SPECTROSCOPIC BREATH ANALYSIS

• US 20080064975A1
• Filed: 11/06/2007
• Published: 03/13/2008
• Est. Priority Date: 08/16/2001
• Status: Abandoned Application

• Current Assignee: Graham Hancock, Grant Ritchie, Robert Peverall
• Original Assignee: Graham Hancock, Grant Ritchie, Robert Peverall
• Inventors: Ritchie, Grant, Hancock, Graham, Peverall, Robert
• Application Number:
  US11/935,518
• Publication Number:
  US 20080064975A1
• Time in Patent Office: Days
• US Class Current: 600/532
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: G01N 21/39 using tunable lasers
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath
• CPC Class Codes: H01J 49/04 Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components

Abstract

Methods and apparatus for the analysis of exhaled breath by spectroscopy are disclosed. An optical cavity containing the exhaled breath, typically comprising a pair of opposing high reflectivity mirror, is used to implement a cavity enhanced absorption technique. Pairs of ¹²CO₂ and ¹³CO₂ absorption lines suitable for use in spectroscopic breath analysis are also disclosed.

Claims

1-22. -22. (canceled)

23. A method of using cavity enhanced absorption spectroscopy to quantify one or more isotopically-labelled carbon compounds in a sample, the method comprising the steps of:

passing at least a portion of said sample into an optical cavity;

illuminating said sample in said optical cavity with radiation emitted by an optical source, wherein the optical cavity is arranged to allow radiation emitted from the optical source to be repeatedly reflected and retrace its path to excite a plurality of cavity modes; and

measuring a wavelength-dependent reduction in the intensity of radiation in said optical cavity caused by variations in cavity ringdown time caused by absorption of said radiation in said optical cavity by said one or more isotopically-labelled carbon compounds, thereby to quantify said one or more isotopically-labelled carbon compounds.

33. A method of using cavity enhanced absorption spectroscopy to quantify one or more nitrogen compounds in a sample, the method comprising the steps of:

passing at least a portion of said sample into an optical cavity;

illuminating said sample in said optical cavity with radiation emitted by an optical source, wherein the optical cavity is arranged to allow radiation emitted from the optical source to be repeatedly reflected and retrace its path to excite a plurality of cavity modes; and

measuring a wavelength-dependent reduction in the intensity of radiation in said optical cavity caused by variations in cavity ringdown time caused by absorption of said radiation in said optical cavity by said one or more nitrogen compounds, thereby to quantify said one or more nitrogen compounds.

36. A method of using cavity enhanced absorption spectroscopy to quantify isotopically-labelled water in a sample, the method comprising the steps of:

passing at least a portion of said sample into an optical cavity;

illuminating said sample in said optical cavity with radiation emitted by an optical source, wherein the optical cavity is arranged to allow radiation emitted from the optical source to be repeatedly reflected and retrace its path to excite a plurality of cavity modes; and

measuring a wavelength-dependent reduction in the intensity of radiation in said optical cavity caused by variations in cavity ringdown time caused by absorption of said radiation in said optical cavity by said isotopically-labelled water, thereby to quantify said isotopically-labelled water.

38. A method of using cavity enhanced absorption spectroscopy to detect the presence of bacteria in a sample, the method comprising the steps of:

contacting said sample with a metabolizable compound;

collecting gas produced by said sample;

passing at least a portion of said gas into an optical cavity;

illuminating said gas in said optical cavity with radiation emitted by an optical source, wherein the optical cavity is arranged to allow radiation emitted from the optical source to be repeatedly reflected and retrace its path to excite a plurality of cavity modes; and

measuring a wavelength-dependent reduction in the intensity of radiation in said optical cavity caused by variations in cavity ringdown time caused by absorption of said radiation in said optical cavity by metabolites of said compound, thereby to detect the presence of said bacteria.

44. A method of using cavity enhanced absorption spectroscopy to detect the presence in a sample of at least one compound indicative of one of:

explosives, nerve gas, natural gas deposits, and oil deposits, the method comprising the steps of;

passing at least a portion of said sample into an optical cavity;

illuminating said gas in said optical cavity with radiation emitted by an optical source, wherein the optical cavity is arranged to allow radiation emitted from the optical source to be repeatedly reflected and retrace its path to excite a plurality of cavity modes; and

measuring a wavelength-dependent reduction in the intensity of radiation in said optical cavity caused by variations in cavity ringdown time caused by absorption of said radiation in said optical cavity by said at least one compound, thereby to perform said detection.