JP2009133661A - Liquid chromatograph mass analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a rise in operation cost at the same time while suppressing the production of polymer in an interface part in LC/MS using an acetonitrile-containing moving phase solvent. <P>SOLUTION: LC/MS is constituted by providing a gas supply means capable of changing over a state that the same species of gases are supplied as a nebulizer gas and a drying gas from a plurality of gas sources 41 and 42 and a state that different species of gases are respectively supplied. By this constitution, even in the case where it is necessary to use synthetic air in order to suppress the production of the polymer, synthetic air is used only in the nebulizer gas low in consumption quantity and more inexpensive nitrogen can be used in the drying gas much in consumption quantity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid chromatograph mass spectrometer (hereinafter referred to as LC / MS) having an atmospheric pressure ionization interface.

  In LC / MS combining a liquid chromatograph and a mass spectrometer, an interface for ionizing a liquid flowing out from the column of the liquid chromatograph is provided at the front stage of the mass spectrometer. As an ionization method at the interface, an atmospheric pressure chemical ionization method or an electrospray ionization method in which a liquid is atomized and heated under atmospheric pressure and then ionized using a corona discharge or a high electric field is widely used.

FIG. 3 shows a schematic configuration of a conventional LC / MS with a focus on the interface portion.
In the figure, reference numeral 2 denotes a vacuum chamber for housing a mass analyzer (the configuration is omitted since it is not directly related to the present invention), and reference numeral 1 denotes an interface portion connected thereto. The interface unit 1 includes an atmospheric pressure ionization chamber 6, an ionization probe 10 inserted toward the inside thereof, and an ion introduction capillary 8 that guides an ionized sample to the vacuum chamber 2. The atmospheric pressure ionization chamber 6 and the vacuum chamber 2 are separated from each other by a partition wall 5, and the both chambers are communicated with each other through an ion introduction capillary 8 provided on the partition wall 5.

The liquid (column eluate) containing the sample separated by the liquid chromatograph unit 3 is introduced into the ionization probe 10 via the pipe 23. The configuration and operation inside the ionization probe 10 are described in Patent Document 1 and will not be described in detail here. However, the liquid introduced into the probe is nebulized gas (a spray gas, which is supplied via a pipe 22). The sample components are ionized and are blown into the atmospheric pressure ionization chamber 6 from the tip of the probe together with the vaporized solvent. The ions of the sample components are guided to the vacuum chamber 2 through the ion introduction capillary 8 and used for mass analysis. At this time, the drying gas blown out from the drying gas outlet 9 into the atmospheric pressure ionization chamber 6. Desolvation of ions is further promoted by (also referred to as desolvent gas or dry gas).
The drying gas and the nebulization gas are supplied from the common gas source 41 to the interface unit 1 through the pipes 21 and 22 with the flow rates controlled by the flow control valves 31 and 32, respectively.

  Nitrogen is generally used as the nebulizing gas and the drying gas. When the mobile phase solvent contains acetonitrile in the liquid chromatograph unit 3, a corona discharge needle (not shown) provided at the tip of the ionization probe 10 is used. ), Etc., and the sensitivity may become unstable. This is because radicals are formed by corona discharge in a nitrogen atmosphere, and this causes a polymerization reaction so that the polymer adheres to the corona discharge needle. In the presence of oxygen, oxygen and radicals combine to become inert substances. Since the polymerization reaction does not occur, it is known that this problem can be solved by mixing oxygen with the nebulization gas (see, for example, Patent Document 1).

JP 2001-43826 A

In the case where acetonitrile is contained in the mobile phase solvent, a gas (synthetic air) in which a predetermined ratio of oxygen is mixed with nitrogen is conventionally used as a nebulizing gas and a drying gas in order to suppress polymer formation. However, since synthetic air is more expensive than nitrogen, it has been a problem that the operating cost is increased.
The present invention has been made in view of such circumstances, and in LC / MS using a mobile phase solvent containing acetonitrile, an object of the present invention is to suppress an increase in operating cost while suppressing generation of a polymer in an interface part. And

  In order to solve the above problems, the present invention can switch between a state in which the same kind of gas is supplied as a nebulizing gas and a drying gas from a plurality of gas sources having different gas types and a state in which different types of gases are supplied. The LC / MS is configured with a gas feeding means. This makes it possible to use synthetic air only for nebulization gas with low consumption and use cheaper nitrogen for drying gas with high consumption even when it is necessary to use synthetic air to suppress polymer formation. .

  The present invention also comprises an LC / MS comprising gas feeding means for mixing a plurality of types of gases selected from a plurality of gas sources at a predetermined ratio and feeding them as nebulizing gas and / or drying gas. Thereby, nitrogen and oxygen can be prepared, and these can be appropriately mixed and used as a nebulizing gas and / or a drying gas, so there is no need to use expensive synthetic air.

  Since the present invention is configured as described above, the consumption of expensive synthetic air can be suppressed, or it is not necessary to use it at all, so that the operating cost of LC / MS can be reduced.

The LC / MS apparatus provided by the present invention has the following characteristics. In other words, the first feature is that a plurality of gas sources having different gas types are provided, and the second feature is that the same kind of gas is supplied as the nebulizing gas and the drying gas, and different types of gases are used. It is the point which comprised so that the gas supply means which can switch the state to supply was provided.
Therefore, the basic configuration of the best mode is an LC / MS apparatus having the above two characteristic configurations.

FIG. 1 shows an embodiment of the present invention. In the figure, since the same reference numerals as those in FIG. 3 are the same as those in FIG. 3, the description thereof is omitted here. This embodiment differs from the prior art in that nitrogen and synthetic air are provided as the two types of gas sources 41 and 42, respectively, and these two types of gas can be switched and used by the three on / off valves 45 to 47. It is a point.
With such a configuration, when the mobile phase solvent does not contain acetonitrile, the on / off valves 45 and 47 are opened and the on / off valve 46 is closed, whereby nitrogen is supplied from the gas source 41 as both the nebulizing gas and the drying gas. . When the mobile phase solvent contains acetonitrile, the on / off valves 45 and 46 are opened and the on / off valve 47 is closed, whereby synthetic air is supplied from the gas source 42 as the nebulizing gas and nitrogen is supplied from the gas source 41 as the drying gas. .

  In order to prevent the polymer from adhering to the corona discharge needle (not shown) provided at the tip of the ionization probe 10, it is sufficient if oxygen exists in the vicinity of the corona discharge needle. Can sufficiently suppress the polymer formation. Since the flow rate of the nebulizing gas is 1 to 2 L / min with respect to the flow rate of the drying gas of 10 to 20 L / min, the use of the synthetic air only for the nebulizing gas as described above reduces the consumption of expensive synthetic air to 1/10. It can be suppressed to the extent.

  If it is necessary to further increase the polymer production suppression effect, it is possible to send synthetic air to both the nebulizing gas and the drying gas by opening the on / off valves 46 and 47 and closing the on / off valve 45 in FIG. is there. However, in this case, the effect of suppressing the consumption of the synthetic air cannot be obtained.

  FIG. 2 shows another embodiment of the present invention. In the figure, since the same reference numerals as those in FIG. 3 are the same as those in FIG. 3, the description thereof is omitted here. This embodiment is different from the conventional one in that nitrogen and oxygen are provided as the two types of gas sources 41 and 43, and both are mixed by combining nitrogen and oxygen whose flow rates are controlled by the flow control valves 32 and 33. This is the point that the ionization probe 10 is supplied as nebulization gas.

In such a configuration, if the flow control valves 32 and 33 are appropriately set, nebulization gas containing oxygen having a desired concentration can be supplied, so that it is not necessary to use synthetic air. When acetonitrile is not included in the mobile phase solvent, that is, when it is not necessary to mix oxygen with the nebulization gas, the flow control valve 33 may be closed.
In the above description regarding the second embodiment, nitrogen is always used as the drying gas. However, as shown by the dotted line in FIG. It is also possible to supply a drying gas containing.

  The present embodiment has advantages over the first embodiment in that it does not require expensive synthetic air and that the oxygen concentration in the nebulization gas can be freely adjusted. Since the required concentration of oxygen in the nebulization gas varies depending on the acetonitrile concentration in the mobile phase solvent, according to this example, polymer formation can be effectively suppressed by appropriately setting the oxygen concentration.

As described above, the required concentration of oxygen in the nebulization gas varies depending on the acetonitrile concentration in the mobile phase solvent. Therefore, in the configuration of FIG. 2, a set value of an appropriate oxygen concentration corresponding to the acetonitrile concentration in the mobile phase solvent in advance. May be stored in a control device (not shown) as a program, and a nebulization gas having an optimum oxygen concentration may be automatically supplied in accordance with a signal from the control device.
In addition, when performing a gradient liquid supply in which the acetonitrile concentration in the mobile phase solvent gradually changes during the analysis, the oxygen concentration in the nebulization gas is changed over time by linking the gradient liquid supply program and the oxygen concentration setting program in the nebulization gas. It may be changed as desired.

In the above description, acetonitrile is exemplified as a solvent that causes polymer formation, and oxygen is exemplified as a substance that suppresses the reaction. However, the application of the present invention should not be limited to these, and is similar to the above substances. Of course, the present invention can be applied to other substances exhibiting the following behavior.
In addition, the number of substances that suppress the above reaction is not limited to one, and the number of gas sources 41 and the like can be increased by selecting and using a plurality of substances or mixing a plurality of substances. The present invention can be applied.

  The present invention can be used for LC / MS.

It is a figure which shows one Example of this invention. It is a figure which shows the other Example of this invention. It is a figure which shows the conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Interface part 2 Vacuum chamber 3 Liquid chromatograph part 5 Bulkhead 6 Atmospheric pressure ionization room 8 Ion introduction capillary 9 Drying gas outlet 10 Ionization probe 21 Pipe 22 Pipe 23 Pipe 31 Flow control valve 32 Flow control valve 33 Flow control valve 34 Flow control valve 41 Gas source 42 Gas source 43 Gas source 45 On-off valve 46 On-off valve 47 On-off valve

Claims (5)

A liquid chromatograph unit and a mass spectrometer unit are connected via an interface unit, and a nebulizing gas for spraying the liquid sent from the liquid chromatograph unit and a drying gas for promoting the vaporization of the solvent in the sprayed liquid In a liquid chromatograph mass spectrometer configured to supply gas from a gas source toward the interface unit, the gas source includes a plurality of gas sources having different gas types, and the nebulization gas and the drying gas A liquid chromatograph mass spectrometer comprising gas supply means capable of switching between a state in which different types of gas are supplied and a state in which the same kind of gas is supplied as the nebulizing gas and the drying gas. The liquid chromatograph mass spectrometer according to claim 1, wherein in the state where different gases are supplied as the nebulizing gas and the drying gas, a mixed gas of oxygen and nitrogen is used as the nebulizing gas and nitrogen is used as the drying gas. A liquid chromatograph unit and a mass spectrometer unit are connected via an interface unit, and a nebulizing gas for spraying the liquid sent from the liquid chromatograph unit and a drying gas for promoting the vaporization of the solvent in the sprayed liquid In the liquid chromatograph mass spectrometer configured to feed the gas source from the gas source toward the interface unit, the gas source includes a plurality of gas sources having different gas types, and the gas source is selected from the plurality of gas sources. A liquid chromatograph mass spectrometer comprising gas feeding means for mixing a plurality of kinds of gases mixed at a predetermined ratio and feeding them as the nebulizing gas and / or the drying gas. 4. The liquid chromatograph mass spectrometer according to claim 3, further comprising gas supply means capable of changing a gas mixing ratio in accordance with a predetermined program. The liquid chromatograph mass spectrometer according to claim 4, wherein the program is linked to a mobile phase gradient liquid feeding program in the liquid chromatograph section.

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