Analysis system and method employing thermal desorption and spectrometric analysis
Components resolved in time by a thermal desorption separator accumulate in a sample cell and are analyzed by electromagnetic radiation-based spectroscopic techniques.
1. A sample analysis system, comprising:
a thermal desorption separator that provides components of a sample over time;
a sample cell in which the components are at least partially integrated;
a Fourier transform infrared spectrometry system for obtaining a spectral response of the components in the sample cell;
a temperature ramp driver and a heater for raising the temperature of the thermal desorption separator over time to release components that are separated or partially separated temporally.
2. The system of claim 1 , wherein a temperature ramp profile applied by the driver to the heater is optimized based on the flow characteristics of the sample cell and an operation of the spectrometry system.
3. The system of claim 1 , further comprising a sample cell heater.
4. The system of claim 1 , further comprising an output director switch for drawing vapors from the thermal desorption separator into the sample cell.
5. The system of claim 1 , further comprising one or more of: a carrier gas source, an input director switch, valves, flow controllers, vacuum pump, or pressure monitors.
6. The system of claim 1 , wherein the sample cell is a multiple path cell.
7. The system of claim 1 , wherein the thermal desorption separator is a two-stage device including a thermal desorption tube and a focusing trap.
8. The system of claim 1 , wherein the sample cell is a flow cell in which a residence time of compounds in the flow cell is similar to a length of time chemicals elute from the thermal desorption separator.
9. The system of claim 1 , wherein the system does not include a gas chromatography separation column.
10. The system of claim 1 , wherein a distance between the thermal desorption separator and the sample cell is minimized.
11. A sample analysis method, comprising:
desorbing components in a sample collected in a thermal desorption separator, wherein the desorbed components are separated or partially separated temporally using a temperature ramp driver and a heater for raising the temperature of the thermal desorption separator to release components;
directing the desorbed components to a sample cell;
allowing the components in the sample cell to become at least partially integrated; and
obtaining a spectral response of the components in the sample cell with a Fourier transform infrared spectrometry system.
12. The method of claim 11 , wherein the temporally separated components are generated by ramping the temperature of the thermal desorption separator in a linear or step-wise mode by operation of the temperature ramp driver and the heater.
13. The method of claim 11 , wherein the sample components are desorbed temporally according to their boiling points.
14. The method of claim 11 , wherein the desorbed components are not passed through a gas chromatography separation column.
15. The method of claim 11 , further comprising heating the sample cell.
16. The method of claim 11 , further comprising passing a carrier gas through the thermal desorption separator.
17. The method of claim 11 , wherein no carrier gas is passed through the thermal desorption separator.
18. The method of claim 11 , wherein the sample contains volatile organic compounds, semi-volatile organic compounds and/or nearly non-volatile organic compounds.
19. The method of claim 11 , wherein the sample cell is a flow cell in which a residence time of compounds in the flow cell is similar to a length of time chemicals elute from the thermal desorption separator.
20. The method of claim 11 , wherein the sample cell is operated in a flow-through mode or is sealed to allow components to accumulate in the sample cell.
21. The method of claim 11 , wherein the path length in the sample cell is increased by a multiple path optical arrangement.
22. The method of claim 11 , wherein the components in the sample cell are identified by periodically determining spectral responses of the components in the sample cell and using some of the spectral responses as backgrounds to analyze more recent spectral responses.
23. A sample analysis system, comprising:
a thermal desorption separator that provides multiple components of a sample to a sample cell over time;
a temperature ramp driver and a heater for raising the temperature of the thermal desorption separator over time to release components that are separated or partially separated, wherein components with different boiling points are released to the sample cell at different time; and
a Fourier transform infrared spectrometry system for obtaining a spectral response of the components that are at least partially integrated in the sample cell.
24. The system of claim 23 , wherein a temperature ramp profile applied by the driver to the heater is optimized based on the flow characteristics of the sample cell and an operation of the spectrometry system.
25. The system of claim 23 , wherein the thermal desorption separator is a two-stage device including a thermal desorption tube and a focusing trap.
26. The system of claim 23 , wherein the sample cell is a flow cell in which a residence time of compounds in the flow cell is similar to a length of time chemicals elute from the thermal desorption separator.
27. A sample analysis method, comprising:
temporally desorbing multiple components in a sample collected in a thermal desorption separator, wherein the components are separated or partially separated by raising the temperature of the thermal desorption separator according to a temperature ramp profile;
releasing the desorbed components to a sample cell, wherein components with different boiling points are released at different time;
allowing the components in the sample cell to become at least partially integrated; and
obtaining a spectral response of the components in the sample cell with a Fourier transform infrared spectrometry system.