Method and apparatus for sample analysis

• US 20060144126A1
• Filed: 02/18/2004
• Published: 07/06/2006
• Est. Priority Date: 01/25/2000
• Status: Active Grant

• Current Assignee: Oregon State University (Oregon University System), State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Portland State University
• Original Assignee: State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Portland State University
• Inventors: O'Brien, Robert J., Smith, Thomas R.
• Granted Patent: US 7,257,987 B2
• Time in Patent Office: Days
• US Class Current: 73/23.420
• CPC Class Codes: G01N 1/2202 involving separation of sample components during sampling
• CPC Class Codes: G01N 1/40 Concentrating samples
• CPC Class Codes: G01N 1/405 by adsorption or absorption
• CPC Class Codes: G01N 2030/025 Gas chromatography
• CPC Class Codes: G01N 2030/324 speed, flow rate
• CPC Class Codes: G01N 2030/685 flame photometry
• CPC Class Codes: G01N 21/3518 Devices using gas filter correlation techniques; Devices using gas pressure modulation techniques
• CPC Class Codes: G01N 21/51 inside a container, e.g. in an ampoule G01N21/53 takes precedence
• CPC Class Codes: G01N 30/32 of pressure or speed G01N30/36 takes precedence

Abstract

Methods and systems for analyzing samples, such as gas samples, are described. One method comprises providing a gas sample, increasing pressure applied to the gas sample to compress the sample to a smaller volume and provide a pneumatically focused gas sample, and analyzing the pneumatically focused gas sample using any of a variety of analytical techniques. Also disclosed are systems for gas analysis, including systems for analysis of pneumatically focused, and thereby concentrated, gas samples and for analysis of particulate matter in gas samples. Analytical systems constructed within personal computer cases also are disclosed.

Claims

1. A gas chromatograph and gaseous sample analysis system, comprising:

a sample loop for receiving a first volume of a gaseous sample;

a separatory column fluidly connected to and downstream of the sample loop;

an inline pressure-increasing valve downstream of the separatory column which increases system pressure to pneumatically focus the gaseous sample and reduces flow rate through the system; and

a detector downstream or upstream of the pressure increasing valve for detecting analytes.

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19. A method for selectively detecting different particles in a gas sample, comprising:

increasing the relative humidity of the gas sample at a controlled rate over a period of time; and

detecting hydration of particles in the gas sample as a function of time during the period of time over which the relative humidity is increased to selectively detect different particles in the gas sample on the basis of different times or different relative humidities at which the different particles hydrate during the period of time.

31. The method of claim 19, wherein the particles comprise spores.

32. The method of claim 31, wherein the spores are mold spores.

33. The method of claim 31, wherein the spores are anthrax spores.

57. The method of claim 31, wherein the spores comprise agglomerations of individual spores.

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37. A system for detecting particulate matter in a gas sample, comprising:

a cell having a means for introducing the gas sample into the cell and a means for compressing or expanding the sample once the sample is within the cell, the cell further comprising a first window through which a light beam may be directed into the cell and a second window for detecting the light beam or light scattered from the light beam as the light beam passes through the cell; and

a detector positioned to detect the light beam or light scattered from the light beam.

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48. An analytical instrument contained in a personal computer case.

49. The analytical instrument of claim 48, wherein the instrument is selected from the group consisting of a gas chromatograph, a pneumatic focusing gas chromatograph, a pneumatic focusing spectrophotometer, a gas chromatograph/mass spectrometer, a mass spectrometers, a particulate detection system, a fluorescence spectrophotometer and an infrared spectrophotometer.

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52. A system for concentration and analysis of a gaseous sample, comprising:

a piston for compressing the sample from a first volume to a second volume, the second volume being smaller than the first volume;

a separatory column fluidly connected to and downstream of the piston;

an inline pressure-increasing valve downstream of the separatory column which increases system pressure to pneumatically focus the gaseous sample and reduce flow rate through the system as the piston is used to compress the sample; and

a detector for detecting analytes within the sample.

53. The system of claim 52, wherein the detector is a flame-ionization detector.

54. The system of claim 52 further comprising a piston inlet assembly.

55. The system of claim 52, wherein the system is contained in a computer case.

58. The system of claim 52, further comprising a valve arrangement downstream of the separatory column which closes a high flow channel during piston compression, thereby forcing flow through a low flow channel, and opens when the sample is compressed to the second volume, thereby allowing flow to revert to the high flow channel.

56. A method for separating and analyzing components of a gas sample, comprising:

pressurizing the gas sample in a piston to provide a pneumatically focused sample at a first pressure, the first pressure being greater than a second pressure used to separate the components of the gas sample;

introducing the pneumatically focused gas sample into a separatory column at the first pressure;

reducing the pressure in the separatory column to the second pressure;

separating the components of the gas sample at the second pressure; and

detecting the separated components of the gas sample.

59. A method for analyzing a gas sample, comprising:

providing a gas sample or converting a sample to a gas sample;

increasing pressure applied to the gas sample to compress the sample to a smaller volume and provide a pneumatically focused gas sample; and

analyzing the pneumatically focused gas sample.

60. The method according to claim 59 where the gas sample is pneumatically focused concurrently with or just prior to reaching a spectrometric cell.

61. The method according to claim 59 where analyzing the pneumatically focused sample comprises reducing the pressure of the carrier-pneumatic focusing gas simultaneously with or subsequent to a pneumatically focused sample being injected onto a separatory column or a spectrometric cell.

62. The method according to claim 59 where the gas sample is pneumatically focused using a carrier gas or a compressor at a first pressure and further comprising rapidly decreasing or increasing pressure between a first and second pressure.

63. The method according to claim 62 where the first pressure is changed to the second pressure simultaneously with or subsequent to the sample being introduced to a spectrometric cell.

64. A method for analyzing an air sample, comprising:

collecting an air sample;

increasing the pressure of the sample to a pressure of from about 100 psi to about 15,000 psi to pneumatically focus the air sample; and

analyzing the pneumatically focused sample in real time using a gas chromatograph or a spectrometer.

65. The method according to claim 64 and further including reduced temperature focusing the air sample either prior to or subsequent to pneumatically focusing the sample.

66. The method according to claim 65 where reduced temperature focusing occurs in a spectrometric cell.

67. The method according to claim 65 where reduced temperature focusing is accomplished using a device upstream of a spectrometric cell.