JPH04160356A - Sample injection device of capillary electrophoretic apparatus - Google Patents

Abstract

PURPOSE:To inject a sample in a capillary only by electroosmotic flow while suppressing electrophoresis by a method wherein the end of the capillary on the injection side of the sample is covered with a conductive member to be dipped in the sample and the conductive member is used as one electrode. CONSTITUTION:A collar 8 is preliminarily attached to the tip of a capillary 2 on the injection side of a sample and the capillary 2 and the collar 8 are filled with a buffer solution and the collar 8 is connected to the anode of a high voltage power supply 4 to be dipped in the sample 10. The cathode end of the capillary 2 and a cathode 14 are dipped in the buffer solution 12. When migration voltage is applied across both ends of the capillary 2 in this state, the sample is injected in an electrophoretic manner. In this case, since the collar 8 provided at the end of the capillary 2 on the injection side of the sample acts as an electrode, the electric field of the sample solution around the collar 8 becomes uniform. Therefore, no electrophoresis is generated in the sample sucked by electroosmotic flow over the range up to the tip of the capillary. By this method, electrophoresis is suppressed and the sample can be injected in the capillary only by electroosmotic flow.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a sample injection device for injecting a sample into a capillary in a capillary electrophoresis device for separating and analyzing charged substances such as amino acids, proteins, and nucleic acids. .

(Prior Art) As a method for injecting a sample into a capillary, the siphon method and the pressure method are also used, but the electrophoretic sample injection method is widely used because it can be easily performed manually. To inject a sample into a capillary, after filling the capillary with an electrophoresis buffer solution, the capillary end (anode end) 2 on the sample injection side and the anode 16 are immersed in the sample 10, as shown in FIG. The cathode end of the capillary is immersed in a buffer solution, a migration voltage is applied between both ends of the capillary by a high-voltage power supply, and the sample is injected into the anode end of the capillary by electroosmotic flow.

(Problems to be Solved by the Invention) In the conventional electrophoretic sample injection method, as shown in FIG. 3, the tip of the capillary 2 and the anode 16 are separated,
An electric field exists between them. The sample 10 is sucked into the capillary 2 by electroosmotic flow, but at the same time electrophoresis also occurs due to this electric field. In electroosmotic flow, the entire solution flows, but in electrophoresis, the way the ions enter capillary 2 differs depending on their mobility, and the sample injected into capillary 2 has a different composition from the original sample in the sample container, which may cause the analysis results to vary. It has the disadvantage of being inaccurate.

The present invention is an apparatus for performing electrophoretic sample injection, and an object of the present invention is to provide a water-wipe injection apparatus that suppresses electrophoresis and is capable of injecting a sample into a carrier using only electroosmotic flow. be.

(Means for Solving the Problems) In the present invention, before sample injection, a conductive member is placed over the end of the capillary on the sample injection side and immersed in the sample, and electrophoretic sample injection is performed using the conductive member as one electrode. .

(Function) If a conductive member is placed over the end of the capillary on the sample injection side and used as one electrode, the tip of the capillary on the sample injection side and the sample solution around it will be in the same electric field, resulting in a jump until the sample enters the capillary. electrophoresis does not occur.

(Example) FIG. 1 is a schematic view showing a capillary electrophoresis apparatus to which the present invention is applied, and FIG. 2 is an enlarged sectional view showing the vicinity of the end of the capillary on the sample injection side of one example in a sample injection state.

In FIG. 1, 2 is added through a fused silica capillary to perform i-material injection or electrophoresis. A UV detector, for example, is provided as a detector 6 on the cathode side of the capillary 2 . FIG. 1 shows a state in which a sample is being injected, and a capillary 8 is fitted into the capillary end (anode end) on the sample injection side of the capillary 2 so as to cover the tip of the key pillar 2. The collar '8 is made of metal such as copper, and is formed into a cylindrical shape that is fitted into the butt end of the capillary 2 to cover the tip of the capillary 2. The collar 8 is attached to the bottom of the collar 8.
is connected to the anode side of the high voltage power source 4 using a clip, for example. Reference numeral 16 denotes a buffer solution for immersing the capillary anode end and anode to perform electrophoresis after sample injection.

Next, the operation of this embodiment will be explained.

When injecting a sample, attach the collar 8 to the tip of the sample injection side of the capillary 2 in advance, and then
A buffer solution is filled in the collar 8, and the collar 8 is connected to the anode of the high voltage power source 4 and immersed in the sample 10. The cathode end of the capillary 2 and the cathode 14 are immersed in the buffer solution 12. In this state, when a migration voltage is applied between both ends of the capillary 2, electrophoretic sample injection is performed.

In this case, since the collar 8 provided at the end of the capillary on the sample injection side acts as an electrode, the electric field of the sample solution around it becomes uniform. Therefore, electrophoresis does not occur in the sample sucked in by the electroosmotic flow until it reaches the tip of the capillary. Since the sample undergoes electrophoresis after entering the capillary 2, the composition differs in each part of the capillary 2, but the composition of the sample entering the capillary 2 is maintained as a whole.

After injecting the sample into capillary 2,
The collar 8 is removed from the capillary, the anode end of the capillary 2 and the anode are immersed in the buffer solution 16, and electrophoretic analysis is performed as usual.

(Effects of the Invention) In the present invention, when injecting a sample into a capillary, a conductive member is placed between the capillaries on the sample injection side, and the sample is injected using this as an anode, thereby realizing electrophoretic sample injection without any change in composition. be able to. In the case of a sample with poor conductivity, if the capillary tip and electrode are separated from each other as in conventional methods, the potential difference between them becomes large, and the potential difference varies depending on the positional relationship between the capillary tip and the electrode, resulting in variations in the electrophoresis voltage. However, the reproducibility of the analysis deteriorates.
In the present invention, since this voltage drop is small and constant, the electrophoresis voltage can be applied efficiently and with good reproducibility.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a capillary electrophoresis device in a sample injection state in one embodiment, Fig. 2 is an enlarged sectional view showing the vicinity of the anode end of the capillary in the same embodiment, and Fig. 3 is a capillary in a conventional method. FIG. 3 is a diagram showing the vicinity of the anode end. 2... Capillary, 4... High voltage power supply, 6... Detector, 8... Collar of conductive member, 10... Sample solution , 12.16. Buffer solution, 14. Cathode. Patent applicant: Shimadzu Corporation

Claims (1)

[Claims] (1) In a capillary electrophoresis device that performs electrophoresis by applying a migration voltage between both ends of a capillary filled with an electrophoresis buffer solution, when injecting a sample, the end of the capillary on the sample injection side is covered with a conductive member. A sample injection device that performs electrophoretic sample injection by immersing the sample into a sample and using the conductive member as one electrode.