WO2007000592A1 - A method of spectral analysis and an apparatus for performing the method - Google Patents

A method of spectral analysis and an apparatus for performing the method Download PDF

Info

Publication number
WO2007000592A1
WO2007000592A1 PCT/GB2006/002368 GB2006002368W WO2007000592A1 WO 2007000592 A1 WO2007000592 A1 WO 2007000592A1 GB 2006002368 W GB2006002368 W GB 2006002368W WO 2007000592 A1 WO2007000592 A1 WO 2007000592A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
sample
integrating sphere
sphere
sample container
Prior art date
Application number
PCT/GB2006/002368
Other languages
French (fr)
Inventor
William Nevil Heaton Johnson
Christopher Glynn
Original Assignee
H-Icheck Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by H-Icheck Limited filed Critical H-Icheck Limited
Priority to EP06755652A priority Critical patent/EP1949080A1/en
Publication of WO2007000592A1 publication Critical patent/WO2007000592A1/en

Links

Classifications

    • 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
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/359—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using near infrared light
    • 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
    • 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
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N2021/317—Special constructive features
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/065—Integrating spheres

Definitions

  • THE PRESENT INVENTION relates to a method of spectral analysis and more particularly relates to a method of spectral analysis of a liquid sample.
  • the invention also relates to an apparatus for performing the method.
  • the present invention seeks to provide a new method of performing spectral analysis of a liquid sample and an apparatus for performing the method.
  • a method of determining the concentration of at least one component in a liquid sample comprising the steps of directing light from a light source into an integrating sphere, mounting a sample holder containing the liquid sample to or adjacent the integrating sphere, to expose the sample to the light, withdrawing light from the sphere, performing a spectral analysis on the light to provide data relating to the intensity of light at least at certain predetermined wavelengths, processing the data from the spectral analysis to determine the presence of and concentration of said at least one component and displaying or printing information generated during the processing step.
  • the light has a predetermined spectral range.
  • the light has a substantial component in the near-infrared range.
  • the light source is pulsed to give successive pulses of light.
  • the step of withdrawing light from the sphere may be effected after the end of a pulse of light.
  • the light directed into the integrating sphere may be polarised. This may facilitate the analysis of certain materials.
  • the liquid is transparent to at least part of the frequency spectrum of the light and the sample holder is mounted between the light source and the integrating sphere so the light passes through the sample before entering the sphere.
  • the sample holder is mounted to the integrating sphere to expose the sample to light within the sphere.
  • the light directed into the integrating sphere is focused on to the sample.
  • the method comprises the step of adjusting the optical characteristic of the sample holder by altering the reflectance/absorbence/transmittance of part of the sample holder remote from the interior of the integrating sphere.
  • the liquid is opaque to at least part of the frequency spectrum of the light.
  • the liquid is blood.
  • the component is selected from the group comprising alcohol, glucose, haemoglobin, sodium, potassium.
  • an apparatus for performing spectral analysis of a liquid sample comprising an integrating sphere, the integrating sphere having a light inlet and a light outlet, the integrating sphere having an aperture to receive a sample container, there being a sample container engageable with the aperture, the sample container having a convex wall, the convex wall having a radius of curvature substantially equal to that of the interior of the integrating sphere, the arrangement being such that when the sample container is mounted to the integrated sphere the convex wall of the sample container is substantially aligned with the interior of the sphere.
  • the aperture to receive the sample container is the light inlet.
  • the aperture to receive the sample container is spaced from the light inlet.
  • part of the sample container remote from the convex wall is provided with a light reflective property.
  • part of the sample container remote from the convex wall is provided with a light absorbent property.
  • part of the sample container remote from the convex wall is provided with a light transmissive property.
  • an apparatus for performing spectral analysis of a liquid sample comprising an integrating sphere, the integrating sphere having a light inlet and a light outlet and having an aperture spaced from the light inlet to receive a sample container to expose a sample in the sample container to light in the integrating sphere, a part of the sample container having a light reflective on a light absorbent property.
  • the sample container is associated with a removable element, the element providing the light reflective or a light absorbence property.
  • the removable element is a spectral filter.
  • FIGURE 1 is a partially diagrammatic and partially exploded view of one apparatus for performing the method of the invention
  • FIGURES 2 to 5 are diagrammatic figures provided for the purposes of explanation,
  • FIGURE 6 is a corresponding exploded view of a second embodiment of the invention.
  • FIGURE 7 is an enlarged section of exploded view of components of the apparatus of Figure 2.
  • an apparatus for performing a spectral analysis of a liquid, in order to determine the concentration of specific chemicals or other components present in the liquid.
  • the chemicals or the components in the liquid may be normally present in the liquid (such as glucose in blood) or may be present on certain occasions (such as alcohol or drugs in blood).
  • the liquid may be an opaque liquid, such as blood.
  • An opaque liquid is a liquid which will not let visible light pass through it, or which will not let light in a significant part of the spectrum (including infrared and ultra violet) pass through it.
  • the apparatus illustrated in Figure 1 comprises a light source 1.
  • the light source 1 may be any convenient light source providing constant uniform intensity light within the visible spectrum, the near-infrared and/or the near ultraviolet.
  • the word "light” as used in this Specification is intended to include infrared and ultraviolet light.
  • the light source 1 may be provided with a filter 2, the filter 2 serving to limit the spectral range of the light from the light source 1.
  • the light passing through the filter may only be in the near-infrared part of the spectrum, or in the near-infrared and the "red" end of the visible spectrum.
  • the light from the light source 1 is directed into an integrating sphere 3.
  • the integrating sphere 3 is provided with a spherical body 4 formed from two hemispherical parts interconnected by means of a flange 5.
  • the interior surface of the sphere is reflective to the light which is introduced to the integrating sphere.
  • the interior of the sphere may be coated with a stable barium sulphate based white coating, or the sphere may be formed from a thermoplastic material which may be reflective to light of a wide range of wavelengths, including very low wavelengths.
  • a first aperture 6 is provided in the sphere, the aperture 6 being configured to accommodate a mounting flange 8 which is used, for example, to mount a fibre optic bundle 9 which extends from the light source, so that light is directed through the aperture 6 into the interior of the integrating sphere 3.
  • the aperture 6 may also be provided with a focusing arrangement.
  • a second aperture 10 is formed on the sphere.
  • the aperture 10 is located directly opposite to the first aperture 6, but the aperture 10 could have any convenient location within the sphere which is spaced from the first aperture 6.
  • the aperture 10 is configured to receive a sample bottle holder 11.
  • the sample bottle holder 11 comprises a base 12, carrying two upstanding walls 13,14.
  • the upstanding wall 13 is provided with an aperture 15 which engages with the aperture 10 formed in the integrating sphere.
  • a space is defined between the two upstanding walls 13,14 dimensioned to receive a sample bottle or cuvette 16.
  • the sample bottle may contain a liquid.
  • the sample bottle is, of course, formed of a material which is transparent to light having wavelengths within the spectral band being supplied by the light source to the interior of the integrating sphere.
  • the sample bottle 16 may be held at a position where light from the light source is focussed, so that the sample is exposed to a precisely predetermined amount of light.
  • the aperture 17 being associated, in this case, with an aperture reducer 18 on which is mounted an accessory adapter 19, the accessory adapter 19 supporting a light trap 20.
  • the light trap 20 is connected to a spectroscope 21 configured to conduct a spectral analysis of light received in the light trap, to determine the intensity of the light received at each wavelength.
  • the spectroscope may be a "selective" spectroscope and may only determine the intensity of light at specific predetermined wavelengths.
  • the output of the spectroscope is passed to a processor 22, configured to perform an analysis of the data provided by the spectroscope, and the processor is associated with a display/printer 23 configured to display or print results determined by the processor.
  • the interior of the integrating sphere maybe provided with one or more baffles to present light passing directly from the first aperture 6 to the light trap and/or to prevent light passing directly from the sample bottle 16 to the light trap.
  • the apparatus illustrated in Figure 1 may be utilised to perform an analysis of a liquid sample within the sample bottle or cuvette 16, even if the sample is a liquid which is opaque, such as blood.
  • the blood is placed in the sample bottle or cuvette 16, the sample bottle or cuvette 16 is mounted in the holder 11 , and the holder 11 is mounted to the aperture 10 in the integrating sphere.
  • the sample within the bottle is thus exposed to the interior of the sphere, and will thus be exposed to the light that is directed into the sphere.
  • Light from the light source 1 , passing through the filter 2 and the fibre optic bundle 9 is directed into the integrating sphere.
  • the light may be focussed on to the blood sample within the sample bottle, and that light is effectively "reflected" into the interior of the sphere. Some wavelengths of light are reflected almost totally, but other wavelengths of light are partially, or sometimes completely, absorbed by the blood. The light that is reflected from the sample is consequently not of the same spectral content as the light entering the sphere.
  • the integrating sphere is, of itself, a known component. Light within an integrating sphere is uniformly reflected and scattered around the interior of the sphere, with the light sometimes effecting many multiple reflections and re-reflections.
  • the interior of the sphere whilst being “reflective” of light is not a “mirror” finish, but instead reflects light in a “diffuse” manner. The whole of the interior of the sphere is thus exposed to a substantially uniform illumination, and at any point on the surface of the sphere light will be present which has a spectral content which is determined by the light absorption/reflection characteristics of the sample in the sample bottle or cuvette 16.
  • Light having the specific spectral content will thus emerge from the integrating sphere through the aperture 17 and will pass into the light trap 20.
  • the light passes to the spectroscope 21 , which performs a spectral analysis to provide data related to the intensity of light at a plurality of wavelengths.
  • wavelengths are selected so that there will be no "interference" from other constituents of the liquid, such as water.
  • the wavelengths selected are wavelengths where a "peak” is expected to be if, and only if, a specific component or chemical is present.
  • each of the wavelengths to be analysed is represented as a separate "dimension" in a notional poly-dimensional space.
  • the relative intensity of light of each selected wavelength is measured, as shown in Figure 2.
  • the three intensities of light and three wavelengths may be shown on three separate lines, as shown in Figure 3.
  • the three separate lines may form three orthogonal axis, as shown in Figure 4, and consequently, a single point, identified as the point O in Figure 5 can be defined, from the three measurements which have been taken. It is to be appreciated that if subsequent measurements of the further sample lead to a point line on the line 24 shown in Figure 5 which passes from the origin of the orthogonal space, and which passes through the point O than the present of a point on that line indicates the presence of the same substance that was in the sample initially tested, and the position on the line 24 indicates the concentration of the sample.
  • a further technique that may be utilised involves Fourier analysis of the sometimes complex initial output of the spectroscope, the Fourier analysis being intended to identify underlying "wave forms" which make up the complex "wave form” of the spectroscope output.
  • the Fourier analysis may identify several underlying "wave forms", each with a different amplitude. Each of those "wave forms” may be representative of a particular component of the sample and the amplitude of the wave form is representative of the concentration of that component within the sample.
  • the processor 20 may utilise many different techniques to process the data from the spectral analysis, and the processor will operate to determine the presence of, and also the concentration of, at least one predetermined component within the sample.
  • the processor may be programmed to determine the concentration of alcohol in the blood or the concentration of glucose in the blood or the concentration of any other blood component that is of interest.
  • the processor may therefore perform the necessary processing steps to produce an output which is indicative of the presence of and the concentration of a large number of potential components in the sample.
  • the processor provides an output to a display device or printer 23 which gives a visible indication of the results produced by the processor.
  • a "screen” or printout may be provided which indicates the presence of one or more components in the blood, giving the concentration of each component.
  • the components may be alcohol, glucose, haemoglobin, sodium, potassium or other components that may be of interest.
  • a sample of a liquid which may be opaque, such as blood
  • the sample bottle or cuvette 16 may be mounted to the integrating sphere 3, and subsequently the spectroscope will analyse light emerging from the integrating sphere with the output of the spectroscope being processed by a processor to determine the light absorption/reflection characteristics to be determined and processed to enable a display to display information (or a printer to print information), that information including an indication of the presence of and the concentration of specific components in the blood.
  • the entire process may be complete within a few moments, and with great repeatability and high accuracy.
  • the method Whilst the method has been described, with reference to Figure 1 , in the context of opaque liquid, the method may be formed using a substantially
  • transparent liquid such as a clear aqueous solution. If a liquid of this type is to be used the side of the cuvette or sample bottle 16 which is furthest from the aperture 10, or the inner face of the upstanding wall 14 of the sample holder may be provided with a "reflective" coating equivalent to the reflective coating provided on the interior of the integrating sphere, or in the form of a mirror-like coating.
  • the aperture 10 in the sphere is replaced by a relatively large aperture 30.
  • the sample bottle 16 is replaced by a sample container 31.
  • the sample container 31 is provided with a discshaped upper part 32 which carries a central axially extending chamber 33, that chamber terminating with a concave wall 34, the concave wall 34 having a radius of curvature substantially equal to the radius of curvature of the integrating sphere.
  • the sample container 31 is mounted to the aperture 30 by means of a mounting collar 35, the mounting collar 35 having an internally threaded ring 36 to engage threading provided on the exterior of the aperture 30 and an inwardly directed flange 37, the flange being configured to overlie the disc-shaped part 32 of the sample container 31.
  • the concave face 34 of the sample container 31 is substantially aligned with interior of the sphere, so that the interior of the sphere and the concave face 34 of the sample container 31 is a smooth, virtually unbroken, uniformly curved part of a spherical surface, thus facilitating the even and uniform reflection and diffusion of light within the integrating sphere.
  • the uppermost wall of the disc-shaped part of the sample container, the wall 35 may be provided with a reflective coating which may be equivalent to the reflective coating provided within the integrating sphere, or which may be a mirror-like reflective coating.
  • a light absorbing coating may be provided to give a light absorbing property, so that any light passing through the sample is totally absorbed.
  • the said coatings may be present on separate elements, such as plates, configured to be brought into engagement with the appropriate parts of the sample bottle.
  • the plates may both be put to one side, to provide the sample bottle with a light transmissive property, enabling light which has passed through the sample to emerge from the integrating sphere. This light may be spectrally analysed.
  • the sample holder may be associated with a removable element in the form of a spectral filter.
  • the spectral filter will allow light of selected wavelengths to be transmitted through the filter and/or reflected back into the sample holder.
  • sample may be provided at an aperture which is spaced from the light inlet.
  • the sample may be provided at the light inlet, thus being positioned between the light source and the integrating sphere so that the light passes through the sample before entering the light integrating sphere. If the sample is provided at the light inlet it may need to be in a sample holder with parallel straight walls to avoid unwanted reflections from, for example, a concave wall.
  • the light source is a source which provides a constant uniform intensity light.
  • the source may be a pulsed source.
  • the spectroscopic analysis may be performed shortly after the end of each input pulse of light. Successive input pulses may have different spectral contents. Some pulses may be substantially monochromatic, but other pulses may contain specific selected wavelengths of light.
  • the light may be polarised, being either plane polarised or circular polarised.

Abstract

The concentration of a component such as alcohol or glucose in a sample of an opaque liquid such as blood is determined by mounting a sample holder (16) containing the liquid sample (2) or adjacent an integrating sphere (3) and directing light from a light source (1) into the integrated sphere (3 )so that the sample is exposed to the light and light from the sample passes into the integrated sphere. A spectral analysis is performed on light from the integrating sphere and the results processed and displayed or printed as information as to the presence and/or concentration of the component in the sample.

Description

A METHOD OF SPECTRAL ANALYSIS AND AN APPARATUS FOR PERFORMING THE METHOD
Description of Invention
THE PRESENT INVENTION relates to a method of spectral analysis and more particularly relates to a method of spectral analysis of a liquid sample. The invention also relates to an apparatus for performing the method.
It is desirable to be able to perform a spectral analysis of a liquid sample using light, and preferably using light in the near-infrared part of the spectrum.
The present invention seeks to provide a new method of performing spectral analysis of a liquid sample and an apparatus for performing the method.
According to one aspect of this invention there is provided a method of determining the concentration of at least one component in a liquid sample, the method comprising the steps of directing light from a light source into an integrating sphere, mounting a sample holder containing the liquid sample to or adjacent the integrating sphere, to expose the sample to the light, withdrawing light from the sphere, performing a spectral analysis on the light to provide data relating to the intensity of light at least at certain predetermined wavelengths, processing the data from the spectral analysis to determine the presence of and concentration of said at least one component and displaying or printing information generated during the processing step.
Preferably the light has a predetermined spectral range. Conveniently the light has a substantial component in the near-infrared range.
In one embodiment the light source is pulsed to give successive pulses of light.
In this embodiment the step of withdrawing light from the sphere may be effected after the end of a pulse of light.
Conveniently successive pulses of light have different spectral content.
It is envisaged that the light directed into the integrating sphere may be polarised. This may facilitate the analysis of certain materials.
In one method the liquid is transparent to at least part of the frequency spectrum of the light and the sample holder is mounted between the light source and the integrating sphere so the light passes through the sample before entering the sphere.
In another method the sample holder is mounted to the integrating sphere to expose the sample to light within the sphere.
Conveniently the light directed into the integrating sphere is focused on to the sample.
Conveniently the method comprises the step of adjusting the optical characteristic of the sample holder by altering the reflectance/absorbence/transmittance of part of the sample holder remote from the interior of the integrating sphere. In another method the liquid is opaque to at least part of the frequency spectrum of the light..
Preferably the liquid is blood.
Conveniently the component is selected from the group comprising alcohol, glucose, haemoglobin, sodium, potassium.
According to a further aspect of this invention there is provided an apparatus for performing spectral analysis of a liquid sample, the apparatus comprising an integrating sphere, the integrating sphere having a light inlet and a light outlet, the integrating sphere having an aperture to receive a sample container, there being a sample container engageable with the aperture, the sample container having a convex wall, the convex wall having a radius of curvature substantially equal to that of the interior of the integrating sphere, the arrangement being such that when the sample container is mounted to the integrated sphere the convex wall of the sample container is substantially aligned with the interior of the sphere.
In one embodiment the aperture to receive the sample container is the light inlet.
Alternatively the aperture to receive the sample container is spaced from the light inlet.
Conveniently part of the sample container remote from the convex wall is provided with a light reflective property.
Alternatively part of the sample container remote from the convex wall is provided with a light absorbent property. Alternatively again part of the sample container remote from the convex wall is provided with a light transmissive property.
According to another aspect of the invention there is provided an apparatus for performing spectral analysis of a liquid sample, the apparatus comprising an integrating sphere, the integrating sphere having a light inlet and a light outlet and having an aperture spaced from the light inlet to receive a sample container to expose a sample in the sample container to light in the integrating sphere, a part of the sample container having a light reflective on a light absorbent property.
Preferably the sample container is associated with a removable element, the element providing the light reflective or a light absorbence property. In one embodiment the removable element is a spectral filter.
In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIGURE 1 is a partially diagrammatic and partially exploded view of one apparatus for performing the method of the invention,
FIGURES 2 to 5 are diagrammatic figures provided for the purposes of explanation,
FIGURE 6 is a corresponding exploded view of a second embodiment of the invention, and
FIGURE 7 is an enlarged section of exploded view of components of the apparatus of Figure 2. Turning initially to Figure 1 an apparatus is provided for performing a spectral analysis of a liquid, in order to determine the concentration of specific chemicals or other components present in the liquid. The chemicals or the components in the liquid may be normally present in the liquid (such as glucose in blood) or may be present on certain occasions (such as alcohol or drugs in blood). As will become clear, the liquid may be an opaque liquid, such as blood. An opaque liquid is a liquid which will not let visible light pass through it, or which will not let light in a significant part of the spectrum (including infrared and ultra violet) pass through it.
The apparatus illustrated in Figure 1 comprises a light source 1. The light source 1 may be any convenient light source providing constant uniform intensity light within the visible spectrum, the near-infrared and/or the near ultraviolet. Of course, the word "light" as used in this Specification is intended to include infrared and ultraviolet light. The light source 1 may be provided with a filter 2, the filter 2 serving to limit the spectral range of the light from the light source 1. Thus, for example, the light passing through the filter may only be in the near-infrared part of the spectrum, or in the near-infrared and the "red" end of the visible spectrum.
The light from the light source 1 is directed into an integrating sphere 3.
The integrating sphere 3 is provided with a spherical body 4 formed from two hemispherical parts interconnected by means of a flange 5. The interior surface of the sphere is reflective to the light which is introduced to the integrating sphere. For example, the interior of the sphere may be coated with a stable barium sulphate based white coating, or the sphere may be formed from a thermoplastic material which may be reflective to light of a wide range of wavelengths, including very low wavelengths. A first aperture 6 is provided in the sphere, the aperture 6 being configured to accommodate a mounting flange 8 which is used, for example, to mount a fibre optic bundle 9 which extends from the light source, so that light is directed through the aperture 6 into the interior of the integrating sphere 3. The aperture 6 may also be provided with a focusing arrangement.
A second aperture 10 is formed on the sphere. In the embodiment illustrated the aperture 10 is located directly opposite to the first aperture 6, but the aperture 10 could have any convenient location within the sphere which is spaced from the first aperture 6. The aperture 10 is configured to receive a sample bottle holder 11.
The sample bottle holder 11 comprises a base 12, carrying two upstanding walls 13,14. The upstanding wall 13 is provided with an aperture 15 which engages with the aperture 10 formed in the integrating sphere. A space is defined between the two upstanding walls 13,14 dimensioned to receive a sample bottle or cuvette 16. The sample bottle may contain a liquid. The sample bottle is, of course, formed of a material which is transparent to light having wavelengths within the spectral band being supplied by the light source to the interior of the integrating sphere. The sample bottle 16 may be held at a position where light from the light source is focussed, so that the sample is exposed to a precisely predetermined amount of light.
At a further position on the integrating sphere there is a further aperture 17, the aperture 17 being associated, in this case, with an aperture reducer 18 on which is mounted an accessory adapter 19, the accessory adapter 19 supporting a light trap 20.
The light trap 20 is connected to a spectroscope 21 configured to conduct a spectral analysis of light received in the light trap, to determine the intensity of the light received at each wavelength. Of course, the spectroscope may be a "selective" spectroscope and may only determine the intensity of light at specific predetermined wavelengths.
The output of the spectroscope is passed to a processor 22, configured to perform an analysis of the data provided by the spectroscope, and the processor is associated with a display/printer 23 configured to display or print results determined by the processor.
The interior of the integrating sphere maybe provided with one or more baffles to present light passing directly from the first aperture 6 to the light trap and/or to prevent light passing directly from the sample bottle 16 to the light trap.
The apparatus illustrated in Figure 1 may be utilised to perform an analysis of a liquid sample within the sample bottle or cuvette 16, even if the sample is a liquid which is opaque, such as blood.
Here it is to be appreciated that it is difficult to perform a spectroscopic analysis of blood since blood is opaque to light, and consequently it is not possible to perform an absorption spectrographic analysis of blood, since all of the incident light would be absorbed and it would not be possible to identify any "peaks" in light transmitted through a sample of blood. However, it has been found that, by using the integrated sphere, a sample of blood can be analysed by performing spectral analysis on light "reflected" from the blood, and it is possible to determine the concentration of certain components in the blood such as, for example, alcohol or glucose.
If a sample of blood is to be analysed, the blood is placed in the sample bottle or cuvette 16, the sample bottle or cuvette 16 is mounted in the holder 11 , and the holder 11 is mounted to the aperture 10 in the integrating sphere. The sample within the bottle is thus exposed to the interior of the sphere, and will thus be exposed to the light that is directed into the sphere. Light from the light source 1 , passing through the filter 2 and the fibre optic bundle 9 is directed into the integrating sphere. The light may be focussed on to the blood sample within the sample bottle, and that light is effectively "reflected" into the interior of the sphere. Some wavelengths of light are reflected almost totally, but other wavelengths of light are partially, or sometimes completely, absorbed by the blood. The light that is reflected from the sample is consequently not of the same spectral content as the light entering the sphere.
The integrating sphere is, of itself, a known component. Light within an integrating sphere is uniformly reflected and scattered around the interior of the sphere, with the light sometimes effecting many multiple reflections and re-reflections. The interior of the sphere, whilst being "reflective" of light is not a "mirror" finish, but instead reflects light in a "diffuse" manner. The whole of the interior of the sphere is thus exposed to a substantially uniform illumination, and at any point on the surface of the sphere light will be present which has a spectral content which is determined by the light absorption/reflection characteristics of the sample in the sample bottle or cuvette 16.
Light having the specific spectral content will thus emerge from the integrating sphere through the aperture 17 and will pass into the light trap 20. The light passes to the spectroscope 21 , which performs a spectral analysis to provide data related to the intensity of light at a plurality of wavelengths.
It has now been found that it is possible to make qualitative or quantitative measurements with regards to specific components of a liquid sample using visible and near-infrared spectrometry. Using regressional methods with statistics it is possible to determine the presence of a specific component or chemical within a liquid sample and also possible to determine the concentration of that component or chemical within the sample. The relevant techniques, sometimes referred to a "chemometrics" involve many steps and methods, depending upon the nature of the data and how one step or method works over the other.
One technique that may be utilised is known as principal component analysis, which can be performed by analysing the intensities of light at a few selected wavelengths, the wavelengths being selected, of course, in dependence upon the nature of the specific component or chemical in the sample that is to be identified, and whose concentration is to be determined. The wavelengths are selected so that there will be no "interference" from other constituents of the liquid, such as water. Thus the wavelengths selected are wavelengths where a "peak" is expected to be if, and only if, a specific component or chemical is present.
In this technique, each of the wavelengths to be analysed is represented as a separate "dimension" in a notional poly-dimensional space.
If three wavelengths are selected as being relevant, the relative intensity of light of each selected wavelength is measured, as shown in Figure 2. The three intensities of light and three wavelengths may be shown on three separate lines, as shown in Figure 3. The three separate lines may form three orthogonal axis, as shown in Figure 4, and consequently, a single point, identified as the point O in Figure 5 can be defined, from the three measurements which have been taken. It is to be appreciated that if subsequent measurements of the further sample lead to a point line on the line 24 shown in Figure 5 which passes from the origin of the orthogonal space, and which passes through the point O than the present of a point on that line indicates the presence of the same substance that was in the sample initially tested, and the position on the line 24 indicates the concentration of the sample. The above explanation is, as will be understood, a very "simple" explanation relating to the situation that will be obtained if only three wavelengths are selected as being relevant. Of course, in any practical example a larger number of wavelengths will be selected and thus a multi-dimensional space will need to be created. Whilst this is difficult to visualise, such a multidimensional space can be created within a computer.
Also, of course, the explanation given above has been simplified and represents a "perfect" situation, where a second sample, when analysed spectroscopically in the manner described, generates a point in the multidimensional space which lies on the line 24. It has been found that such "perfect" results are seldom obtainable, but, nevertheless, by considering one or more points which are sufficiently close to the notional line, and by conducting statistical tests to confirm the statistical significance of the points, consistent and accurate results can be obtained.
A further technique that may be utilised involves Fourier analysis of the sometimes complex initial output of the spectroscope, the Fourier analysis being intended to identify underlying "wave forms" which make up the complex "wave form" of the spectroscope output. The Fourier analysis may identify several underlying "wave forms", each with a different amplitude. Each of those "wave forms" may be representative of a particular component of the sample and the amplitude of the wave form is representative of the concentration of that component within the sample.
It is to be understood, therefore, that the processor 20 may utilise many different techniques to process the data from the spectral analysis, and the processor will operate to determine the presence of, and also the concentration of, at least one predetermined component within the sample. As mentioned above if the sample is a blood sample the processor may be programmed to determine the concentration of alcohol in the blood or the concentration of glucose in the blood or the concentration of any other blood component that is of interest. The processor may therefore perform the necessary processing steps to produce an output which is indicative of the presence of and the concentration of a large number of potential components in the sample.
The processor provides an output to a display device or printer 23 which gives a visible indication of the results produced by the processor. Thus a "screen" or printout may be provided which indicates the presence of one or more components in the blood, giving the concentration of each component. The components may be alcohol, glucose, haemoglobin, sodium, potassium or other components that may be of interest.
Consequently it is to be understood that in using the apparatus of Figure 1 to perform the above described method a sample of a liquid, which may be opaque, such as blood, may be inserted into a sample bottle or cuvette 16, the sample bottle or cuvette 16 may be mounted to the integrating sphere 3, and subsequently the spectroscope will analyse light emerging from the integrating sphere with the output of the spectroscope being processed by a processor to determine the light absorption/reflection characteristics to be determined and processed to enable a display to display information (or a printer to print information), that information including an indication of the presence of and the concentration of specific components in the blood. The entire process may be complete within a few moments, and with great repeatability and high accuracy.
Whilst the method has been described, with reference to Figure 1 , in the context of opaque liquid, the method may be formed using a substantially
"transparent" liquid, such as a clear aqueous solution. If a liquid of this type is to be used the side of the cuvette or sample bottle 16 which is furthest from the aperture 10, or the inner face of the upstanding wall 14 of the sample holder may be provided with a "reflective" coating equivalent to the reflective coating provided on the interior of the integrating sphere, or in the form of a mirror-like coating.
It is to be appreciated that in the embodiment of Figure 1 only a relatively small area of the sample under investigation is exposed to the interior of the integrating sphere. Reference is now made to Figure 6 of the accompanying drawings which shows a modified embodiment of the invention. Many of the components of this embodiment are the same as the embodiment of Figure 1 and these components will not be re-described.
In the embodiment illustrated in Figure 6, the aperture 10 in the sphere is replaced by a relatively large aperture 30. The sample bottle 16 is replaced by a sample container 31. The sample container 31 is provided with a discshaped upper part 32 which carries a central axially extending chamber 33, that chamber terminating with a concave wall 34, the concave wall 34 having a radius of curvature substantially equal to the radius of curvature of the integrating sphere. The sample container 31 is mounted to the aperture 30 by means of a mounting collar 35, the mounting collar 35 having an internally threaded ring 36 to engage threading provided on the exterior of the aperture 30 and an inwardly directed flange 37, the flange being configured to overlie the disc-shaped part 32 of the sample container 31.
It is to be appreciated that when the sample container 31 has been mounted to the aperture 30 and retained in place by the mounting collar 35, the concave face 34 of the sample container 31 is substantially aligned with interior of the sphere, so that the interior of the sphere and the concave face 34 of the sample container 31 is a smooth, virtually unbroken, uniformly curved part of a spherical surface, thus facilitating the even and uniform reflection and diffusion of light within the integrating sphere.
If the liquid to be contained within the sample container 31 is to be transparent, then the uppermost wall of the disc-shaped part of the sample container, the wall 35, may be provided with a reflective coating which may be equivalent to the reflective coating provided within the integrating sphere, or which may be a mirror-like reflective coating.
While embodiments of the invention have been described in which the sample holder is provided with a reflective coating to provide a reflective property, so that light is reflected back through the sample to re-enter the integrating sphere, in other embodiments a light absorbing coating may be provided to give a light absorbing property, so that any light passing through the sample is totally absorbed. The said coatings may be present on separate elements, such as plates, configured to be brought into engagement with the appropriate parts of the sample bottle. Thus, if desired, the plates may both be put to one side, to provide the sample bottle with a light transmissive property, enabling light which has passed through the sample to emerge from the integrating sphere. This light may be spectrally analysed.
In a modified embodiment of the invention, the sample holder may be associated with a removable element in the form of a spectral filter. The spectral filter will allow light of selected wavelengths to be transmitted through the filter and/or reflected back into the sample holder.
Many different sets of data may be obtained from a single sample, using the light reflective and light absorbing plates, which may be used to enhance the accuracy of the analysing of the sample. The invention has been described primarily with reference to embodiments in which the sample is provided at an aperture which is spaced from the light inlet. In a modified embodiment the sample may be provided at the light inlet, thus being positioned between the light source and the integrating sphere so that the light passes through the sample before entering the light integrating sphere. If the sample is provided at the light inlet it may need to be in a sample holder with parallel straight walls to avoid unwanted reflections from, for example, a concave wall.
In the described embodiments the light source is a source which provides a constant uniform intensity light. However, the source may be a pulsed source. The spectroscopic analysis may be performed shortly after the end of each input pulse of light. Successive input pulses may have different spectral contents. Some pulses may be substantially monochromatic, but other pulses may contain specific selected wavelengths of light. The light may be polarised, being either plane polarised or circular polarised.
When used in this Specification and Claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.
The features disclosed in the foregoing description, or the following Claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

Claims
1. A method of determining the concentration of at least one component in a liquid sample, the method comprising the steps of directing light from a light source into an integrating sphere, mounting a sample holder containing the liquid sample to or adjacent the integrating sphere, to expose the sample to the light, withdrawing light from the sphere, performing a spectral analysis on the light to provide data relating to the intensity of light at least at certain predetermined wavelengths, processing the data from the spectral analysis to determine the presence of and concentration of said at least one component and displaying or printing information generated during the processing step.
2. A method according to Claim 1 wherein the light has a predetermined spectral range.
3. A method according to Claim 1 wherein the light has a substantial component in the near-infrared range.
4. A method according to any one of the preceding Claims in which the light source is pulsed to give successive pulses of light.
5. A method according to Claim 4 wherein the step of withdrawing light from the sphere is effected after the end of a pulse of light.
6. A method according to Claim 4 or 5 wherein successive pulses of light have a different spectral content.
7. A method according to any one of the preceding Claims wherein the light directed into the integrating sphere is polarised.
8. A method according to any one of the preceding Claims wherein the liquid is transparent to at least part of the frequency spectrum of the light and the sample holder is mounted between the light source and the integrating sphere so the light passes through the sample before entering the sphere.
9. A method according to any one of Claims 1 to 9 wherein the sample holder is mounted to the integrating sphere to expose the sample to light within the sphere.
10. A method according to Claims 9 wherein the light directed into the integrating sphere is focussed on to the sample.
11. A method according to Claim 9 or 10 comprising the step of adjusting the optical characteristic of the sample holder by altering the reflectance/absorbence/transmittance of part of the sample holder remote from the interior of the integrating sphere.
12. A method according to any one of the preceding Claims wherein the liquid is opaque to at least part of the frequency spectrum of the light.
13. A method according to any one of the preceding Claims wherein the liquid is blood.
14. A method according to any one of the preceding Claims wherein the component is selected from the group comprising alcohol, glucose, haemoglobin, sodium, or potassium.
15. An apparatus for performing spectral analysis of a liquid sample, the apparatus comprising an integrating sphere, the integrating sphere having a light inlet and a light outlet, the integrating sphere having an aperture to receive a sample container, there being a sample container engageable with the aperture, the sample container having a convex wall, the convex wall having a radius of curvature substantially equal to that of the interior of the integrating sphere, the arrangement being such that when the sample container is mounted to the integrated sphere the convex wail of the sample container is substantially aligned with the interior of the sphere.
16. An apparatus according to Claim 10 wherein the aperture to receive the sample container is the light inlet.
17. An apparatus according to claim 10 wherein the aperture to receive the sample container is spaced from the light inlet.
18. An apparatus according to Claim 17 wherein part of the sample container remote from the convex wall is provided with a light reflective property.
19. An apparatus according to Claim 17 wherein part of the sample container remote from the convex wall is provided with a light absorbent property.
20. An apparatus according to Claim 17, 18, or 19 wherein part of the sample container remote from the convex wall is provided with a light transmissive property.
21. An apparatus for performing spectral analysis of a liquid sample, the apparatus comprising an integrating sphere, the integrating sphere having a light inlet and a light outlet and having an aperture spaced from the light inlet to receive a sample container to expose a sample in the sample container to light in the integrating sphere, a part of the sample container having a light reflective on a light absorbent property.
22. An apparatus according to any one of Claims 18 to 21 wherein the sample container is associated with a removable element, the element providing the light reflective or a light absorbence property.
23. An apparatus according to Claim 22 wherein the removable element is in the form of a spectral filter.
24. An apparatus according to Claim 15 and substantially as herein described with reference to and as shown in Figures 6 and 7 of the accompanying drawings.
25. Any novel feature or combination of features disclosed herein.
PCT/GB2006/002368 2005-06-27 2006-06-27 A method of spectral analysis and an apparatus for performing the method WO2007000592A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP06755652A EP1949080A1 (en) 2005-06-27 2006-06-27 A method of spectral analysis and an apparatus for performing the method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0513063.8 2005-06-27
GB0513063A GB0513063D0 (en) 2005-06-27 2005-06-27 A method of spectral analysis and an apparatus for performing the method

Publications (1)

Publication Number Publication Date
WO2007000592A1 true WO2007000592A1 (en) 2007-01-04

Family

ID=34856204

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2006/002368 WO2007000592A1 (en) 2005-06-27 2006-06-27 A method of spectral analysis and an apparatus for performing the method

Country Status (3)

Country Link
EP (1) EP1949080A1 (en)
GB (1) GB0513063D0 (en)
WO (1) WO2007000592A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103115880A (en) * 2013-01-18 2013-05-22 山东大学 Spectral analysis method with laser-induced auditory nerve
CN103837520A (en) * 2014-03-03 2014-06-04 上海理工大学 Optic travelling wave cavity enhanced laser raman gas concentration detection device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201100279D0 (en) 2011-01-10 2011-02-23 Murwillumbah Mfg Spectral analysis apparatus and method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10213481A (en) * 1997-01-27 1998-08-11 Toppan Printing Co Ltd Liquid color measuring device and method for correcting color of colored liquid
WO2000013002A2 (en) * 1998-08-27 2000-03-09 Abbott Laboratories Reagentless analysis of biological samples
JP2002243550A (en) * 2001-02-20 2002-08-28 Minolta Co Ltd Optical characteristic measuring device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10213481A (en) * 1997-01-27 1998-08-11 Toppan Printing Co Ltd Liquid color measuring device and method for correcting color of colored liquid
WO2000013002A2 (en) * 1998-08-27 2000-03-09 Abbott Laboratories Reagentless analysis of biological samples
JP2002243550A (en) * 2001-02-20 2002-08-28 Minolta Co Ltd Optical characteristic measuring device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103115880A (en) * 2013-01-18 2013-05-22 山东大学 Spectral analysis method with laser-induced auditory nerve
CN103837520A (en) * 2014-03-03 2014-06-04 上海理工大学 Optic travelling wave cavity enhanced laser raman gas concentration detection device

Also Published As

Publication number Publication date
EP1949080A1 (en) 2008-07-30
GB0513063D0 (en) 2005-08-03

Similar Documents

Publication Publication Date Title
US9448161B2 (en) Optical device, particularly a polarimeter, for detecting inhomogeneities in a sample
DE60222864T2 (en) METHOD AND DEVICE FOR STUDYING FLUIDS
ES2359968T3 (en) SPECTROPHOTOMETRIC AND NEFELOMETRIC DETECTION UNIT.
US9052232B2 (en) Spheroid sample cell for spectrometer
WO2012095651A1 (en) Analysis apparatus and method
JP2000009638A (en) Spectral analyzer and method by means of reflectivity and permeability, and probe for spectrometer
JP2006322841A (en) Spectrometry and spectrophotometer
EP2477024B1 (en) Analyzer
CA2565172C (en) A portable device and method for on-site detection and quantification of drugs
WO2007000592A1 (en) A method of spectral analysis and an apparatus for performing the method
JP6785843B2 (en) Equipment and methods for performing light absorption measurements on test samples and compliance measurements on reference samples
US20230218174A1 (en) Spectral analysis of a sample
US6147350A (en) Spectroscopic residue detection system and method
JPH0989775A (en) Spectroscopic measuring apparatus and automatic analyzer
US20230175953A1 (en) Device and method for spectral analysis of a compound specimen
US9683927B2 (en) Device for receiving small volume liquid samples
CN217155593U (en) Sample preposed optical system of spectrophotometer
CN212255059U (en) Spectrophotometry detection system with all-in-one light source
CN111323406A (en) Portable Raman probe with distributed focusing function
Noble Illuminating near-IR
Yoon et al. Spectrophotometry
EP0574601A1 (en) Improved method and apparatus for optical interactance and transmittance measurements
CN218382403U (en) PCR optical detection assembly
CN208283265U (en) Multifunctional optical fiber probe and water quality detecting device
Hammond Four Generations of Quality: a spectroscopic trio

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Country of ref document: DE

WWE Wipo information: entry into national phase

Ref document number: 2006755652

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2006755652

Country of ref document: EP