WO2004034038A1 - Cellule a echantillon - Google Patents

Cellule a echantillon Download PDF

Info

Publication number
WO2004034038A1
WO2004034038A1 PCT/GB2003/003148 GB0303148W WO2004034038A1 WO 2004034038 A1 WO2004034038 A1 WO 2004034038A1 GB 0303148 W GB0303148 W GB 0303148W WO 2004034038 A1 WO2004034038 A1 WO 2004034038A1
Authority
WO
WIPO (PCT)
Prior art keywords
sample
cell
windows
window
separation
Prior art date
Application number
PCT/GB2003/003148
Other languages
English (en)
Inventor
Gareth Jones
David Clarke
Original Assignee
Council For The Central Laboratory Of The Research
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 Council For The Central Laboratory Of The Research filed Critical Council For The Central Laboratory Of The Research
Priority to AU2003300492A priority Critical patent/AU2003300492A1/en
Publication of WO2004034038A1 publication Critical patent/WO2004034038A1/fr

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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • G01N21/05—Flow-through cuvettes
    • 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
    • G01N21/03—Cuvette constructions
    • G01N21/0303—Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment
    • 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
    • G01N21/03—Cuvette constructions
    • G01N2021/0346—Capillary cells; Microcells
    • 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
    • G01N21/03—Cuvette constructions
    • G01N2021/036—Cuvette constructions transformable, modifiable
    • 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
    • G01N21/21—Polarisation-affecting properties
    • G01N2021/216—Polarisation-affecting properties using circular polarised 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/11—Filling or emptying of cuvettes

Definitions

  • the present invention relates to a cell for holding a fluid sample whilst performing an optical measurement on the sample.
  • a sample cell comprises a chamber for receiving a volume of a fluid sample provided with windows for the transmission of light through the chamber/sample.
  • Such cells may comprise windows provided in an otherwise opaque cell body, or the entire cell may be constructed from a suitable transparent material such as quartz etc.
  • quartz a suitable transparent material
  • the signal to noise ratio arising from the radiation path length through the sample (ie width of the cell) and absorbance of the sample itself is critical to the measurement accuracy.
  • CD circular dichroism
  • the polarisation dependant absorption is only of the order of one part in 10 5 of the total absorbance of the sample.
  • the sample absorbance is itself dependent on the molar absorbance of the sample substance and of the optical path length through the sample cell.
  • the absorption is calculated as a function of the change in intensity of the light transmitted through the cell as measured by a detector positioned behind the cell.
  • the functional relationship is logarithmic and thus relatively small changes in absorbance can have a large effect on the intensity of light reaching the detector and thus on the accuracy of measurement.
  • the cell pathlength is therefore a very important factor to be considered in optimising measurements.
  • conventional cells there can be a significant variation in pathlength between two cells of supposedly the same dimension. The effect that this can have on the final measurement is exacerbated when the cells have a very short pathlength.
  • pathlength of the order of 10 ⁇ m
  • the actual pathlength of any given "10 ⁇ m" cell could be anywhere between about 6 and 15 ⁇ m which can have a significant detrimental impact on the measurement.
  • apparatus for use in performing an optical measurement on a fluid sample by detecting radiation transmitted through the sample, the apparatus comprising; a sample cell for receiving said fluid sample, the sample cell comprising first and second opposing windows defining a sample receiving space therebetween, the separation of mutually facing surfaces of the first and second windows defining an optical pathlength of the cell, the windows being relatively moveable to increase and decrease their separation; and feedback control means operable in use to control the separation of the first and second windows dependent upon the detected radiation to thereby adjust the optical pathlength to optimise the particular optical measurement being performed.
  • the apparatus according to the invention enables the optical path length to be dynamically and accurately adjusted to an optimum path length during the course of a measurement. For instance, this allows the pathlength to be optimised for different wavelengths of illuminating radiation or different sample compositions with differing absorbance properties. Moreover, by providing continuous feedback adjustment, the pathlength may be changed over the course of a measurement as for instance the illuminating wavelength is scanned over a range of wavelengths, or the sample composition changes, for instance as a result of a reaction occurring within the sample or the continuous flow of a changing sample stream through the cell.
  • a sample cell for receiving a fluid sample for use in an optical measurement to be performed on the sample, the cell comprising: a cell housing; first and second opposing windows supported within the cell housing and defining a sample receiving space therebetween, the separation of mutually facing surfaces of the first and second windows defining an optical pathlength of the cell, wherein the second window is slidably mounted within the cell housing and drive means are provided for sliding the second window towards and away from the first window to increase or decrease said separation thereby varying the optical pathlength of the cell.
  • this instruction provides for accurate positioning of the window at very small path lengths of the order of several ⁇ m.
  • This is not for instance possible with certain prior art adjustable volume cells which comprise a moveable window screwed into a cylindrical housing. With such arrangements tolerances in the screw thread give rise to variations in the precise orientation of the window as it moves back and forth. Whilst such variations must be small and thus of little significance at relatively large path lengths, at smaller path lengths of the order of several ⁇ m the positional errors can be significant.
  • the present invention also provides a method of performing an optical measurement on a fluid sample, the method comprising: a method of performing an optical measurement on a fluid sample, the method comprising; containing said sample within a sample cell comprising first and second opposing windows defining a sample receiving space therebetween, the separation of mutually facing surfaces of the first and second windows defining an optical pathlength of the cell; illuminating the sample through said first window; detecting radiation transmitted through said sample and through said second window; controlling the separation of the first and second windows dependent upon the detector response to thereby adjust the optical pathlength to optimise the detector response for the particular measurement being performed.
  • the method is particularly advantageous when applied to the measurement of CD where measurement accuracy has a high dependence on optical pathlength through the cell.
  • Figure 1 is a schematic overview of a sample cell assembly in accordance with the present invention
  • Figure 2 is a schematic cross-section of one embodiment of a sample cell in accordance with the present invention.
  • a sample cell comprises front and back window elements 1 and 2 defining a sample volume therebetween.
  • Incident light (or other radiation) for performance of an optical measurement enters the cell through the front window 1 and leaves through the back window 2 (as indicated by arrows L).
  • the intensity of transmitted light is detected at detector 3.
  • the optical pathlength of the cell is the separation of the internal surfaces of the front and back windows 1 and 2.
  • the back window element 2 is moveable towards and away from the front window element 1 to vary the cell pathlength. Movement of the back window 2 is effected by a motor 4 under the control of a processing unit 5 in response to the intensity of radiation detected at the detector 3. Specifically, feedback from the detector 3 is used to adjust the pathlength of the cell to provide optimum measurement accuracy given any particular sample type or wavelength of light used to illuminate the sample.
  • variable pathlength cell will be of significant advantage wherever the accuracy of the measurement performed is highly dependent on the cell pathlength. For instance the cell will be particularly useful in CD measurements.
  • measurements are taken across a range of wavelengths (typically 240 nm to 190 nm) as CD is wavelength dependent.
  • wavelengths typically 240 nm to 190 nm
  • the pathlength can be continuously adjusted through feedback from the detector to enable measurement across the whole range of desired wavelengths without the need to actually change the cell.
  • the cell according to the present invention could be configured as a flow cell through which different samples are continuously passed.
  • rapid and continuous feedback from the detector enables optimisation of the pathlength as different samples flow through the cell to provide high-throughput measurement capabilities.
  • the present invention also overcomes problems associated with the loading of conventional cells. For instance, with short pathlength conventional cells it is not possible to inject a sample liquid into the cell volume and the usual loading technique is to introduce a droplet of the sample to the cell space and rely on capillary force to take up the sample which may not always be uniform. However, with the present invention the space between the window elements can be opened up as far as is necessary to allow injection of the sample fluid.
  • the pathlength could be increased to in excess of 1cm to enable the fluid to be injected without distorting the windows.
  • difficulties with loading the cell impose a practical minimum pathlength limitation of the order of 10 ⁇ m with conventional cells.
  • the cell can be filled and the pathlength reduced to the order of 1 ⁇ m or less. This broadens the range of measurement that may be made using the cell. For instance when conducting circular CD measurements it extends the available wavelength range down to of the order of 130 nm.
  • the change in pathlength could also be achieved by moving the front window element, or indeed both window elements. It will also be appreciated that data collection will be inhibited as the window element (or elements) is being moved during which time the pathlength is changing.
  • any suitable means could be used to determine the position of the moveable window element (or elements), and measure changes in the pathlength.
  • encoded stepper motors which are accurate to the order of 1 ⁇ m are commercially available.
  • the pathlength could be calibrated from a laser induced interference pattern given from an empty side panel of the cell.
  • Other appropriate instruments/techniques will be apparent to the skilled person.
  • the illustrated cell comprises a cylindrical cell body 6 with a fixed front window 7 and a moveable back window 8.
  • the back window 8 is slidably mounted between sides of the body 6 on a pusher ring 9.
  • the pusher ring 9 is itself slidably sealed with respect to the body 6, for instance by providing the surface of the pusher ring with a PTFE coating. Movement and positioning of the window 8 is controlled by an encoded stepper motor 10 which acts on the pusher ring 9 via a rotatable collar 11 which is in screw threaded engagement with the cell body 6.
  • encoded stepper motor 10 which acts on the pusher ring 9 via a rotatable collar 11 which is in screw threaded engagement with the cell body 6.
  • encoders which can be used in this application.
  • Sample fluid is introduced into the cell from a reservoir 12 positioned to one side of the cell. This allows fluid to flow freely into and out of the cell as the volume of the cell changes with adjustment of the pathlength.
  • the reservoir is positioned to one side of the cell rather than above the cell to avoid exerting a pressure head which might tend to distort the windows 7 and 8.
  • the present invention provides four major advantages over conventional sample cells. Firstly it enables accurate control of the pathlength; secondly it enables the pathlength to be optimised to suit different samples or optical wavelengths; thirdly it overcomes problems associated with loading short pathlength conventional cells; and fourthly it enables provision of cells with a much smaller pathlength than has previously been readily achievable.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Optical Measuring Cells (AREA)

Abstract

L'invention concerne un appareil et un procédé permettant d'effectuer une mesure optique sur un échantillon de fluide, par détection d'un rayonnement émis à travers cet échantillon. L'appareil selon l'invention comprend une cellule à échantillon (1, 2) pourvue d'une fenêtre mobile (2) servant à ajuster la longueur du chemin optique à travers la cellule. Cet appareil est en outre doté d'un moyen de commande par rétroaction (5) conçu pour commander la séparation desdites fenêtres, afin d'optimaliser la longueur de chemin instantanée pour ladite mesure optique.
PCT/GB2003/003148 2002-10-10 2003-07-24 Cellule a echantillon WO2004034038A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003300492A AU2003300492A1 (en) 2002-10-10 2003-07-24 Sample cell

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0223546.3 2002-10-10
GB0223546A GB0223546D0 (en) 2002-10-10 2002-10-10 Sample cell

Publications (1)

Publication Number Publication Date
WO2004034038A1 true WO2004034038A1 (fr) 2004-04-22

Family

ID=9945654

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/003148 WO2004034038A1 (fr) 2002-10-10 2003-07-24 Cellule a echantillon

Country Status (3)

Country Link
AU (1) AU2003300492A1 (fr)
GB (1) GB0223546D0 (fr)
WO (1) WO2004034038A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008011393A2 (fr) * 2006-07-20 2008-01-24 Sas Photonics, Llc système et procédé pour une analyse optique
EP1956358A1 (fr) * 2007-02-07 2008-08-13 FOSS Analytical AB Porte-échantillons
WO2009039920A1 (fr) * 2007-09-20 2009-04-02 Technische Universität München Système, procédé et détecteur pour la détection de paramètres d'un liquide
GB2486435A (en) * 2010-12-14 2012-06-20 Morteza Bahrami Liquid sample receiving apparatus
WO2017060159A1 (fr) * 2015-10-07 2017-04-13 Pyreos Ltd. Spectromètre à absorption
CN106645231A (zh) * 2016-12-27 2017-05-10 中国科学院山西煤炭化学研究所 一种光程连续可调的催化剂动态结构原位表征装置及应用
CN114199795A (zh) * 2021-10-26 2022-03-18 中国科学院深圳先进技术研究院 水下吸光光度计及水质检测方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4786171A (en) * 1986-07-29 1988-11-22 Guided Wave, Inc. Spectral analysis apparatus and method
US5371020A (en) * 1991-09-19 1994-12-06 Radiometer A/S Method of photometric in vitro determination of the content of an analyte in a sample
DE10016023A1 (de) * 2000-03-31 2001-10-18 Glukomeditech Ag Optische Vorrichtung zur gleichzeitigen Mehrfachmessung mittels Polarimetrie und Spektrometrie sowie Verfahren zur Regelung/Überwachung physikalisch-chemischer und biotechnischer Prozesse mittels dieser Vorrichtung

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4786171A (en) * 1986-07-29 1988-11-22 Guided Wave, Inc. Spectral analysis apparatus and method
US5371020A (en) * 1991-09-19 1994-12-06 Radiometer A/S Method of photometric in vitro determination of the content of an analyte in a sample
DE10016023A1 (de) * 2000-03-31 2001-10-18 Glukomeditech Ag Optische Vorrichtung zur gleichzeitigen Mehrfachmessung mittels Polarimetrie und Spektrometrie sowie Verfahren zur Regelung/Überwachung physikalisch-chemischer und biotechnischer Prozesse mittels dieser Vorrichtung

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008011393A2 (fr) * 2006-07-20 2008-01-24 Sas Photonics, Llc système et procédé pour une analyse optique
WO2008011393A3 (fr) * 2006-07-20 2008-05-15 Sas Photonics Llc système et procédé pour une analyse optique
GB2453293A (en) * 2006-07-20 2009-04-01 Sas Photonics Llc System and method for optical analysis
US7582869B2 (en) 2006-07-20 2009-09-01 Sas Photonics, Llc System and method for optical analysis
GB2453293B (en) * 2006-07-20 2011-02-16 Sas Photonics Llc System and method for optical analysis
EP1956358A1 (fr) * 2007-02-07 2008-08-13 FOSS Analytical AB Porte-échantillons
WO2008095914A1 (fr) * 2007-02-07 2008-08-14 Foss Analytical Ab Dispositif de support d'échantillon
WO2009039920A1 (fr) * 2007-09-20 2009-04-02 Technische Universität München Système, procédé et détecteur pour la détection de paramètres d'un liquide
GB2486435A (en) * 2010-12-14 2012-06-20 Morteza Bahrami Liquid sample receiving apparatus
WO2017060159A1 (fr) * 2015-10-07 2017-04-13 Pyreos Ltd. Spectromètre à absorption
CN106645231A (zh) * 2016-12-27 2017-05-10 中国科学院山西煤炭化学研究所 一种光程连续可调的催化剂动态结构原位表征装置及应用
CN114199795A (zh) * 2021-10-26 2022-03-18 中国科学院深圳先进技术研究院 水下吸光光度计及水质检测方法

Also Published As

Publication number Publication date
AU2003300492A1 (en) 2004-05-04
GB0223546D0 (en) 2002-11-20

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