RU2012155613A - METHOD FOR MASS-SPECTROMETRIC ANALYSIS OF A GAS SAMPLES IN A Glow DISCHARGE AND A DEVICE FOR ITS IMPLEMENTATION - Google Patents

Abstract

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 in the range 0.03–3 mbar, and the gas sample stream is introduced along the axis of the flow of ionizing gas from the glow discharge. 2. The method according to claim 1, characterized in that the focusing radiofrequency 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. The method according to claim 2, characterized in that the radio frequency voltage is in the form of a sine wave. 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 focusing radio frequency field of the quadrupole, where t is time, is the amplitude of the additional field in the ionization region, and the frequency the oscillations of the additional field

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 focusing radio frequency field of the quadrupole

, 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 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

, 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 a m 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.