Method for identification and quantification of siloxanes in gaseous stream

1. A method for detecting siloxanes, the method comprising:

collecting a sample in a thermal desorption tube;

passing a purge gas through the thermal desorption tube prior to desorbing siloxanes;

then raising the temperature of the thermal desorption tube desorbing the siloxanes from the thermal desorption tube;

separating the siloxanes by gas chromatography in a column; and

analyzing the siloxanes separated by gas chromatography with a Fourier Transform Infrared Spectrometry system.

2. The method of claim 1 , wherein siloxanes are desorbed from the sample by heating to a temperature of at least 200° C.

3. The method of claim 1 , wherein the Fourier Transform Infrared Spectrometry system includes a sample cell configured in a multiple path optical arrangement.

4. The method of claim 1 , wherein the purge gas is nitrogen or wherein the purge gas removes CO 2 , light hydrocarbons, water, or any combination thereof.

5. The method of claim 1 , wherein the Fourier Transform Infrared Spectrometry system identifies and quantifies individual siloxanes.

6. The method of claim 1 , wherein the sample is collected from a biogas stream or from a gas stream found in semiconductor processing.

7. The method of claim 1 , wherein the sample is collected by drawing gas from a gas stream into the thermal desorption tube using a pump.

8. The method of claim 1 , wherein the siloxanes include one or more of hexamethyldisiloxane (L2); octamethyltrisiloxane (L3); decamethyltetrasiloxane (L4 hexamethylcyclotrisiloxane (D3); octamethylcyclotetrasiloxane (D4); decamethylcyclopentasiloxane (D5); dodecamethylcyclohexasiloxane (D6).

9. A system for detecting siloxanes, the system comprising:

a thermal desorption tube connected to a gas stream that contains siloxanes;

a gas chromatography system for separating siloxanes desorbed from the thermal desorption tube; and

a Fourier Transform infrared Spectrometry system for identifying and quantifying the siloxanes separated by the gas chromatography system;

wherein a purge gas is passed through the thermal desorption tube prior to raising a temperature of the thermal desorption tube and desorbing the siloxanes.

10. The system of claim 9 , wherein the Fourier Transform Infrared Spectrometry system includes a sample cell configured in a multiple path optical arrangement.

11. The system of claim 9 , further comprising a pump for drawing gas from the gas stream into the thermal desorption tube.

12. The system of claim 9 , wherein the gas stream is a biogas stream or a gas stream found in semiconductor processing.

13. The method of claim 1 , wherein the thermal desorption tube is raised to a temperature range of about 20° C. to 40° C. while passing the purge gas through the sample desorption tube.

14. The method of claim 13 , wherein the thermal desorption tube is thereafter raised to a temperature of over 200° C., to flash desorb the siloxanes onto the column.

15. The system of claim 9 , wherein the thermal desorption tube is raised to a temperature range of about 20° C. to 40° C. while passing the purge gas through the sample desorption tube.

16. The system of claim 15 , wherein the thermal desorption tube is thereafter raised to a temperature of over 200° C., to flash desorb the siloxanes onto the column.