Method and system for sampling and determining the presence of compounds

• US 5,567,623 A
• Filed: 04/04/1995
• Issued: 10/22/1996
• Est. Priority Date: 06/01/1992
• Status: Expired due to Term

• Current Assignee: The Coca-Cola Company
• Original Assignee: The Coca-Cola Company
• Inventors: Rounbehler, David P., Fine, David H., MacDonald, Stephen J., Achter, Eugene K., Dennison, Daniel B.
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): FREED, RACHEL
• Application Number:
  US08/416,574
• Time in Patent Office: 567 Days
• Field of Search: 436/106, 436/108, 436/111-113, 436/116, 436/117, 436/118, 436/139, 436/140, 436/172, 436/158, 436/159, 436/160, 436/152-153, 436/52, 436/53, 422/78, 422/80, 422/83, 422/93, 422/98, 422/82.08
• US Class Current: 436/158
• CPC Class Codes: B07C 5/34 Sorting according to other particular properties material testing per se G01N; quality control G07C3/14
• CPC Class Codes: B07C 5/3408 for bottles, jars or other glassware according to size B07C5/122
• CPC Class Codes: B08B 2203/005 the liquid being ozonated
• CPC Class Codes: B08B 9/46 Inspecting cleaned containers for cleanliness
• CPC Class Codes: B29B 17/00 Recovery of plastics or other constituents of waste material containing plastics; volume reduction of waste plastics, e.g. by mechanical compacting or melting disposal of solid waste B09B; chemical recovery C08J11/00
• CPC Class Codes: B29B 17/02 Separating plastics from other materials
• CPC Class Codes: B29B 2017/0275 using chemical sensors, e.g. analysing gasified constituents
• CPC Class Codes: G01N 1/2202 involving separation of sample components during sampling
• CPC Class Codes: G01N 1/2226 Sampling from a closed space, e.g. food package, head space
• CPC Class Codes: G01N 1/24 Suction devices G01N1/22 - G01N1/2294 take precedence
• CPC Class Codes: G01N 2001/2223 aerosol sampling devices
• CPC Class Codes: G01N 2001/2229 Headspace sampling, i.e. vapour over liquid
• CPC Class Codes: G01N 21/64 Fluorescence; Phosphorescence
• CPC Class Codes: G01N 21/76 Chemiluminescence; Bioluminescence
• CPC Class Codes: G01N 21/766 of gases
• CPC Class Codes: G01N 21/9018 Dirt detection in containers
• CPC Class Codes: G01N 33/0081 Containers; Packages; Bottles
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling
• CPC Class Codes: Y10T 436/113332 with conveyance of sample along a test line in a container or rack
• CPC Class Codes: Y10T 436/17 Nitrogen containing
• CPC Class Codes: Y10T 436/206664 : Ozone or peroxide
• CPC Class Codes: Y10T 436/21 : Hydrocarbon

Abstract

A system and method are provided for minimizing the effects of background signals in masking signals indicating the presence of substances to be detected such as contaminants in materials moving rapidly along a conveyor. The contaminants detected may include nitrogen containing compounds and hydrocarbons. The system and method of the present invention minimizes the number of falsely positive indications of the presence of such substances due to background signals and changes in background signals. The substances detected are divided into first and second sample portions and the respective portions are heated. The first heated portion is reacted with ozone to generate radiation by chemiluminescence having characteristic wavelengths related to substances in the first portion. The second portion heated is also reacted with ozone to generate radiation by chemiluminescence having characteristic wavelengths related to substances in the second portion. The radiation of the respective first and second portions is selectively detected. The heating and detecting steps are performed in a manner so as to yield a higher level of detected radiation from one of the portions of the sample then the other for at least some of the selected compounds being detected. Electrical signals from the respective first and second portions are generated and compared in order to determine the presence or absence of selected compounds in the sample. Appropriate reject signals for a bottle sorting system are generated accordingly.

Claims

1. A method of detecting selected compounds in a sample by chemiluminescent gas phase reaction with a reactant comprising the steps of:

collecting the sample;

dividing the sample into first and second portions;

heating the first portion of the sample to a first predetermined temperature in a first pyrolyzer having first conversion properties with respect to the selected compounds;

heating the second portion of the sample to a second predetermined temperature in a second pyrolyzer having second conversion properties with respect to the selected compounds which are different from the first conversion properties of the first pyrolyzer;

mixing the heated first portion of the sample with the reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to substances in said first portion;

mixing the heated second portion of the sample with the reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to substances in said second portion;

selectively detecting radiation emitted by chemiluminescence from a selected compound in the first portion of the sample;

selectively detecting radiation emitted by chemiluminescence from conversion of the selected component in the second portion of the sample and at least the same compound in the first portion of the sample in the second portion of the sample;

generating first electrical signals from the radiation selectively detected from the first portion of the sample and second electrical signals from the radiation selectively detected from the second portion of the sample; and

comparing the first electrical signals with the second electrical signals in order to determine the presence or absence of selected compounds in the sample;

wherein said heating, mixing, detecting, and generating steps are performed at substantially the same times for said first portion as for said second portion and wherein the step of comparing includes the steps of comparing the first electrical signals and the second electrical signals so as to cancel signals related to said portions of background components.

2. The method of claim 1 wherein said first pyrolyzer is formed from ceramic materials and the second pyrolyzer is formed from nickel materials.

3. The method of claim 1 including the further steps of comparing each of the first and second electrical signals individually with second predetermined threshold criteria.

4. The method of claim 1 wherein said dividing step is performed in a manner to yield substantially equal portions of the sample.

5. The method of claim 1 wherein said heating steps performed in said first and second pyrolyzers such that each is heated to substantially the same temperature in the range of about 800°

to 1000°

C.

6. The method of claim 1 wherein the result of the comparing step is further compared to a first predetermined threshold criteria.

7. A system for detecting selected compounds in a sample by chemiluminescent gas phase reaction with a reactant comprising:

means for collecting the sample;

means for dividing the sample into first and second portions;

first converter means for hearing the first portion of the sample to a first predetermined temperature, said first converter means having first conversion properties with respect to the selected compounds;

second converter means for heating the second portion of the sample to a second predetermined temperature, said second converter means having second conversion properties with respect to the selected compounds which are different from the first conversion properties of the first converter means;

means for mixing the heated first portion of the sample with the reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to substances in said first portion;

means for mixing the heated second portion of the sample with the reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to substances in said second portion;

means for selectively detecting radiation emitted by chemiluminescence from a selected compound of the first portion of the sample;

means for selectively detecting radiation emitted by chemiluminescence from the conversion of selected compounds and at least the same compound in the first portion in the second portion of the sample;

means for generating first electrical signals having amplitudes and durations related to the detected characteristic wavelengths of radiation emitted from the mixed first portion of the sample and second electrical signals having amplitudes and durations related to the detected characteristic wavelengths of radiation emitted from the mixed second portion of the sample; and

means for comparing the first electrical signals with the second electrical signals in order to determine the presence or absence of selected compounds in the sample;

said heating, mixing, detecting, and generating means being operable to process said first portion at substantially the same relative times as the processing of said second portion to thereby permit cancellation of signals related to background components from said first and second electrical signals by said comparing means.

8. The system of claim 7, wherein the first converter means has a heating chamber including ceramic materials and the second converter has a heating chamber including nickel materials.

9. The system of claim 7 wherein the means for comparing is operable to subtract the first electrical signals from the second electrical signals and to compare the net result to predetermined threshold criteria.

10. The system of claim 9 further including means for comparing each of the first and second electrical signals individually with predetermined threshold criteria.

11. A method of detecting selected compounds in a sample by chemiluminescent gas phase reaction of a compound which might be present as a background component of the sample, and as a converted product of one of said selected compounds, with a chemical reactant comprising the steps of:

collecting the sample;

dividing the sample into first and second portions;

heating the first portion of the sample to a first predetermined temperature in a first pyrolyzer having a first conversion properties such that no appreciable amounts of the compound in the background component can be produced thereby conversion of the selected components;

heating the second portion of the sample to a second predetermined temperature in a second pyrolyzer having second conversion properties such that the measurable amounts of the compound from the background component, and also from converted products of the selected compounds can be produced;

mixing the heated first portion of the sample with said chemical reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to a compound of the background component in said first portion;

mixing the heated second portion of the sample with said chemical reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to the background component of the compound, and the compound produced by conversion of the selected compounds in said second portion;

selectively detecting radiation emitted by chemiluminescence from the background component in the first portion of the sample;

selectively detecting radiation emitted by chemiluminescence from the converted products of the selected compounds in the second portion of the sample as well as said background components in the second portion;

generating first electrical signals from the radiation selectively detected from the first portion of the sample and second electrical signals from the radiation selectively detected from the second portion of the sample; and

comparing the first electrical signals with the second electrical signals in order to determine the presence or absence of selected compounds in the sample;

wherein said heating, mixing, detecting, and generating steps are performed at substantially the same times for said first portion as for said second portion and wherein the step of comparing includes the steps of comparing the first electrical signals with the second electrical signals so as to cancel signals related to said compound in the background component in said portions.

12. The method of claim 11 wherein said first pyrolyzer is formed from ceramic materials and said second pyrolyzer is formed from nickel materials.

13. The method of claim 11 including the further steps of comparing each of the first and second electrical signals individually with second predetermined threshold criteria.

14. The method of claim 11 wherein said dividing step is performed in a manner to yield substantially equal portions of the sample.

15. The method of claim 11 wherein said heating steps are performed in first and second converters each heated to substantially the same temperature in the range of about 800°

to 1000°

C.

16. The method of claim 11 wherein the result of the comparing step is further compared to a first predetermined threshold criteria.