JPH065228B2 - Atmospheric pressure ionization type sample introduction device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an atmospheric pressure ionization type sample introduction device that vaporizes and ionizes a liquid sample under atmospheric pressure and introduces it into a vacuum chamber of a mass spectrometer, and in particular, The present invention relates to an atmospheric pressure ionization type sample introduction device suitable for realizing stable ionization by using it as an interface connecting a liquid chromatograph and a mass spectrometer.

[Background of the Invention]

The conventional technique will be described with reference to FIG. In this method, liquid samples separated by a liquid chromatograph (hereinafter referred to as LC) are sequentially put into an atmospheric pressure ionization type sample introduction device, where vaporization and ionization are performed, and a mass spectrometer (hereinafter This is an example of measuring the mass spectrum of a sample by sending it into a vacuum chamber (referred to as MS) [“Journal of Chr
omato-graphy. ”Vol 99 , p13, 1974]. In Fig. 1, the liquid sample separated and sent out by the LC is passed through the stainless pipe 1 and has an inner diameter of several mm within the atmospheric pressure ionized sample introduction chamber. Once dropped on the glass pipe 18, the glass pipe 18 is heated by the heater 13 so that the liquid sample is vaporized there and pushed by the carrier gas (nitrogen, helium, argon, etc.) 17 to the right in the figure. And is ionized under atmospheric pressure at the corona discharge needle electrode 9, part of which is introduced into the MS vacuum chamber through the pores 11 and subjected to mass spectrometry, and sample molecules and solvents that do not enter the pores. Molecules are designed to exit through the excess gas escape port 12.

However, the above conventional configuration has the following problems. That is, in the conventional configuration, the liquid sample from the LC is granular from the tip of the stainless steel pipe 1 and drops onto the heating glass pipe 18 for the first time, and then it is vaporized for the first time. However, there was a problem that the vaporization was not carried out due to the mixture of Since large liquid particles destabilize the corona discharge in the atmospheric pressure ionization method, glass wool 16 is placed in the middle of the glass pipe 18 to prevent the movement of large particles. Had a problem of deteriorating the directivity of gas. In addition, there was the problem of sample mixing due to glass wool contamination.

[Object of the Invention]

The object of the present invention is to solve the above-mentioned problems in the prior art, and to perform smooth vaporization and stable ionization under atmospheric pressure. Particularly, in combination with LC, it is sequentially separated and output from LC. An object of the present invention is to provide an atmospheric pressure ionization-type sample introduction device suitable for successively taking in liquid samples that come in, vaporizing and ionizing them, and introducing them in sequence to the vacuum chamber side of the MS.

[Outline of Invention]

The feature of the present invention is that in an atmospheric pressure ionized sample introduction device of a system in which a liquid sample is vaporized and led to an ion source chamber where it is ionized under atmospheric pressure and sent to a vacuum mass spectrometer through pores. A heat source is provided in the part to heat the liquid sample injected from one end in a temperature-controllable manner to vaporize it and eject it as a mist-like jet stream from the other end. It is configured to be connected to the ion source chamber.

Example of Invention

An embodiment of the present invention will now be described with reference to FIG.
It will be described with reference to the drawings. 2 and 3, 1 is a stainless steel pipe having an inner diameter of 0.1 mm and an outer diameter of 0.3 mm, one end of which is connected to the LC so as to capture the liquid sample separated and output from the LC. The other end is welded to the end of a copper pipe 2 having an inner diameter of about 8 mm and an outer diameter of about 10 mm, and the nichrome wire 4 wound around the insulating pipe 3 in close contact with the stainless steel pipe 1 heats it up to about 400 ° C. You can do it. As another heating method of the stainless steel pipe 1, as shown in FIG.
It is also possible to apply silver brazing inside and heat the copper block 14 with the cartridge heater 15 or the nichrome wire. In any case, the temperature of the stainless steel pipe 1 is controlled by the thermocouple 5 to be adjustable. The liquid sample output from the LC and taken into the stainless steel pipe 1 is partially vaporized while passing through the heating part of the stainless steel pipe 1,
It becomes a mist-like jet stream from the other end and jets into the air under atmospheric pressure. Stainless steel pipe 1 has an inner diameter of 0.
Since a 1 mm thin tube is used, large particles are not mixed in the mist-like vaporized sample that is ejected, and since the thin tube is used, the directivity in the ejection direction of the vaporized sample is good. At this time, the temperature of the stainless steel pipe 1 is usually set in the range of 150 ° C. to 300 ° C., depending on the type of sample passing through, and the sample is vaporized. In this way, the stainless steel pipe 1
Since there is a function of heating and vaporizing a liquid sample and a function of ejecting into the air as a jet stream without mixing large particles in the vaporized sample, there is an upper limit to the inner diameter dimension. According to the experimental results, when the inner diameter was 0.15 mm or less, large particles were not mixed in the ejected mist-like jet stream. When the inner diameter was made larger than the above, it was observed that large particles began to be mixed in the fog droplets, the directivity in the ejection direction also began to deteriorate, and the heat capacity of the heater required for heating was also reduced by the pipe diameter. It was confirmed that the larger the value, the larger the uniformity of the temperature distribution in the sample moving direction. There is no lower limit to the inner diameter, and the thinner the better, the better. However, it is determined by the pipe processing technology and the economical efficiency to make the inner diameter uniform.

The vaporized sample ejected from the end of the stainless steel pipe 1 is sent by the carrier gas 17 and first passes through the glass pipe 6 provided integrally with the ion source chamber 8 where the particle size of the fog droplets is further increased. To be smaller. A nichrome wire 7 for heating is wound around the glass pipe 6, but a cylindrical ceramic heater pipe can also be adopted for this. The fog droplets that have become smaller in size while passing through the glass pipe 6 are located in the ion source chamber 8 that is adjacent to the MS by the pores 11.
to go into. The temperature of the ion source chamber 8 is maintained at the same level as the heating temperature of the glass pipe 6 or slightly lower. A heater 13 heats the ion source chamber 8, and a ceramic heater or a cartridge heater is used. The vaporized sample introduced into the ion source chamber 8 is ionized under atmospheric pressure by the electric field applied to the needle electrode for corona discharge, and a part of it is introduced into the mass spectrometric section in vacuum through the pores 11 to generate a mass. The spectrum is measured. The tip of the needle electrode 9 is processed so that the radius of curvature is about 10 μm, and the tip portion is arranged immediately before the pore 11. The needle electrode 9 is electrically insulated from the ion source chamber 8 by an insulator 10. Excess vaporized sample or carrier gas that does not enter the pores 11 goes out through the excess gas escape port 12.

As described above, according to the apparatus of the embodiment, when the vaporized sample is introduced into the ion source chamber kept at the atmospheric pressure, it is possible to introduce it as a mist-like jet stream having a small particle size with good directivity. Therefore, stable ionization under atmospheric pressure can be realized. Especially when used in combination with LC, liquid samples sequentially separated and output from LC are sequentially captured, vaporized and ionized, and captured. MS in order
It is possible to efficiently send the data to the user side, and it is possible to greatly improve the MS analysis efficiency.

It should be noted that, in the embodiment, the liquid sample was described as being sent to the MS side in combination with LC, but when a single liquid sample is directly taken into the stainless pipe and sent to the MS side, the same operation as in the above embodiment is performed, Of course, the same effect can be produced.

〔The invention's effect〕

As described above, according to the present invention, since the vaporized sample is heated and vaporized by using the thin tube having the inner diameter of 0.15 mm or less, the vaporized sample entering the ion source chamber does not contain large particles. Stable ionization under atmospheric pressure can be achieved. Especially, when used in combination with a liquid chromatograph, various liquid samples that are separated and output are sent to the mass spectrometer side in that order one after another. It is possible,
The analysis efficiency can be significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a conventional example, and FIGS. 2 and 3 are sectional views showing an embodiment of the present invention. <Description of symbols> 1 ... Stainless steel pipe 2 ... Copper pipe 3 ... Insulation pipe 4, 7 ... Nichrome wire 5 ... Thermocouple 6 ... Glass pipe 8 ... Ion source chamber 9 ... Corona discharge needle electrode 10 ... Insulator 11 ... Pore 12… Excess gas escape port 13… Heater 14… Copper block 15… Cartridge heater 16… Glass wool 17… Carrier gas 18… Glass pipe

Claims (1)

[Claims] 1. A liquid sample is vaporized, and the vaporized sample is introduced into an ion source chamber at atmospheric pressure adjacent to a vacuum chamber of a mass spectrometer through a pore, and the corona discharge needle is placed in the ion source chamber. Temperature control is possible in an atmospheric pressure ionization type sample introduction device in which an electric field is applied to electrodes to ionize the vaporized sample, and the ionized sample is taken into the vacuum chamber of the mass spectrometer through the pores. A metal pipe having an inner diameter of 0.15 mm or less with a first heating source provided on the outer peripheral portion, and the liquid sample injected from one end of the metal pipe is heated by the first heating source to produce the metal. A sample atomizing unit that atomizes and ejects from the other end of the pipe, and a second atomizing unit that further vaporizes the atomized sample ejected from the sample atomizing unit.
And a sample vaporization section having a hollow space provided with a heating source, the other end of the metal pipe is directly opened to the sample vaporization section, and the sample vaporization section is provided with a third heating source. Connected to the ion source chamber, the sample atomizing unit, the sample vaporizing unit, and the ion source chamber are connected in a linearly continuous manner. .