RU2529009C2 - Method of mass spectrometric analysis of gas sample in glow discharge and device for its realisation - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: invention relates to analytical instrument making and may be used in analysis of environment, identification and detection of quantity of admixtures of various chemical substances in ambient air, in technological processes, control of exhaled air in diagnostics and treatment of various diseases. The method includes creation of a glow discharge in a flow of ionising gas, supply of a flow of ionising gas together with an investigated gas sample, directed along the axis of the flow of ionising gas into a reactor, ionisation of components of the gas sample in presence of the focusing radio frequency electric field under pressure in the reactor in the range of 0.03-3 millibar, transportation of ions to a mass-analyser and mass-spectral registration of produced ions. Another aspect of the invention is a device for mass spectrometric analysis described above, comprising a source of a glow discharge, a channel for supply of ionising gas, a reactor for ionisation of gas sample components, a unit of ion transport and mass-analyser, the novelty of which consists in the fact that it additionally comprises a focusing radio-frequency ion-optic element, arranged inside the reactor along its longitudinal axis, at the same time the source of glow discharge is combined with a channel for ionising gas.

EFFECT: increased sensitivity and simplified process.

13 cl, 5 dwg

Description

The invention relates to analytical instrumentation and can be used in environmental analysis, identification and determination of the amount of impurities of various chemicals in the ambient air, in technological processes, control of exhaled air in the diagnosis and treatment of various diseases, control of the content of medications in exhaled air during operations, control of pharmaceutical products, food products, various organic substances and other objects.

A known method and device in which a sample from a column of a gas chromatograph together with a gas stream is introduced into a radio frequency glow discharge excited in He at low pressure - 0.7 Torr, where the determined volatile compounds are dissociated and ionized directly in the discharge [M.M. Wauop, CBHymer, CAPonce de Leon and JAGaruso. The use of radiofrequency glow discharge mass-spectrometry (rf-GD-MS) coupled to gas chromatography for the determination of selenoaminoacids in biological samples // Journal of Analytical Atomic Spectrometry. 2001, V. 16, P. 492-497]. At an optimal discharge power, almost complete dissociation of the analyzed compounds (in this case, selenium compounds) occurs. The use of helium rather than argon as ballast gas allows one to get away from the influence of polyatomic ions ( ⁴⁰ Ar ⁴⁰ Ar ⁺ and others) on the analysis results.

A disadvantage of the known technical solutions is the limited information received - information about the structure of organic compounds is lost, since only atomic ions are formed as a result of ionization, and information remains only on the elemental composition of the sample.

Known for the prototype method and device for mass spectrometric analysis of a gas sample in a glow discharge, in which the method comprises creating a glow discharge in a stream of ionizing gas, transporting the ionizing gas through an air conditioner to the reactor, introducing a previously prepared gas sample into the ionizer of the mass spectrometer, ionizing the components samples, transportation of ions to the mass analyzer, and mass spectral registration of ions (A.Verentchikov, A.Zamyatin // Mass spectrometer with soft ionizing glow discharge and conditioner // International patent application WO 2012/024570, Priority date 08.19.20 10, Published 02.23.2012).

A device for implementing this method includes a sequentially arranged glow discharge unit, a channel for an ionizing gas, the dimensions of which allow the separation of fast electrons from atoms and ions of a glow discharge, the introduction of a test gas sample, and a reactor in which the pressure of -30 mbar is required to realize method, ion transport unit and mass analyzer.

However, the proposed technical solutions require complex technological solutions to provide the required vacuum when transporting ions from the reactor to the mass analyzer (pumping); powerful vacuum pumps are needed. In addition, the loss of sample ions when they are transported to the mass analyzer simply by a gas stream reduces the sensitivity of the method, the information content of the obtained mass spectra is informative, and thereby limit the analytical capabilities of gas mass spectrometry.

The task of the invention is to expand the analytical capabilities of gas mass spectrometry while simplifying the process.

The problem is achieved in that the method of mass spectrometric analysis of a gas sample in a glow discharge includes creating a glow discharge in a stream of ionizing gas, supplying a stream of ionizing gas along with the gas sample to be studied into the reactor, ionizing the components of the gas sample in the reactor, transporting ions to the mass analyzer and mass spectral registration of the resulting ions. In this case, the novelty lies in the fact that the ionization of the components of the gas sample is carried out in the presence of a focusing radio-frequency electric field, while the pressure in the reactor is maintained in the range of 0.03-3 mbar, and the gas sample stream is introduced along the axis of the flow of ionizing gas from the glow discharge.

The simplest technical solution is to create a focusing radio-frequency electric field with four parallel symmetrically arranged electrodes, while a radio-frequency voltage with opposite signs is applied to both pairs of opposite electrodes.

The easiest way is to create a focusing radio frequency electric field using a quadrupole.

When creating a focusing radio-frequency electric field using a quadrupole to remove unwanted ions from the reactor, the ionization of the components of the gas sample is carried out by applying an additional periodic alternating electric field to the focusing radio-frequency field:

,

,

where t is the time

- амплитуда напряженности дополнительного поля в области ионизации,

- the amplitude of the additional field in the ionization region,

,and the oscillation frequency of the additional field Ω is in accordance with m / q of the excluded ion by the formula $$\Omega =\frac{\sqrt{2}{U}_0}{\left(m/q\right)\mathrm{<figure-callout\; id="0"\; label="\omega \; R"\; filenames="00000023.png,00000024.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}{R}_{}^{}{}_0^2}$$

,

where U ₀ is the amplitude, ω is the frequency of the main sinusoidal radio frequency voltage supplied to the rods of the quadrupole,

R ₀ is the radius of the circle inscribed in the quadrupole,

a m and q are the mass and charge of the removed ions, respectively.

6. The method according to claim 3, characterized in that to remove several groups of ions with different m / q, the ionization of the components of the gas sample is carried out by applying an additional periodic alternating electric field to the focusing radio frequency field of the quadrupole:

,

,

- амплитуда напряженности каждой компоненты,Where

- the amplitude of the tension of each component,

t is the time

для m/q каждого из ионов,Ω ₁ ... - Ω _n are the resonant oscillation frequencies of the ions selected for exclusion, determined by the formula $$\Omega =\frac{\sqrt{2}{U}_0}{\left(m/q\right)\mathrm{<figure-callout\; id="0"\; label="\omega \; R"\; filenames="00000023.png,00000024.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}{R}_{}^{}{}_0^2}$$

for m / q of each of the ions,

where U ₀ is the amplitude, ω is the frequency of the main sinusoidal radio frequency voltage supplied to the rods of the quadrupole,

R ₀ is the radius of the circle inscribed in the quadrupole,

a m and q are the mass and charge of the removed ions, respectively.

It is desirable to create a glow discharge in the flow of ionizing gas without contact with the electrodes.

It is most technologically advanced to direct the flow of ionizing gas from a glow discharge along the longitudinal axis of the reactor.

To increase the efficiency of extraction of ions from the reactor, it is desirable to maintain the pressure of the ionizing gas in the reactor in the range of 0.01-3 mbar.

To increase the sensitivity of the analysis by reducing the adsorption of sample molecules in the inlet line, it can be heated to a temperature of 200-250 ° C before the gas sample is fed into the reactor.

To increase the sensitivity of the analysis, it is desirable to separate it from the air before supplying the gas sample to the reactor.

Another aspect of the invention is the mass spectrometric analysis apparatus described above, consisting of a glow discharge source, an ionizing gas supply channel, a reactor for ionizing gas sample components, an ion transport unit and a mass analyzer, the novelty of which is that it additionally contains a focusing radio-frequency ion-optical element located inside the reactor along its longitudinal axis, while the source of the glow discharge is combined with the channel for ionizing gas.

As focusing radio-frequency ion-optical elements, any element from the series can be selected: a quadrupole. sextupole, octupole, set of coaxial metal diaphragms, ion funnel.

To improve ion focusing, the reactor further comprises a direct current ion optic unit located between the focusing radio frequency ion-optical element and the outlet of the reactor.

The most technologically advanced is the implementation of an ion transport block from sequentially arranged elements of direct current ion optics and radio frequency optics elements.

The use of a focusing radio frequency field in mass spectrometric analysis of a gas sample is known. However, these elements were previously used either to increase the efficiency of transporting ions from the reactor to the mass analyzer (for which they were located between them), or as a mass analyzer, for analyzing the masses of ions from any external ion source and obtaining a mass spectrum.

We were the first to propose placing a focusing radio-frequency ion-optical element in a reactor and ionizing the components of a gas sample in the presence of a focusing radio-frequency electric field under the claimed conditions

The technical result in this case will be to increase the sensitivity of mass spectrometric analysis, increase the information content of the obtained mass spectra, and simplify the process by reducing the vacuum pumping power required to implement the method.

Analysis of the known technical solutions allows us to conclude that the invention is not known from the prior art, which indicates its compliance with the criterion of "novelty."

The essence of the present invention for specialists does not follow explicitly from the prior art, which allows us to conclude that it meets the criterion of "inventive step".

The possibility of carrying out the method with the achievement of the task indicates that the invention meets the criterion of "industrial applicability".

Figure 1 presents a block diagram of the proposed device;

Figure 2 shows two mass spectra of a gas sample when introducing a gas sample at the inlet of the reactor along the axis of the flow of ionizing helium gas from a glow discharge: (A) the mass spectrum of the gas sample from the air in the laboratory room, (B) the mass spectrum air from the laboratory room, which added 5 ppm of hexane;

Figure 3 shows the mass spectrum of a gas sample of air in a laboratory room with 5 millionths of hexane, obtained in the absence of a focusing radio frequency field;

Figure 4 shows the mass spectrum of a gas sample of air from a laboratory room with 5 ppm hexane obtained with a focusing radio frequency field when a gas sample was introduced into the reactor volume perpendicular to the axis of the flow of ionizing helium gas from a glow discharge;

Figure 5 shows the mass spectrum of a gas sample of air from a laboratory room, at a gas pressure in the reactor at a level of 0.03 mbar when introducing a gas sample at the inlet to the reactor.

The device for mass spectrometric analysis consists of a source of glow discharge 1, combined with a channel for supplying ionizing gas 2, a reactor for ionizing the components of the gas sample 3, in front of which there is an input 4 of the test gas sample, the ion transport unit 5 and the mass analyzer 6 Inside the reactor 3 along its longitudinal axis is a focusing radio-frequency ion-optical element 7, which can be selected from any of the following elements: a quadrupole (Fig. 1), sextupole, octupole, a set of coaxial metallic female diaphragms, ion funnel. A focusing radio-frequency ion-optical element 7 is connected to a radio frequency voltage unit 8.

To improve ion focusing, the reactor may further comprise a direct current ion optic unit 9, to which a constant potential is applied, slightly higher than the potential at the outlet of the reactor, and located between the focusing radio-frequency ion-optical element 7 and the outlet of the reactor 3.

The ion transport unit 5 consists of sequentially arranged elements of direct current ion optics 10 and elements of radio frequency ion optics 11. The element of radio frequency ion optics 11 preferably contains a radio frequency multipole transport (quadrupole, sextupole, octupole), which increases the efficiency of ion transport and reduces the ionic energy spread. Reducing the energy dispersion of ions increases the resolution when registering the mass spectrum in the mass analyzer. The resulting mass spectrum is used to identify the chemical compounds contained in the test gas sample.

The device operates as follows: an ionizing gas (may be helium, argon, nitrogen, etc.) is introduced into the channel of the source of glow discharge 1. The best results are obtained when creating a glow discharge in the flow of ionizing gas without contact with the electrodes, while channel 1 is made from dielectric material. The flow of ionizing gas, having passed the glow discharge zone, transfers active particles from the glow discharge through channel 2 to reactor 3, i.e. ionizing gas ions, electrons and highly excited molecules / atoms of the ionizing gas. The pressure in the reactor 3 is maintained in the range of 0.03-3 mbar, and the flow of the gas sample through the inlet 4 is introduced along the axis of the flow of ionizing gas from the glow discharge. It is advisable to heat the inlet 4 to a temperature of 200-250 ° C before feeding the gas sample into the reactor 3, which gives a decrease in the adsorption of sample molecules in the input line and, accordingly, an increase in the sensitivity of the method.

To increase the sensitivity of the analysis, before the gas sample is fed into the reactor 3, it is separated from the air by passing the gaseous sample through a chromatograph (not shown in FIG. 1).

In the reactor 3, a gas sample in a stream of ionizing gas enters the radio frequency field of the ion-optical element 7 located here. Using a radio frequency voltage unit 8, a sinusoidal radio frequency voltage is supplied to both pairs of opposite electrodes of the ion-optical element 7. When expanding the gas sample along the axis of the flow, the radio-frequency field of the ion-optical element 7 does not allow them to scatter, but holds it, collects it on the axis of the reactor and ensures efficient extraction of ions into the outlet of the reactor 3.

Free electrons penetrate weakly into the region inside the ion-optical element 7, which creates a radio frequency field, and therefore the energy transfer to the formed sample ions decreases, and the intensity of the molecular ions of the sample (M-H) + in the mass spectrum increases. Thus, the analytical characteristics of the device are increased, because molecular ion, unlike fragmentation ions, is characteristic of a particular chemical compound. As a result, with an increase in the relative intensity of the molecular ion, the detection limit of chemical compounds in the sample decreases and the reliability of identification of chemical compounds in the sample increases.

For a more selective removal of undesirable ions from the reactor 3, the ionization of the components of the gas sample is carried out by applying an additional periodic alternating electric field to the focusing radio frequency field of the quadrupole 7 using the radio frequency voltage unit 8:

,

,

where t is the time

- амплитуда напряженности дополнительного поля в области ионизации,

- the amplitude of the additional field in the ionization region,

,and the oscillation frequency of the additional field Ω is in accordance with m / q of the excluded ion by the formula $$\Omega =\frac{\sqrt{2}{U}_0}{\left(m/q\right)\omega {\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="00000023.png,00000024.png"\; state="\{\{state\}\}">R</figure-callout>}}_0^2}$$

,

where U ₀ is the amplitude, ω is the frequency of the main sinusoidal radio frequency voltage supplied to the rods of the quadrupole,

R ₀ is the radius of the circle inscribed in the quadrupole,

a m and q are the mass and charge of the removed ions, respectively.

6. The method according to claim 3., characterized in that to remove several groups of ions with different m / q, the ionization of the components of the gas sample is carried out by applying an additional periodic alternating electric field to the focusing radio frequency field of the quadrupole:

,

,

- амплитуда напряженности каждой компоненты,Where

- the amplitude of the tension of each component,

t is the time

для m/q каждого из ионов,Ω ₁ ... - Ω _n are the resonant oscillation frequencies of the ions selected for exclusion, determined by the formula $$\Omega =\frac{\sqrt{2}{U}_0}{\left(m/q\right)\omega {\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="00000023.png,00000024.png"\; state="\{\{state\}\}">R</figure-callout>}}_0^2}$$

for m / q of each of the ions,

where U ₀ , is the amplitude, ω is the frequency of the main sinusoidal radio frequency voltage supplied to the rods of the quadrupole,

R ₀ is the radius of the circle inscribed in the quadrupole,

a m and q are the mass and charge of the removed ions, respectively.

The creation of an additional alternating field with the frequency of the resonant vibrations of one excluded ion or the sum of several alternating fields with frequencies corresponding to the resonant frequencies of the excluded ions makes it possible to selectively exclude ions in the vicinity of one or more selected m / q values. Thus, it is possible to selectively exclude or weaken the channels of ionization reactions in which excluded ions are involved, and to keep light ions with small m / q in the mass spectrum that carry important analytical information.

Thus, the use of the supply of additional alternating voltage to the ion-optical element 7 in the reactor 3 allows you to further expand the functionality of the claimed device for mass spectrometric analysis. For example, in the mass spectrum, the ions formed as a result of the proton transfer reaction are attenuated or lost, the intensity of the ions formed as a result of ionization by the excited particles of the ionizing gas increases, and the shape of the resulting mass spectrum is simplified, which simplifies the identification of compounds in the composition of the gas sample.

The examples below confirm, but do not limit, the proposed technical solutions.

и с примесью 5 ppm гексана $$\underset{\_}{Б}$$

подают в реактор вдоль оси потока ионизирующего газа из тлеющего разряда. Поддерживаем с помощью насоса давление в реакторе 1 миллибар. Получаем масс-спектры $$\underset{\_}{А}$$

и $$\underset{\_}{Б}$$

, приведенные на фиг.2. Масс-спектр Б по сравнению с масс-спектром А имеет интенсивный пик (M-H)⁺ состава $$C_6{H}_{13}^{+}$$

, равный по интенсивности другим, осколочным ионам гексана $$C_5{H}_{11}^{+}$$

и $$C_4{H}_9^{+}$$

. Площадь пика $$C_6{H}_{13}^{+}$$

составляет более 30000, для 5 миллионных долей гексана, что соответствует пределу обнаружения по концентрации на уровне 100 триллионных долей.Example 1. We supply helium ionizing gas through a glass channel with a diameter of 4 mm, activate (turn on) a glow discharge using two electrodes located outside the channel, applying alternating voltage to them with an amplitude of about 500 V at a frequency of about 500 kHz (while a glow discharge in a stream of ionizing gas is created without contact of the ionizing gas with the electrodes). Ionizing gas enters the reactor, in which a quadrupole of 4 rods with a diameter of 5 mm is located, the diameter of the circle inscribed in the quadrupole is 5 mm. A sinusoidal radio frequency voltage with an amplitude of 20 volts and a frequency of 1 MHz is supplied to pairs of opposite rods of the quadrupole. Two air samples from the laboratory room without impurities $$\underset{\_}{\mathrm{BUT}}$$

and mixed with 5 ppm hexane $$\underset{\_}{B}$$

fed into the reactor along the axis of the flow of ionizing gas from a glow discharge. Using a pump, we maintain a pressure of 1 millibar in the reactor. We get the mass spectra $$\underset{\_}{\mathrm{BUT}}$$

and $$\underset{\_}{B}$$

shown in figure 2. The mass spectrum B in comparison with mass spectrum A has an intense peak (MH) ^{+ of} composition $$C_6{\mathrm{<figure-callout\; id="13"\; label="H"\; filenames="00000025.png"\; state="\{\{state\}\}">H</figure-callout>}}_{13}^{+}$$

equal in intensity to other fragmentation ions of hexane $$C_5{H}_{\mathrm{eleven}}^{+}$$

and $$C_{\mathrm{four}}{H}_9^{+}$$

. Peak area $$C_6{\mathrm{<figure-callout\; id="13"\; label="H"\; filenames="00000025.png"\; state="\{\{state\}\}">H</figure-callout>}}_{13}^{+}$$

is more than 30,000, for 5 ppm of hexane, which corresponds to the detection limit by concentration at the level of 100 trillion fractions.

Example 2. The same as in example 1, only the process is carried out in the absence of a sinusoidal radio frequency field in the ionization zone of the analyzed sample. The mass spectrum (Fig. 3) of a gas sample of air with 5 ppm hexane obtained with the quadrupole off, shows that the intensity of both molecular (MH) ⁺ and fragment hexane peaks is approximately 50 times lower than for the case of ion focusing the radio frequency field of the quadrupole (figure 2).

Example 3. The same as in example 1, only the process is carried out by introducing a gas sample perpendicular to the axis of the helium flow from a glow discharge. The voltage parameters applied to the radio-frequency quadrupole were the same as for the mass spectrum in figure 2. In the mass spectrum of a gas sample of air with 5 ppm hexane, shown in Fig. 4, it is seen that the intensity of the obtained peak of the molecular ion hexane (MH) ⁺ is 10 times less than for the case of introducing a gas sample along the axis of the flow of ionizing gas from the smoldering discharge (figure 2).

Example 4. The same as in example 1, only the process is carried out when changing the pressure of the gas maintained in the reactor by adjusting the flow of the gas sample and vacuum pumping the volume of the reactor. In this case, the dependence of the set of ionization reactions that determine the composition of the ions of the gas sample in the mass spectrum was found. If the pressure in the reactor is <0.03 mbar, then the composition of the ions in the mass spectrum determines the reaction of direct ionization of the sample molecules by active particles of excited helium from a glow discharge:

He * + Π → He + Π ⁺ e ^- .

и $$O_2^{+}$$

основных компонент воздуха. В масс-спектрах на фиг.3-6, полученных при давлении в реакторе на уровне 0,7 миллибар, отсутствует пик ионов $$N_2^{+}$$

. При таком давлении ионы претерпевают большее количество столкновений в реакторе и передают заряд на молекулы пробы, например:Intensive ions are visible in the mass spectrum shown in FIG. 5, obtained by filling a gas sample and maintaining the pressure in the reactor at a level of <0.03 mbar. $${\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="00000026.png"\; state="\{\{state\}\}">N</figure-callout>}}_2^{+}$$

and $${\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="00000026.png"\; state="\{\{state\}\}">O</figure-callout>}}_2^{+}$$

major air component. In the mass spectra in figure 3-6, obtained at a pressure in the reactor at a level of 0.7 mbar, there is no peak ion $$N_{}^{}$$$${}_2^{+}$$

. At this pressure, ions undergo a greater number of collisions in the reactor and transfer the charge to the sample molecules, for example:

$${\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="00000026.png"\; state="\{\{state\}\}">N</figure-callout>}}_2^{+}+\mathrm{<figure-callout\; id="2"\; label="\Pi \; \to \; N"\; filenames="00000026.png"\; state="\{\{state\}\}">\Pi \; </figure-callout>}\to N_{}{}_2+{\Pi }^{+}$$

, $${\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="00000026.png"\; state="\{\{state\}\}">N</figure-callout>}}_2^{+}+{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="00000026.png"\; state="\{\{state\}\}">O</figure-callout>}}_2\to {\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="00000026.png"\; state="\{\{state\}\}">N</figure-callout>}}_2+{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="00000026.png"\; state="\{\{state\}\}">O</figure-callout>}}_2^{+}$$

,

, $${\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="00000026.png"\; state="\{\{state\}\}">O</figure-callout>}}_2^{+}+\mathrm{<figure-callout\; id="2"\; label="\Pi \; \to \; O"\; filenames="00000026.png"\; state="\{\{state\}\}">\Pi \; </figure-callout>}\to O_{}{}_2+{\Pi }^{+}$$

,

and. etc

At a pressure in the reactor above ~ 3 mbar, the efficiency of ion focusing by the radio-frequency field decreases by more than 10 times.

Thus, the proposed invention allows to increase the sensitivity of the analysis of gas samples by more than 50 times using standard vacuum equipment for pumping, which indicates the simplification of the process by reducing the power of vacuum pumping required to implement the prototype method. The ionization mode used also makes it possible to obtain intense molecular ions of organic compounds, which make it possible to more reliably identify the test sample and increase the information content of the obtained mass spectra.

Claims (13)

1. The method of mass spectrometric analysis of a gas sample in a glow discharge, including the creation of a glow discharge in a stream of ionizing gas, supplying a stream of ionizing gas together with the studied gas sample to the reactor, ionizing the components of the gas sample in the reactor, transporting ions to the mass analyzer and mass spectral registration of the resulting ions, characterized in that the ionization of the components of the gas sample is carried out in the presence of a focusing radio-frequency electric field, while maintaining the pressure in the reactor They range from 0.03–3 mbar, and the gas sample stream is introduced along the axis of the ionizing gas stream from the glow discharge. 2. The method according to claim 1, characterized in that the focusing radio-frequency electric field is created by four parallel symmetrically arranged electrodes, moreover, radio frequency voltage with opposite signs is applied to both pairs of opposite electrodes. 3. The method according to claim 2, characterized in that the radio frequency voltage is in the form of a sinusoid. 4. The method according to claim 3, characterized in that the focusing radio-frequency electric field is created using a quadrupole. 5. The method according to claim 4, characterized in that to remove unwanted ions from the reactor, the ionization of the components of the gas sample is carried out by applying an additional periodic alternating electric field to the quadrupole focusing radio frequency field:

,
where t is the time

- the amplitude of the additional field in the ionization region,
and the oscillation frequency of the additional field Ω is in accordance with m / q of the excluded ion by the formula $$\Omega =\frac{\sqrt{2}{U}_0}{\left(m/q\right)\omega R_0^2}$$

,
where U ₀ is the amplitude, ω is the frequency of the main sinusoidal radio frequency voltage supplied to the rods of the quadrupole,
R ₀ is the radius of the circle inscribed in the quadrupole,
am and q are the mass and charge of the removed ions, respectively. 6. The method according to claim 3, characterized in that to remove several groups of ions with different m / q, the ionization of the components of the gas sample is carried out by applying an additional periodic alternating electric field to the focusing radio frequency field of the quadrupole:

,
Where

- the amplitude of the tension of each component,
t is the time
Ω ₁ …… - Ω _n are the resonance frequencies of the oscillations of the ions selected to exclude, determined by the formula $$\Omega =\frac{\sqrt{2}{U}_0}{\left(m/q\right)\omega R_0^2}$$

for m / q of each of the ions,
where U ₀ , is the amplitude, ω is the frequency of the main sinusoidal radio frequency voltage supplied to the rods of the quadrupole,
R ₀ is the radius of the circle inscribed in the quadrupole,
am and q are the mass and charge of the removed ions, respectively. 7. The method according to claim 1, characterized in that a glow discharge in the flow of ionizing gas is created without contact of the ionizing gas with the electrodes. 8. The method according to claim 1, characterized in that before the gas sample is supplied to the reactor, it is heated to a temperature of 200-250 ° C. 9. The method according to claim 1, characterized in that to increase the sensitivity of the analysis before feeding a gas sample into the reactor, it is separated from the air. 10. A device for mass spectrometric analysis in accordance with method of claim 1, consisting of a glow discharge source, an ionizing gas supply channel, a reactor for ionizing gas sample components, an ion transport unit and a mass analyzer, characterized in that it further comprises focusing radio-frequency ion-optical element located inside the reactor along its longitudinal axis, while the source of the glow discharge is combined with the channel for ionizing gas. 11. The device according to claim 10, characterized in that as the focusing radio-frequency ion-optical elements selected elements from the series: quadrupole. sextupole, octupole, set of coaxial metal diaphragms, ion funnel. 12. The device according to claim 10, characterized in that to improve the focusing of the ions, the reactor further comprises a direct current ion optic unit located between the focusing radio-frequency ion-optical element and the outlet of the reactor. 13. The device according to claim 10, characterized in that the ion transport unit consists of successively arranged elements of direct current ion optics and elements of radio frequency ion optics.

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