JP2011013055A - Liquid chromatograph mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove soot attached around a spray 22 by adjusting an introduction amount of an organic solvent, a heating temperature and the like according to physical properties such as a melting point of an analyzing object without decomposing an ionized interface for an APCI.SOLUTION: A soot remover 41 is attached at the time of soot removing operation. Only nebulizer gas is blown out of a spray 22 without spraying a liquid sample, and the nebulizer gas blown out is sprayed to a hollow stick electrode 43. The nebulizer gas sprayed to the hollow stick electrode 43 flows backward into the spray 22, and removes the soot attached around the spray 22 from a sprayed portion to float it. The floated soot is caught by static electricity generated in the hollow pin electrode 43. In analysis, the remover 41 is detached.

Description

  The present invention relates to a liquid chromatograph mass spectrometer (hereinafter referred to as “LC-MS”), and more particularly to a mechanism for removing soot generated and remaining in an interface of an atmospheric pressure chemical ionization method (APCI).

In LC-MS, which combines a liquid chromatograph (LC) and a mass spectrometer (MS), a liquid sample flowing out from an LC column is vaporized, and a dedicated interface is used to ionize the target component while removing the solvent. Face is used. Such an interface generates gas ions by atomizing a liquid sample by heating, high-speed air flow, high electric field, etc., and atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) are the most popular. Widely used.

In APCI, a compound to be analyzed is sprayed in an atomization chamber together with an organic solvent such as methanol, and the atomization chamber is heated by a heater, thereby vaporizing them by gas spraying and heating. A corona needle is disposed in the atomization chamber, and a high voltage is applied to the corona needle to cause a corona discharge, thereby ionizing the vaporized organic solvent and ions between the organic solvent ion and the analyte compound. The compound to be analyzed is ionized by a molecular reaction.

  The introduction amount of the organic solvent and the optimum value of the heating temperature of the heater are determined according to physical properties such as the melting point of the analysis object. When the interface is used under a condition where the absolute amount of the organic solvent is large and the heating temperature is high, soot may be generated in a part of the introduced organic solvent.

JP-A-11-213175

Soot generated under the above conditions remains inside the interface and adheres around the gas outlet. As a result, the gas outlet is clogged, causing a failure of the interface, or remaining soot is detected as a contaminating component in the later analysis, which hinders the analysis result. Conventionally, the soot treatment of the interface has been performed by disassembling the interface itself and wiping the soot-attached portion with a clean cloth or the like, but the time required for this is estimated to be about 60 to 120 minutes. Is very time consuming.

Although not used in the LC-MS interface, as a general soot removal technique, exhaust gas components are captured by a method or filter that oxidizes exhaust gas components using a catalyst such as platinum and removes soot. Method of removing by collecting and burning (Diesel
Particulate Filter). However, the former is effective for components that are molecularized among exhaust gas components, but there is a problem that the effect is low for components having a large size such as soot, and the latter is independent of the size of exhaust gas components. Although effective removal is possible, there is a problem that the size of the exhaust gas treatment device is large, and there is a problem in applying any of them as a soot treatment technology of the LC-MS interface.

  Accordingly, an object of the present invention is to provide a technique for soot processing of a small interface that does not require disassembly of the interface itself, enables highly effective soot processing.

The invention described in claim 1, which has been made to solve the above problem, is a spray unit that ejects a liquid sample and a nebulizer gas supplied from the liquid chromatograph unit between the liquid chromatograph unit and the mass spectrometer unit. And a liquid chromatograph mass spectrometer equipped with a corona needle for ionizing a liquid sample ejected from the spray unit, the nebulizer gas ejected from the spray unit is located in front of the spray port of the spray unit. A liquid chromatograph mass spectrometer comprising: a removable or mobile nebulizer gas backflow member for backflowing to the part; and a removable or mobile soot collection electrode located in front of the spray port of the spray part Device.

In the present invention, soot removal is performed as follows. Only the nebulizer gas is ejected from the spray unit without spraying the liquid sample. Then, when the nebulizer gas ejected from the spray section is sprayed on the nebulizer gas backflow member located in front of the spray outlet of the spray section, the nebulizer gas flows backward toward the spray section. The back-flowing nebulizer gas causes the soot adhering to the periphery of the spray port of the spray unit to separate from the spray unit and float. The floating soot is attracted to and collected by the soot collection electrode by the electric field generated from the soot collection electrode.

The invention described in claim 2 is the liquid chromatograph mass spectrometer according to claim 1, wherein the soot collection electrode serves as a nebulizer gas backflow member. It is an analysis device.

In the present invention, the soot collection electrode can serve as a nebulizer gas backflow member by installing the soot collection electrode in front of the spray outlet of the spray section.

The invention described in claim 3 is the liquid chromatograph mass spectrometer according to claim 1 or 2, wherein the corona needle and the soot collection electrode are brought into contact with each other, and the soot collection is performed. A liquid chromatograph mass spectrometer using the power source of the corona needle as an electrode power source.

  The present invention uses a single power source as a power source for a corona needle and a power source for a soot collection electrode, so that even when a soot collection electrode is provided in a conventional APCI ion source, a soot collection electrode is provided. There is no need to provide a new power supply. In this case, the corona needle power source can be connected to the soot collection electrode via the corona needle by bringing the corona needle into contact with the soot collection electrode.

The invention described in claim 4 is the liquid chromatograph mass spectrometer according to any one of claims 1 to 3, wherein the soot collection electrode is a hollow bar electrode, The liquid chromatograph mass spectrometer is characterized in that a plurality of hollow plate electrodes are arranged inside the hollow rod electrode.

  The soot that has floated away from the spray portion due to the backflowed nebulizer gas is collected by a hollow bar electrode in which a plurality of hollow plate electrodes are arranged. In this case, since a plurality of hollow plate electrodes are arranged inside the hollow rod electrode, an area capable of collecting soot is increased. In addition, since soot is collected by adhering to the inner wall of the hollow bar electrode or the hollow plate electrode, it is possible to prevent the soot once collected from leaving the soot collecting electrode again. That is, even if nebulizer gas continues to be ejected for soot removal, the hollow plate electrode prevents the nebulizer gas from spraying directly on soot, so that the inner wall of the hollow rod electrode and the soot attached to the hollow plate electrode are separated again. prevent. In addition, when the soot removal operation is completed, static electricity is not generated from the soot collection electrode, and when removing the soot collection electrode, the collected soot is deposited inside the hollow rod electrode, Since the metal plate is prevented from coming out of the soot from the hollow bar, the removal operation can be performed smoothly.

  According to the invention of claim 1, conventionally, in order to remove the soot adhering to the vicinity of the spraying port of the spray part, only the decomposition and cleaning of the ion source for APCI was performed. However, by introducing the present invention, The soot adhering to the spraying part to be analyzed / measured can be removed by being caught in the gas flow and collected.

According to the invention of claim 2, since the soot collection electrode can play the role of a nebulizer gas backflow member, it is possible to reduce the number of parts, which is excellent in terms of cost and use.

  According to the invention of claim 3, since the corona needle can be used as a power source for the soot collecting electrode, a new power source becomes unnecessary when a soot removing device is provided.

According to the invention of claim 4, it is possible to increase the soot collection area and increase the amount of soot that can be collected, and to prevent the collected soot from separating from the soot collection electrode again.

The block diagram of LC-MS which applies the soot removal apparatus of this invention. The block diagram which mounted | wore the ionization probe with the soot removal apparatus of this invention. The block diagram of the soot removal apparatus of this invention. The block diagram which mounted | wore the ionization probe with the soot removal apparatus of the deformation | transformation Example of this invention. The block diagram of the soot removal apparatus of the deformation | transformation Example of this invention.

FIG. 1 is a block diagram of an LC-MS to which the soot removal mechanism of the present invention is applied. Between the liquid chromatograph (LC) unit 10 and the mass spectrometry unit (MS) 30, the sample that has passed through the column 14 of the LC unit 10 is vaporized and ionized, and the vaporized solvent is further removed to the MS unit 30. An ionization interface 20 is provided for delivery.

In the LC unit 10, the liquid feed pump 12 sucks the solvent (mobile phase) stored in the solvent tank 11 and flows it to the column 14 at a constant flow rate. The sample injection unit 13 injects a predetermined amount of sample solution into the solvent. When passing through the column 14, each sample component in the sample solution is temporally separated, sequentially flows out from the outlet of the column 14, passes through the sample channel 15, and is ionized by the ionization probe 29 in the ionization interface. The nebulizer gas that has flowed out of the injection gas channel 16 sprays the liquid sample that flows out of the sample channel 15. The nebulizer gas is supplied by adjusting a predetermined gas stored in the gas cylinder 26 to a predetermined flow rate by a flow rate regulator (or pressure adjusting valve) 27.

Since soot is generated in the ionization probe 29, it is necessary to perform a soot removal operation. Therefore, when the soot removing operation is performed, the soot removing device 41 is attached to the ionization probe 29 and the soot removing operation is performed. Since the soot removing device 41 is removable, it is attached at the time of soot removing work and removed at the time of analysis for analysis. Further, since the ionization probe 29 itself can be removed from the apparatus, the soot removal operation can be performed without disassembling the ionization probe 29 by attaching the soot removal device 41 after removing the ionization probe 29 once. It becomes possible to do. Detailed description of the ionization probe 29 and the soot removing device 41 will be described later.

The analysis chamber 34 of the MS unit 30 is evacuated to a high vacuum state, and the two intermediate vacuum chambers 32 and 33 disposed between the atomization chamber 21 and the analysis chamber 34 each have a small opening. The partition is partitioned by a partition wall, whereby the degree of vacuum increases stepwise from the atomization chamber 21 toward the analysis chamber 34. As described above, the sample ions generated in the atomization chamber 21 are drawn into the intermediate vacuum chambers 32 and 33 by the differential pressure, and further drawn into the analysis chamber 34 to be a quadrupole filter 35 composed of four rod electrodes. Sent to the central space. A voltage in which an AC voltage and a DC voltage are superimposed is applied to the quadrupole filter 35, and only ions having a specific mass number (mass m / charge z) corresponding to the voltage are applied to the quadrupole filter 35. To reach the ion detector 36. In the ion detector 36, a current corresponding to the number of reached ions is taken out.

  FIG. 2 is a block diagram of the ionization interface of the present invention. The removal of soot in the present invention will be described with reference to FIG. A ceramic tube 42 is installed in front of the spray section 22 for ejecting the liquid sample flowing out from the sample channel 15 and the nebulizer gas flowing out from the jet gas channel 16, and a heater 23 is provided around the ceramic tube 42. Yes. The ceramic tube 42 and the inside thereof are heated to a high temperature, and the sample sprayed by the spray unit 22 is vaporized in the ceramic tube 42. The vaporized sample is ionized by corona discharge generated by a high voltage (approximately several kV) applied to the corona needle 25 connected to the corona discharge high-voltage power supply 28.

However, depending on the physical properties such as the melting point of the analyte, the sample may become soot depending on the amount of the organic solvent introduced, the heating temperature, etc. Moreover, the spray part 22 may be clogged.

In order to remove the soot, a detachable soot removing device 41 is attached to the ceramic tube 42. The soot removing device 41 is removed at the time of analysis or the like, and the removing device 41 is attached when performing the soot removing operation. The soot removing device 41 includes a hollow bar electrode 43 and is connected to a high voltage power source 44 for soot removal. Static electricity is generated in the hollow rod electrode 43.

In the soot removal operation, the liquid sample is not sprayed from the spray section 22, and only the nebulizer gas is sprayed, and the sprayed nebulizer gas is sprayed onto the hollow rod electrode 43. The hollow rod electrode 43 is hollow, but has a thickness, and therefore, a surface on which the nebulizer gas is sprayed is formed at the end of the hollow rod electrode 43. The nebulizer gas sprayed on the end face of the hollow bar electrode 43 flows backward toward the spraying part 22, and the soot adhering to the periphery of the spraying part 22 is separated from the spraying part and floats. In this case, as the position of the hollow rod electrode 43 to which the nebulizer gas is sprayed is closer to the spray portion 22, the amount of the nebulizer gas flowing back increases, and the effect of removing soot is high. The floating soot is collected by static electricity generated in the hollow bar electrode 43.

FIG. 3 is a block diagram of the soot removing device of the present invention. The soot removal will be described with reference to FIG. The soot removing device 41 includes a hollow bar electrode 43 and an attaching / detaching portion 48. The soot removing device 41 is attached to the ceramic tube 42. Since the corona needle 25 is installed around the ceramic tube 42, the soot removing device 41 can be attached to the ceramic tube 42 so as not to contact the corona needle 25. Thus, it is preferable to provide a notch 46 in the hollow rod electrode 43 and the attachment portion 48. The hollow rod electrode 43 may be made of a metal such as stainless steel.

  FIG. 4 is a block diagram of an ionization interface showing a modified embodiment of the present invention. On the inner wall of the hollow rod electrode 43 of the soot removing device 41, the hollow plate electrode 45 is arranged side by side. By adopting this shape, the hollow plate electrode 45 is soaked in the gas flow of the soot adhering in the hollow rod electrode 43 and separated from the inner wall of the hollow rod electrode 43 or the hollow plate electrode 45 again. 43 prevents soot from jumping out of the inside. Moreover, since the floating soot can be collected on the inner wall of the hollow rod electrode 43 and the front and back surfaces of the hollow plate electrode 45, the area capable of collecting soot compared to the case where the hollow plate electrode 45 is not provided. Will be able to collect more soot.

  FIG. 5 is a diagram for explaining a soot removing device 41 used in the modified embodiment. The description of the parts in common with FIG. 2 is omitted. Hollow plate electrodes 45 are arranged side by side on the inner wall of the hollow rod electrode 43. Moreover, the material of the attaching / detaching portion 48 is not particularly limited. However, if a conductive material is used for the attaching / detaching portion 48 and the corona needle 25 is brought into contact with the needle power contact 47 provided on the attaching / detaching portion 48, the corona discharge high-voltage power supply 28 is used to charge the hollow rod electrode 43. Therefore, it is not necessary to provide the high voltage power supply 44 for removing soot.

DESCRIPTION OF SYMBOLS 10 Liquid chromatograph (LC) part 11 Solvent tank 12 Liquid feed pump 13 Sample injection part 14 Column 15 Sample flow path 16 Injection gas flow path 20 Ionization interface 21 Atomization chamber 22 Spray part 23 Heater 24 Temperature sensor 25 Corona needle 26 Gas cylinder 27 Flow regulator (or pressure regulating valve)
28 High-voltage power supply for corona discharge 29 Ionization probe 30 Mass spectrometer (MS)
31 Desolvation tubes 32 and 33 Intermediate vacuum chamber 34 Analysis chamber 35 Quadrupole filter 36 Ion detector 41 Soot removal device 42 Ceramic tube 43 Hollow rod electrode 44 High voltage power supply 45 for soot removal Hollow plate electrode 46 Notch 47 Corona needle contact

Claims (4)

Between the liquid chromatograph part and the mass spectrometric part, a liquid sample provided from the liquid chromatograph part and a spray part for ejecting a nebulizer gas, and a corona needle for ionizing the liquid sample ejected from the spray part are provided. In a liquid chromatograph mass spectrometer,
A detachable or movable nebulizer gas backflow member that is located in front of the spray outlet of the spray section and reverses the nebulizer gas ejected from the spray section to the spray section,
A liquid chromatograph mass spectrometer comprising a detachable or movable soot collection electrode positioned in front of the spray outlet of the spray section. In the liquid chromatograph mass spectrometer according to claim 1,
A liquid chromatograph mass spectrometer characterized in that a soot collection electrode serves as a nebulizer gas backflow member. In the liquid chromatograph mass spectrometer according to claim 1 or 2,
Contacting the corona needle and the soot collection electrode;
A liquid chromatograph mass spectrometer using a power source for the corona needle as a power source for the soot collection electrode. The liquid chromatograph mass spectrometer according to any one of claims 1 to 3, wherein the soot collection electrode is a hollow bar electrode, and a plurality of hollow plate electrodes are provided inside the hollow bar electrode. A liquid chromatograph mass spectrometer characterized by being arranged.

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