Method and apparatus for analyzing hydrocarbon streams
View Patent ↗The present invention is a method and apparatus for identifying a mixture of particles using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). The particles are first reacted in a charge exchange reaction within the FT-ICR MS chamber using ionic partners that are chosen to discriminate among components of the mixture based on ionization potential. Mass spectra of test runs using different ionic partners may then be compared to identify components based on information gathered about both molecular mass and ionization potential.
1. An apparatus for identifying components of a sample mixture, the components having respective ionization potentials defining a range of ionization potentials, the apparatus comprising:
a chamber;
at least one inlet with a sample injection valve opening to the chamber for introducing pulses of the sample mixture and of first and second reagent gasses;
excitation plates in the chamber for inducing orbital motion of ionized components within the chamber;
detecting plates for detecting the ionized components in the chamber;
an electron source for directing electrons into the chamber;
a controller configured to control the sample injection valve, the excitation plates, the detection plates and the electron source; the controller including a computer readable medium with executable instructions for performing the steps of introducing a pulse of first reagent gas through the inlet, ionizing the first reagent gas by actuating the electron source; admitting a pulse of the sample mixture through the inlet and ionizing the sample mixture through a charge exchange reaction with the ionized reagent gas, inducing an orbital motion with the excitation plates and detecting orbiting molecules with the detection plates, and repeating steps using the second reagent gas.
2. The apparatus of claim 1 , wherein the ionization potential of the first reagent gas is about 9.3 electron volts.
3. The apparatus of claim 2 , wherein the first reagent gas is selected from the group consisting of pyridine, nitrogen oxide and 1,2 difluorobenzene.
4. The apparatus of claim 1 , wherein the executable instructions further include the step of controlling a gas introduction pulse size of the sample injection valve to introduce the sample mixture into the chamber at a pressure less than 10–6 torr.
5. The apparatus of claim 1 , wherein the executable instructions further include the step of controlling a gas introduction pulse size of the sample injection valve such that the orbiting molecules are detected at a pressure less than 10–9 torr.
6. The apparatus of claim 1 , wherein the ionization potential of the second reagent gas is greater than about 14 electron volts.
7. The apparatus of claim 6 , wherein the second reagent gas is selected from the group consisting of CO, N2 and SiF4.
8. The apparatus of claim 1 , wherein the second reagent gas has an ionization potential greater than that of each of the components of the sample mixture.
9. The apparatus of claim 1 , wherein the executable instructions further include the step of comparing results obtained in the detection of the orbiting molecules produced with the first reagent gas with those produced with the second reagent gas.
10. The apparatus of claim 9 , wherein the step of comparing results obtained in the detection of the orbiting molecules produced with the first and second reagent gasses includes using results obtained in the detection of the orbiting molecules produced with the first reagent gas, to identify components appearing in the results obtained in the detection of the orbiting molecules produced with the second reagent gas.
11. The apparatus of claim 9 , wherein the step of comparing results includes identifying a component of the mixture based on information from the results from the detection steps and using an ionization potential of the component.