# US 11,029,292 B2 · Method for identification and quantification of siloxanes in gaseous stream

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- Number: US 11,029,292 B2
- Document ID: US11029292B2
- Status: Granted
- Kind: B2
- Application number: 16/095,900
- Filed: 2017-04-07
- Published: 2019-05-09
- Granted: 2021-06-08
- Earliest claimed: 2016-04-08
- Assignees: Mls Acq, Inc.
- Applicants: MLS ACQ, Inc.
- Inventors: Martin L. Spartz; Charles Mark Phillips; Peter P. Behnke; Anthony S. Bonanno
- Web page: https://patentgrep.com/patent/US11029292B2

## CPC

- G01N 30/74: Optical detectors {(measurement of intensity, velocity, spectral content, polarisation, or phase of infrared, visible or ultraviolet light G01J)}
- G01N 21/3504: for analysing gases, e.g. multi-gas analysis
- G01N 30/12: by evaporation
- G01N 30/88: Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- G01N 2021/3595: {using FTIR}
- G01N 2030/128: {Thermal desorption analysis}
- G01N 2030/743: {FTIR}
- G01N 2030/884: {organic compounds}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A method and system for detecting siloxanes using thermal desorption tubes and FTIR spectrometers with intervening gas chromatography systems.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

The method of claim 1, wherein the purge gas is nitrogen or wherein the purge gas removes CO2, light hydrocarbons, water, or any combination thereof.

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

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

### Claim 7 (depends on 1)

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.

### Claim 8 (depends on 1)

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).

### Claim 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.

### Claim 10 (depends on 9)

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

### Claim 11 (depends on 9)

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

### Claim 12 (depends on 9)

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

### Claim 13 (depends on 1)

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.

### Claim 14 (depends on 13)

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.

### Claim 15 (depends on 9)

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.

### Claim 16 (depends on 15)

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.