Detection system and method

• US 4,778,764 A
• Filed: 10/07/1974
• Issued: 10/18/1988
• Est. Priority Date: 10/07/1974
• Status: Expired due to Term

• Current Assignee: Thermedics, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Thermedics, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Fine, David H.
• Primary Examiner(s): Marcus, Michael S.
• Application Number:
  US05/512,374
• Time in Patent Office: 5,125 Days
• Field of Search: 23/230 PC, 23/253 PC, 73/23.1, 210/198 C, 422/42-52, 422/89, 422/78, 422/80, 436/114-116, 436/161, 436/122, 436/124, 436/172
• US Class Current: 436/116
• CPC Class Codes: G01N 2030/025 Gas chromatography
• CPC Class Codes: G01N 2030/8405 using pyrolysis
• CPC Class Codes: G01N 30/84 Preparation of the fraction to be distributed
• CPC Class Codes: G01N 31/12 using combustion G01N25/20 takes precedence
• CPC Class Codes: Y10T 436/176152 Total nitrogen determined
• CPC Class Codes: Y10T 436/177692 Oxides of nitrogen
• CPC Class Codes: Y10T 436/186 Sulfur dioxide
• CPC Class Codes: Y10T 436/19 Halogen containing

Abstract

A detection system for detecting the presence of predetermined compounds in a sample. The system comprises a sample injection means, a chromatographic column, a conversion means and one or more specific gas detectors. The conversion means transforms the column effluent to combustion products in the gas phase, after which those combustion products are transferred to the specific gas detectors. In one embodiment for detecting nitrogen compounds, the conversion means includes an oxygen-rich flame, a means to control the flame to have a temperature in the range 600°-1700° C., means to inject the column effluent into the flame, and an output port for transferring the flame effluent to a specific nitrogen detector.

Claims

1. A chromatographic detection system comprising, in combination:

A. a gas chromatograph having a chromatograph output port,

B. a nitric oxide (NO) gas detector having a detector input port, means for reacting combustion products with ozone (O₃), and means for detecting light having wavelength in the range 0.6-2.8 microns, and

C. a convertor including;

i. an input port connected to said chromatograph output port having means to inject effluent from said chromatograph into said convertor,

ii. conversion means to convert said injected effluent into said combustion products, said combustion products being in the gas phase, and having means to control said conversion to take place at a temperature in the range 600°

-1700°

C.,

iii. a convertor output port connected to said detector input port, and

iv. means for transferring said combustion products to said detector.

2. The detection system according to claim 1 wherein said conversion means comprises a furnace having a temperature control, means to inject oxygen (O₂) into said furnace, and means to establish a pressure in said furnace in the range 5 torr to 5 atmospheres.

3. The detection system according to claim 1 wherein said conversion means comprises a means to establish a flame disposed to intercept said injected effluent.

4. A detection system according to claim 3 wherein said means to establish a flame is adapted to provide an oxygen-rich flame.

5. The detection system according to claim 3 wherein said conversion means further includes means to control the environment of said flame to be air at a pressure in the range 5 torr to 5 atmospheres.

6. A method for analysis of a sample dissolved in a gas phase solution comprising the sequential steps of:

A. passing said solution through a gas chromatograph to produce a gas phase effluent,

B. converting said effluent into combustion products in the gas phase at a temperature in the range 600°

-1700°

C.,

C. transferring said combustion products to a nitric oxide (NO) detector, and

D. detecting the presences of NO at said detector, wherein said detecting step comprises the sub-steps of reacting said combustion products with ozone (O₃), and detecting light having wavelength in the range 0.6-2.8 microns.

7. The detection means according to claim 6 wherein said converting step includes the sub-step of injecting said effluent together with oxygen into a furnace while maintaining said furnace at a pressure in the range 5 torr to 5 atmospheres.

8. The method according to claim 6 wherein said converting step includes the sub-steps of establishing a flame and injecting said effluent into said flame.

9. The method according to claim 8 wherein said flame is maintained to be oxygen-rich.

10. The method according to claim 8 wherein said flame is established in an air environment at a pressure in the range 5 torr to 5 atmospheres.