltages,
Applicable to almost all samples.

Instead of using a voltage pulse, a piezoelectric element is placed inside the sample injection container, and when a voltage pulse is applied to the piezoelectric element, the piezoelectric element expands and contracts, a shock wave is transmitted through the sample solution in the container, and the pressure causes a small hole in the container wall to be transmitted. droplets are ejected from the chromatograph into the sample introduction section of the chromatograph. The size of the droplet in this case is the size of the small hole,
Determined by the voltage applied to the piezoelectric element.

(Embodiment) FIG. 1 is an embodiment corresponding to the first claim of this publication. In the figure, 1 is the sample introduction part of the chromatograph, which is surrounded by a heater 2 and heated. 3 is a column following the sample introduction part. Carrier gas is supplied to the sample introduction part 1 from a carrier supply pipe 4, and the carrier gas flows from the supply pipe 4 through the sample introduction part 1 to the column 3. Reference numeral 5 denotes a sample injection container according to the present invention, which is made of heat-resistant glass and penetrates the side surface of the sample introduction section 1 so that its tip protrudes into the sample introduction section.The tip of the sample injection container 5 is pointed. A microhole 6 is bored at the tip of the sample injection container 5.A metal film electrode 7 is provided on the inner surface of the sample injection container 5, and a lead wire 8 is drawn out to the outside of the container 5.In the sample introduction section, the sample injection container An electrode 9 having a hole in the center is provided facing the tip of the switch 10 , and a switch 10 is provided between the electrode 7 and the electrode 9 in the container 5 .
A DC voltage power source 11 is connected through the . The sample injection container 5 is provided with a sample injection tube 51 and a sample discharge tube 52. A valve 53 is provided in the middle of the sample discharge pipe 52. When introducing the sample, the valve 53 is closed, and the sample solution is injected into the sample injection container 5 through the introduction tube 51 using a microsyringe. When the sample solution is filled in the container 5, the microhole 6 at the tip of the container 5 remains open, but due to the pressure of the carrier gas in the sample introduction device and the surface tension of the sample solution, the sample container is pushed into the sample introduction section 1. I won't go out. Switch 1 here
0 is closed, a voltage is applied between the electrode 7 and the counter electrode 9 inside the container 5. Due to the conductivity of the sample solution, the surface of the sample solution peeking through the small hole 6 at the tip of the container 5 also has the same potential as the electrode 7, and is attracted by the electric field between the counter electrode 9 and the small hole 6.
Droplets come out of the hole. When this droplet leaves the tip of the container 5, it retains the charge given by the electrode 8, is accelerated by the counter electrode 9, passes through the central opening of the counter electrode, and hits the opposite wall of the sample introduction part 1. vaporized immediately. The switch 10 is a semiconductor switch that is made conductive for a certain period of time by the output pulse when the switch 13 of another one-shot circuit 12 is closed, and the size of the sample droplet is determined by the diameter of the microhole 6 and the electrode. The amount of sample introduced is determined by the voltage and pulse width applied during 7.9, and the amount of sample introduced is adjusted by turning the switch 13 on and off to adjust the number of droplets. After introducing the sample, close the valve 53.
is opened, the sample solution in the container 5 is drained, and an appropriate cleaning solution is injected into the container 5 to clean the inside of the container 5. 5
Carrier gas is leaking inside. Since this carrier gas has a high temperature, it dries the cleaning liquid in the container 5 in preparation for the next sample introduction. In this embodiment, a septum 14 made of heat-resistant rubber is provided on the upper surface of the sample introduction section 1 so that a sample can be introduced using a microsyringe.

FIG. 2 is an embodiment corresponding to the second claim of this application. Components corresponding to those in the embodiment shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

A piezoelectric element 15 is attached to the rear end of the sample injection container 5. This piezoelectric element is installed so that it extends to the right in the figure by applying a voltage.

The outer diameter of the piezoelectric element is slightly smaller than the inner diameter of the container 5, and its right end surface is like a piston that fits loosely into the container 5. The sample injection tube 51 opens on the side surface of the rear end of the piezoelectric element 15 at the rear end of the container 5 . When introducing a sample, when the container 5 is filled with a sample solution and the switch 10 is closed, a voltage is applied to the piezoelectric element 15 and the piezoelectric element 15 suddenly expands. Therefore, the pressure of the solution in contact with the right end surface of the piezoelectric element 15 increases, and this pressure increase is immediately transmitted to the microhole 6, and one droplet of the sample solution is released from the microhole 6 into the sample introduction part 1. . When the piezoelectric element 15 expands, the pressure of the solution in the container from the right end surface of the piezoelectric element 15 to the microhole 6 increases, but the solution is drawn to the side of the piezoelectric element 15 and moves to the right. As a result of the movement toward the sample injection tube 51, the pressure decreases and the solution does not spill out from the sample injection tube 51. When the switch 10 is closed, droplets are ejected only at the moment the switch is closed, and no droplets are ejected thereafter even if the switch 10 is continuously closed. When the switch 10 is opened, the charge on the piezoelectric element 15 is discharged through the resistor 16, and the piezoelectric element returns to its original length. The size of the droplet is determined by the voltage applied to the piezoelectric element and the diameter of the microhole 6 and is constant. The amount of sample introduced is adjusted by the number of times the switch 10 is turned on and off, that is, the number of droplets. After introducing the sample, a cleaning solution is injected into the container 5 for cleaning. In this embodiment, the piezoelectric element is inside the container 5,
The gaps are narrow and cleaning is difficult. Therefore, piezoelectric element 15
A high frequency power source 17 is connected to the high frequency power source 17, and when this power source is activated, the pressure 7rL element 15 vibrates, and the inner surface of the container 5 and the surface of the piezoelectric element 15 are ultrasonically cleaned. If the high frequency voltage is selected appropriately, the liquid inside the micropore 6 will not be able to follow the high frequency motion.
The washing liquid does not spout out into the sample introduction section 1 from the micropores 6.

(Effects of the Invention) According to the present invention, the sample can be introduced into the chromatograph as droplets of a certain size, and the reproducibility of the droplet size is good, so the amount of sample introduced can be adjusted by the number of droplets. Since a minute amount can be introduced, there is no need to split the sample, and the entire amount of introduced sample can be sent to the column, so it is not affected by the difficulty of evaporation of sample components or the degree of mixing with the carrier gas, making it easy to reproduce. Samples can be introduced with good quality.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of one embodiment of the present invention, and the second leapfrog is a longitudinal sectional side view of another embodiment. ■... Sample introduction part of chromatograph, 2... Heater, 3... Column, 5... Sample injection container, 6... Microhole, 7.9... Electrode, 10... switch, 15・
··Piezoelectric element. Agent: Patent Attorney Kosuke AgataFigure 2

Claims (2)

[Claims] (1) A small hole is provided in the wall of the sample injection container so as to be located within the sample introduction section of the chromatograph, and an electrode is placed in the sample introduction section opposite to this small hole, so that the sample in the sample injection container and the above A chromatograph sample introduction device that applies voltage pulses between the electrodes. (2) A chromatograph in which a small hole is provided in the wall of the sample injection container so as to be located within the sample introduction part of the chromatograph, a piezoelectric element is placed inside the sample injection container, and a voltage is applied to the piezoelectric element. sample introduction device.