WO2012121651A1 - Make up and protective gas for light path window materials and increased spatial resolution in gas chromatography - uv detection - Google Patents

Make up and protective gas for light path window materials and increased spatial resolution in gas chromatography - uv detection Download PDF

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Publication number
WO2012121651A1
WO2012121651A1 PCT/SE2012/050245 SE2012050245W WO2012121651A1 WO 2012121651 A1 WO2012121651 A1 WO 2012121651A1 SE 2012050245 W SE2012050245 W SE 2012050245W WO 2012121651 A1 WO2012121651 A1 WO 2012121651A1
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Prior art keywords
gas
light
flow
absorbing chamber
light absorbing
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PCT/SE2012/050245
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French (fr)
Inventor
Lennart Olsson
Hans Verner Lagesson
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Chromalytica Ab
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Publication of WO2012121651A1 publication Critical patent/WO2012121651A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/62—Detectors specially adapted therefor
    • G01N30/74—Optical detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light path
    • G01N2021/151—Gas blown
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
    • G01N2021/335—Vacuum UV
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/62—Detectors specially adapted therefor
    • G01N30/74—Optical detectors
    • G01N2030/746—Optical detectors detecting along the line of flow, e.g. axial

Definitions

  • the present invention relates Gas Chromatography, GC - Ultraviolet absorption, UV - spectroscopy, GC-UV, to detect, identify and analyse gases, liquids and solid known and unknown substances from high to very low
  • concentrations and is directed to a method and an apparatus for obtaining photonic signal levels and spatial resolution from samples in gas phase of substances in a first flow of gas by a first step comprising selection by time by gas chromatography and by a second step comprising absorption of photons by UV light down to 120 nm of wavelength that passes a light absorbing chamber for identification and quantification of substances.
  • the basic technology is known and used for various purposes. Such solutions are disclosed in US6305213 and US4668091 , Verner Lüsson et. al.
  • the invention relates to physical, mechanical and software control solutions.
  • the invention solves one of the major problems to achieve in order to detect absorption of very short wavelengths (typically down to 120nm) for identification of unknown substances in gas phase.
  • Gas chromatography UV - spectroscopy is used for identification and quantification of various substances that can be transformed into gas.
  • the technology is based on that substances in gas phase first passes through a heated column where the gas has a substance dependent velocity through the column and when the gas to be analyzed leaves the first heated column and enters a chamber where UV light passes the gas, absorb light when the light passes the gas, in a spectral way, so the photonic spectrum relates with very high accuracy to the identity of the substance.
  • the light used for the absorption shall preferably have a broad spectrum of wavelengths to allow absorption over a broad spectrum of wavelengths.
  • the passage, chamber, where light penetrates the gas shall be designed to have the gas absorb as much light as possible and to achieve maximum resolution in the analysis, the cross section area and the chamber volume shall be kept as small as possible.
  • the chamber shall be heated to have the substances in gas phase to remain in gas phase and not sublimate.
  • the process is basically a gas chromatography apparatus where a chamber with a light path is added in the end of the column so the separated gas components eluting from the gas chromatograph passes through the chamber and absorbs light with a spectrum that is related to the gas.
  • the remaining lights then passes into a spectrograph and further on to a light sensitive sectioned array preferably a CCD, Charge Coupled Device, so the spatial light components hits individual light sensitive elements enabling spatial detection of the light and thereby allows identification of the substance to be analyzed.
  • a light sensitive sectioned array preferably a CCD, Charge Coupled Device
  • Materials used in such windows can be made of MgF 2 or material with similar optical properties with the drawback like of being sensitive to rapid degradation and consequently loss of transparency and other optical properties if exposed to various chemical substances.
  • Any physical window acts as a filter of passing photons in particular for short wavelength photons. It is also important to keep the spectrograph, its dispersive element and photon sensitive array clean from contamination like particles and residuals from gases, like sublimated matter from gas in order to keep the functionality of the spectrograph.
  • a drawback with prior art is that a physical window has to be cleaned or replaced regularly due to contamination if not being protected by any means. Another issue is measurements with GC-UV, as substances in gas phase enter the light absorbing chamber, is that several substances can protrude the chamber almost with the same velocity and at the same time reducing the ability the physical separation and thereby reducing the ability to chemical identification and quantification.
  • An object of the present invention is to eliminate at least one of the drawbacks mentioned above, which is achieved by assigning to the
  • the invention is very versatile and can be used in various applications such as hand held portable and laboratory based bench top instruments.
  • One particular use is for detection of metabolic or other substances emanating from living cells, tissues and in particular that can be found in exhaled air, saliva, sweat, blood and urine from humans, animals, organisms and plants etc. for detection of various deceases and metabolic activities for example caused by stress.
  • Substances can be such as nitrogen oxide, urea, acetone, isoprene, carbon disulfide coming from diseases like gastric ulcers, asthma, diabetes, psychiatric disorders, drug abuse, stress conditions and intoxications, etc.
  • Many of those metabolic substances in gas phase have significant high absorption of UV light in a spectrum ranging from about 120 nm wave length and longer.
  • the light entrance to the spectrograph is provided with a physical solid barrier like a physical window that has the transparency for UV light from 130 nm wave length with a prevention of gas to be analyzed to come in contact with the window by a flow over the window with gas such as N, He, H or other gases that leaves the window material unaffected.
  • gas such as N, He, H or other gases that leaves the window material unaffected.
  • a similar solution can be used to protect a similar window close to the light source in the light path where UV light enters a light absorbing chamber.
  • a similar solution can be used to protect a similar window close to the light source in the light path where UV light enters a light absorbing chamber.
  • injected flush gas at the light entrance to the light absorption chamber can be used to change, increase the speed of gas to be analyzed through the light absorption chamber and thereby change the separation ability of the substances better from each other and thereby change and also increase the spatial resolution.
  • Such separation can be made nonlinear to the velocity of the gas to be analyzed entering the light absorption chamber and can vary over time by change of pressure and flow of this, the make-up gas.
  • the gas that is used for protecting the windows can simultaneously also be used for diluting and increasing the speed of gas through the light absorbing chamber, in relation to the source of the gas, to shorten the time in the light absorption chamber for the gas to be analyzed and thereby increase spectral - spatial resolution of the readout in the spectrometer.
  • This can be referred to as make up gas.
  • gas used for protecting the window of the light source can simultaneously also be used for flushing through the spectrometer to produce a gas flow of the same make up gas or other with similar properties, in opposite direction to the gas to be analyzed approaching the spectrometer trough the light pipe, to eliminate the flow of gas to be analyzed to enter the spectrometer or reach the window to the spectrometer.
  • the same type of gas can be simultaneously used for all the above functions or different types of gas can be used for the different aspects of the invention.
  • Different pressure at the different locations directs the flow of gas in a desired way from locations with higher pressure to locations with lower pressure. Protection by a gas that flushes the windows preventing the substances to be analyzed in gas phase to reach the surfaces of the windows facing light absorbing chamber in GC-UV applications.
  • Fig. 1 is a schematic view of a first embodiment of an apparatus in accordance with the invention.
  • Fig. 2 is a schematic view of a second embodiment of an apparatus in accordance with the invention.
  • Fig. 1 shows schematically a set up comprising a gas chromatograph (13), a UV-light source (6) connected to a first end of an elongated light absorbing chamber or pipe (3).
  • the UV light source (6) is a deuterium lamp.
  • a spectrometer (1 ) is arranged with an opening without a protective window.
  • the elongated light absorbing chamber (3) shown in Fig. 1 is a light pipe of hollow core type. It can be provided with an Al reflective mirror on the inside or be made of quarts or as a further alternative be made of sapphire.
  • said elongated light absorbing chamber or pipe (3) is enclosed in a heated body (9) capable of providing a temperature of 50 - 280 °C.
  • a gas chromatograph colon (13) is connected with a pipe (8) to said first end of said elongated light absorbing chamber (3) for injecting gas to be analyzed from said gas chromatograph colon (13) in close proximity to the light source (6).
  • a gas distribution control and gas flow regulator (12) provides a flow of gas to said spectrometer (1) preventing gas from said gas chromatograph colon (13) from entering said spectrometer (1 ) since the gas from said spectrometer (1 ) has an opposite direction of flow relative the gas to be analyzed from said gas chromatograph colon (13).
  • a window (5) which can be formed as a lens, is arranged as a protection over said UV-light source (6).
  • the lens (5) can be made of synthetic fused silica alternative sapphire.
  • Said gas distribution control and gas flow regulator (12) also provides a flush gas flow through an inlet (7) at a first end of said elongated light absorbing chamber (3) in order to prevent the gas to be analyzed to reach the window (5) of the UV light source (6).
  • the flow of gas through the inlet (7) can be 0.5 - 10 ml/min.
  • a second optical fiber (2) connects a second end of said elongated light absorbing chamber (3) to the opening of said spectrometer (1 ).
  • said first optical fiber (4) and said second optical fiber (2) are hollow core type fibers typically made of quarts or silica.
  • a light path formed by said first optical fiber (4), said elongated light absorbing chamber (3) and said second optical fiber (2) guides light from said UV-light source (6) to said spectrometer (1 ).
  • a gas flow output (10) is provided at the second end of said elongated light absorbing chamber (3).
  • the embodiment shown in Fig. 2 basically comprises the same components as the embodiment shown in Fig. 1. However, the embodiment shown in Fig. 2 a spectrometer (1) is arranged with an opening covered by a protective window (15). The second optical fiber (2) extends between the second end of said elongated light absorbing chamber (3) and said protective window (15) and is provided with an extension.
  • a gas pipe (14) is connected to said gas distribution control and gas flow regulator (12) to receive a flow of gas that is directed to the extension of said protective window (15). The gas to be analyzed is prevented from reaching the protective window (15) to the spectrometer (1) by a flow of another gas through the pipe (14) has an opposite direction of flow relative the gas to be analyzed.
  • the embodiment of the invention shown in Fig. 2 is directed to a method and an apparatus of increasing the long term transparency of light windows of very and increase spatial resolution of read out of short wavelengths, such as 130nm and up, photons in GC-UV applications.
  • a spectrograph (1 ) is arranged with a slit where light enters and a dispersive element that reflects the fractioned light.
  • a spectrometer is a spectrograph that has a photon collecting device to collect the fractioned light for read out and measurement of spectra.
  • the Photon collecting device can be a CCD - Charge Collecting Device.

Abstract

A method and an apparatus for obtaining photonic signal levels and spatial resolution from samples in gas phase of substances in a first flow of gas by a first step comprising selection by time by gas chromatography and by a second step comprising absorption of photons by UV light down to 120 nm of wavelength that passes a light absorbing chamber for identification and quantification of substances. A second flow of an additional gas different from said gas phase samples is directed over light source windows inside the light absorbing chamber, so as to protect said light source windows and to prevent said light source windows from being in contact with the gas phase samples to be analyzed. The apparatus comprises a gas chromatograph (13) and a UV light source (6) connected to an elongated light absorbing chamber (3) for identification and quantification of substances. It further comprises a window (5) over said UV light source (6) and a gas flow regulator (12) directing a second flow of an additional gas different from said gas phase samples through an inlet (7) over said window (5).

Description

MAKE UP AND PROTECTIVE GAS FOR LIGHT PATH WINDOW MATERIALS AND INCREASED SPATIAL RESOLUTION IN GAS CHROMATOGRAPHY - UV DETECTION.
TECHNICAL FIELD
[0001] The present invention relates Gas Chromatography, GC - Ultraviolet absorption, UV - spectroscopy, GC-UV, to detect, identify and analyse gases, liquids and solid known and unknown substances from high to very low
concentrations and is directed to a method and an apparatus for obtaining photonic signal levels and spatial resolution from samples in gas phase of substances in a first flow of gas by a first step comprising selection by time by gas chromatography and by a second step comprising absorption of photons by UV light down to 120 nm of wavelength that passes a light absorbing chamber for identification and quantification of substances.
BACKGROUND ART
[0002] The basic technology is known and used for various purposes. Such solutions are disclosed in US6305213 and US4668091 , Verner Lagesson et. al. The invention relates to physical, mechanical and software control solutions. The invention solves one of the major problems to achieve in order to detect absorption of very short wavelengths (typically down to 120nm) for identification of unknown substances in gas phase.
[0003] Gas chromatography UV - spectroscopy is used for identification and quantification of various substances that can be transformed into gas. The technology is based on that substances in gas phase first passes through a heated column where the gas has a substance dependent velocity through the column and when the gas to be analyzed leaves the first heated column and enters a chamber where UV light passes the gas, absorb light when the light passes the gas, in a spectral way, so the photonic spectrum relates with very high accuracy to the identity of the substance. [0004] The light used for the absorption shall preferably have a broad spectrum of wavelengths to allow absorption over a broad spectrum of wavelengths. The passage, chamber, where light penetrates the gas shall be designed to have the gas absorb as much light as possible and to achieve maximum resolution in the analysis, the cross section area and the chamber volume shall be kept as small as possible. The chamber shall be heated to have the substances in gas phase to remain in gas phase and not sublimate.
[0005] The process is basically a gas chromatography apparatus where a chamber with a light path is added in the end of the column so the separated gas components eluting from the gas chromatograph passes through the chamber and absorbs light with a spectrum that is related to the gas.
[0006] The remaining lights then passes into a spectrograph and further on to a light sensitive sectioned array preferably a CCD, Charge Coupled Device, so the spatial light components hits individual light sensitive elements enabling spatial detection of the light and thereby allows identification of the substance to be analyzed.
[0007] Light is directed in to the spectrograph trough a passage that can be a window made out of a photon transparent material that allow passage of the required wavelengths. In order to have maximum number of photons to reach the light sensitive element it is important to use windows separating the spectrograph from the gas path in material that has very high transparency, particular in the low wavelength range.
[0008] Materials used in such windows can be made of MgF2 or material with similar optical properties with the drawback like of being sensitive to rapid degradation and consequently loss of transparency and other optical properties if exposed to various chemical substances. Any physical window acts as a filter of passing photons in particular for short wavelength photons. It is also important to keep the spectrograph, its dispersive element and photon sensitive array clean from contamination like particles and residuals from gases, like sublimated matter from gas in order to keep the functionality of the spectrograph. [0009] A drawback with prior art is that a physical window has to be cleaned or replaced regularly due to contamination if not being protected by any means. Another issue is measurements with GC-UV, as substances in gas phase enter the light absorbing chamber, is that several substances can protrude the chamber almost with the same velocity and at the same time reducing the ability the physical separation and thereby reducing the ability to chemical identification and quantification.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to eliminate at least one of the drawbacks mentioned above, which is achieved by assigning to the
characteristics according to descriptions and claims.
[0011] The invention is very versatile and can be used in various applications such as hand held portable and laboratory based bench top instruments. One particular use is for detection of metabolic or other substances emanating from living cells, tissues and in particular that can be found in exhaled air, saliva, sweat, blood and urine from humans, animals, organisms and plants etc. for detection of various deceases and metabolic activities for example caused by stress. Substances can be such as nitrogen oxide, urea, acetone, isoprene, carbon disulfide coming from diseases like gastric ulcers, asthma, diabetes, psychiatric disorders, drug abuse, stress conditions and intoxications, etc. Many of those metabolic substances in gas phase have significant high absorption of UV light in a spectrum ranging from about 120 nm wave length and longer.
[0012] According to a first aspect of the invention, the light entrance to the spectrograph is provided with a physical solid barrier like a physical window that has the transparency for UV light from 130 nm wave length with a prevention of gas to be analyzed to come in contact with the window by a flow over the window with gas such as N, He, H or other gases that leaves the window material unaffected.
[0013] A similar solution can be used to protect a similar window close to the light source in the light path where UV light enters a light absorbing chamber. A similar solution can be used to protect a similar window close to the light source in the light path where UV light enters a light absorbing chamber.
[0014] According to a second aspect of the invention, injected flush gas, to be referred to as make up gas, at the light entrance to the light absorption chamber can be used to change, increase the speed of gas to be analyzed through the light absorption chamber and thereby change the separation ability of the substances better from each other and thereby change and also increase the spatial resolution. Such separation can be made nonlinear to the velocity of the gas to be analyzed entering the light absorption chamber and can vary over time by change of pressure and flow of this, the make-up gas.
[0015] According to a third aspect of the invention, the gas that is used for protecting the windows can simultaneously also be used for diluting and increasing the speed of gas through the light absorbing chamber, in relation to the source of the gas, to shorten the time in the light absorption chamber for the gas to be analyzed and thereby increase spectral - spatial resolution of the readout in the spectrometer. This can be referred to as make up gas.
[0016] According to a fourth aspect of the invention, is that gas used for protecting the window of the light source can simultaneously also be used for flushing through the spectrometer to produce a gas flow of the same make up gas or other with similar properties, in opposite direction to the gas to be analyzed approaching the spectrometer trough the light pipe, to eliminate the flow of gas to be analyzed to enter the spectrometer or reach the window to the spectrometer.
[0017] The same type of gas can be simultaneously used for all the above functions or different types of gas can be used for the different aspects of the invention. Different pressure at the different locations directs the flow of gas in a desired way from locations with higher pressure to locations with lower pressure. Protection by a gas that flushes the windows preventing the substances to be analyzed in gas phase to reach the surfaces of the windows facing light absorbing chamber in GC-UV applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order that the manner in which the above recited and other
advantages and objects of the invention are obtained will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. The same reference numerals have been used to indicate the same parts in the figures to increase the readability of the description and for the sake of clarity. The figures are not made to scale, and the relative dimensions of the illustrated objects may be disproportional.
[0019] Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Fig. 1 is a schematic view of a first embodiment of an apparatus in accordance with the invention, and
Fig. 2 is a schematic view of a second embodiment of an apparatus in accordance with the invention.
[0020] Fig. 1 shows schematically a set up comprising a gas chromatograph (13), a UV-light source (6) connected to a first end of an elongated light absorbing chamber or pipe (3). In various embodiments the UV light source (6) is a deuterium lamp. In the embodiment shown in Fig. 1 a spectrometer (1 ) is arranged with an opening without a protective window. The elongated light absorbing chamber (3) shown in Fig. 1 is a light pipe of hollow core type. It can be provided with an Al reflective mirror on the inside or be made of quarts or as a further alternative be made of sapphire. In various embodiments said elongated light absorbing chamber or pipe (3) is enclosed in a heated body (9) capable of providing a temperature of 50 - 280 °C.
[0021] A gas chromatograph colon (13) is connected with a pipe (8) to said first end of said elongated light absorbing chamber (3) for injecting gas to be analyzed from said gas chromatograph colon (13) in close proximity to the light source (6). A gas distribution control and gas flow regulator (12) provides a flow of gas to said spectrometer (1) preventing gas from said gas chromatograph colon (13) from entering said spectrometer (1 ) since the gas from said spectrometer (1 ) has an opposite direction of flow relative the gas to be analyzed from said gas chromatograph colon (13).
[0022] Light from said UV-light source (6) is guided through a first optical fiber (4) to said first end of said elongated light absorbing chamber (3). A window (5), which can be formed as a lens, is arranged as a protection over said UV-light source (6). The lens (5) can be made of synthetic fused silica alternative sapphire. Said gas distribution control and gas flow regulator (12) also provides a flush gas flow through an inlet (7) at a first end of said elongated light absorbing chamber (3) in order to prevent the gas to be analyzed to reach the window (5) of the UV light source (6). The flow of gas through the inlet (7) can be 0.5 - 10 ml/min.
[0023] A second optical fiber (2) connects a second end of said elongated light absorbing chamber (3) to the opening of said spectrometer (1 ). In various embodiments said first optical fiber (4) and said second optical fiber (2) are hollow core type fibers typically made of quarts or silica. A light path formed by said first optical fiber (4), said elongated light absorbing chamber (3) and said second optical fiber (2) guides light from said UV-light source (6) to said spectrometer (1 ). A gas flow output (10) is provided at the second end of said elongated light absorbing chamber (3).
[0024] As long as the pressure is higher at the point where the gas enters the spectrometer than the point where it leaves the spectrometer there will be a gas flow where the gas has a velocity preventing gas or particles to enter the spectrograph.
[0025] The embodiment shown in Fig. 2 basically comprises the same components as the embodiment shown in Fig. 1. However, the embodiment shown in Fig. 2 a spectrometer (1) is arranged with an opening covered by a protective window (15). The second optical fiber (2) extends between the second end of said elongated light absorbing chamber (3) and said protective window (15) and is provided with an extension. A gas pipe (14) is connected to said gas distribution control and gas flow regulator (12) to receive a flow of gas that is directed to the extension of said protective window (15). The gas to be analyzed is prevented from reaching the protective window (15) to the spectrometer (1) by a flow of another gas through the pipe (14) has an opposite direction of flow relative the gas to be analyzed.
[0026] The embodiment of the invention shown in Fig. 2 is directed to a method and an apparatus of increasing the long term transparency of light windows of very and increase spatial resolution of read out of short wavelengths, such as 130nm and up, photons in GC-UV applications.
[0027] While certain illustrative embodiments of the invention have been described in particularity, it will be understood that various other modifications will be readily apparent to those skilled in the art without departing from the scope and spirit of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description set forth herein but rather that the claims be construed as encompassing all equivalents of the present invention which are apparent to those skilled in the art to which the invention pertains.
[0028] Additionally, although individual features may be included in different embodiments, these may possibly be combined in other ways, and the inclusion in different embodiments does not imply that a combination of features is not feasible. In addition, singular references do not exclude a plurality. The terms "a", "an" does not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.
[0029] Definitions used above are: A spectrograph (1 ) is arranged with a slit where light enters and a dispersive element that reflects the fractioned light. A spectrometer is a spectrograph that has a photon collecting device to collect the fractioned light for read out and measurement of spectra. The Photon collecting device can be a CCD - Charge Collecting Device.

Claims

1. A method for obtaining photonic signal levels and spatial resolution from samples in gas phase of substances in a first flow of gas by a first step
comprising selection by time by gas chromatography and by a second step comprising absorption of photons by UV light down to 120 nm of wavelength that passes a light absorbing chamber for identification and quantification of substances, characterized by directing a second flow of an additional gas different from said gas phase samples over light source windows inside the light absorbing chamber, so as to protect said light source windows and to prevent said light source windows from being in contact with the gas phase samples to be analyzed.
2. A method for obtaining photonic signal levels and spatial resolution from samples in gas phase of substances in a first flow of gas by a first step comprising selection by time by gas chromatography and by a second step comprising absorption of photons by UV light down to 120 nm of wavelength that passes a light absorbing chamber (3) for identification and quantification of substances, characterized by diluting the gas to be analyzed in close proximity to a light entrance to said light absorbing chamber (3) by directing a second flow of an additional gas different from said gas phase samples through an inlet (7) between a window (5) of a light source (6) and a pipe (8) through which said first flow of gas is injected into said light absorbing chamber, so as to increase the velocity of gas through the light absorbing chamber (3) and thereby to increase spatial UV resolution of a following spectrometer (1 ) receiving light passing through said light absorbing chamber (3).
3. A method as claimed in claim 1 or 2, including directing said second flow of an additional gas different from said gas phase samples at a pressure higher than the pressure of the gas in the first flow of gas.
4. A method as claimed in any of claims 1 -3, wherein the additional other gas is H2, He, N2 or other low molecular weight, inert gas.
5. An apparatus for obtaining photonic signal levels and spatial resolution from samples in gas phase of substances in a first flow of gas, comprising a gas chromatograph (13) and a UV light source (6) connected to an elongated light absorbing chamber (3) for identification and quantification of substances, characterized by a window (5) over said UV light source (6), a gas flow regulator (12) directing a second flow of an additional gas different from said gas phase samples through an inlet (7) over said window (5) to prevent said window (5) from being in contact with said first flow of gas, a pipe (8) connecting said gas chromatograph (13) to a first end of said elongated light absorbing chamber (3), a first optical fiber (4) directing light from said UV light source (6) to said first end of said elongated light absorbing chamber (3), a second optical fiber (2) connecting a second end of said light absorbing chamber (3) to a spectrometer (1 ) and a gas flow output (10) provided at said second end of said elongated light absorbing chamber (3), said first optical fiber (4), said elongated light absorbing chamber (3) and said second optical fiber (2) together forming a light path between said UV light source (6) and said spectrometer.
6. An apparatus as claimed in claim 5, wherein said first optical fiber (4) and said second optical fiber (2) are hollow core type fibers.
7. An apparatus as claimed in claim 5, wherein a window (15) is provided in the light path at an opening to said spectrometer (1 ) and wherein a gas pipe (14) is connected to said second optical fiber (2) to direct a flow of a protective gas over said window (15).
8. An apparatus as claimed in claim 5, wherein said elongated light absorbing chamber (3) is embedded in a heated body (9) with a temperature range between 50 and 280 °C.
9. An apparatus as claimed in claim 7, wherein said gas flow regulator (12) is connected for supplying the same type of gas to said gas pipe (14) and to said inlet (7).
PCT/SE2012/050245 2011-03-05 2012-03-05 Make up and protective gas for light path window materials and increased spatial resolution in gas chromatography - uv detection WO2012121651A1 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014062419A1 (en) 2012-10-18 2014-04-24 Vuv Analytics, Inc. Vacuum ultraviolet absorption spectroscopy system and method
WO2014128180A1 (en) 2013-02-20 2014-08-28 Chromalytica Ab Uv light emitting diode as light source in gas chromatography-uv absorption spectrophotometry
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