DE102004053480B3 - Photo-acoustic process for analysis and determination of concentration of sample liquid by comparison with reference sample - Google Patents
Photo-acoustic process for analysis and determination of concentration of sample liquid by comparison with reference sample Download PDFInfo
- Publication number
- DE102004053480B3 DE102004053480B3 DE200410053480 DE102004053480A DE102004053480B3 DE 102004053480 B3 DE102004053480 B3 DE 102004053480B3 DE 200410053480 DE200410053480 DE 200410053480 DE 102004053480 A DE102004053480 A DE 102004053480A DE 102004053480 B3 DE102004053480 B3 DE 102004053480B3
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- radiation
- cell
- measuring cell
- sample
- sound wave
- Prior art date
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Classifications
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- 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
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/12—Analysing solids by measuring frequency or resonance of acoustic waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/222—Constructional or flow details for analysing fluids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/223—Supports, positioning or alignment in fixed situation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor
- G01N29/38—Detecting the response signal, e.g. electronic circuits specially adapted therefor by time filtering, e.g. using time gates
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/021—Gases
- G01N2291/0215—Mixtures of three or more gases, e.g. air
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0421—Longitudinal waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/045—External reflections, e.g. on reflectors
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- Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
Die Erfindung betrifft ein photoakustisches Verfahren zur Analyse und Konzentrationsmessung gemäß dem Oberbegriff des Patentanspruchs 1.The The invention relates to a photoacoustic method for analysis and Concentration measurement according to the preamble of claim 1
Als
nächstkommender
Stand der Technik sind die
Der neue unabhängige Anspruch 1 löst in bezug auf den nächstkommenden Stand der Technik die Aufgabe, Analysen und Konzentrationsmessungen mit höherer Nachweisempfindlichkeit unter Verwendung eines kompakteren Aufbaus zu ermöglichen.Of the new independent Claim 1 solves in relation to the nearest one State of the art task, analyzes and concentration measurements with higher Detection sensitivity using a more compact design to enable.
Die
Messmethode der Photoakustischen Spektroskopie (PAS) beruht auf
der Tatsache, dass die Energie absorbierter Strahlung teilweise
durch strahlungslose Relaxation in thermische Energie der umliegenden
Moleküle
umgewandelt wird. Dies hat eine Erhöhung des Drucks in der Probe
zur Folge. Durch eine modulierte Einstrahlung entsteht eine akustische
Welle, die mit einem Schallaufnehmer detektiert und dann phasenempfindlich
gemessen wird. Die Nachweisempfindlichkeit eines photoakustischen Sensors
ist primär
bestimmt durch das Signal-zu-Rausch-Verhältnis. Der
Absolutbetrag des photoakustischen Signals SPAS kann
beschrieben werden durch
Gemäß Anspruch 1 wird in der Messzelle eine solche akustische Resonanz angeregt. Die Detektion der Schallwelle erfolgt dann nicht wie sonst üblich mit einem zentrisch an der Messzelle montierten Schallaufnehmer sondern am Ort einer konstruktiven Interferenz der gewählten Resonanz. Typische Messzellmaterialien stellen schallharte Begrenzungen dar, sodass konstruktive Interferenz für die longitudinale Resonanz erster Ordnung an den Enden der Messzelle auftreten. Nur dort ist die Signalüberhöhung besonders effizient. Die Zellkonstante wird besonders groß und die Nachweisempfindlichkeit erfindungsgemäß besonders hoch. Da radiale und azimuthale Resonanzen nur in Zellen mit großen Durchmessern angeregt werden können, erlaubt diese Maßname besonders kompakte Sensoren.According to claim 1, such an acoustic resonance is excited in the measuring cell. The detection of the sound wave is then not as usual with a centrally mounted on the measuring cell transducer but at the site of a constructive interference of the chosen resonance. Typical measuring cell materials represent reverberant boundaries, so constructive interference for the longitudinal first order resonance at the ends of the measuring cell occur. Only there is the signal overshoot particularly efficient. The Cell constant becomes particularly large and the detection sensitivity particularly according to the invention high. Because radial and azimuthal resonances only in cells with large diameters can be stimulated allows this measure name especially compact sensors.
Gemäß einer vorteilhaften Ausgestaltung wird eine longitudinale Resonanz in einer zylindrischen Messzelle angeregt, die spiralförmig aufgewickelt ist. Diese Maßname spart Platz und ermöglicht ebenfalls besonders kompakte Sensoren.According to one advantageous embodiment is a longitudinal resonance in a cylindrical measuring cell excited spirally wound is. This measure name saves space and also allows especially compact sensors.
Eine vorteilhafte Ausgestaltung der Erfindung sieht vor, dass die Strahlung am Ort einer konstruktiven Interferenz durch die Messzelle geführt wird. Die die Strahlung absorbierenden Moleküle stellen die Schallquelle für das photoakustische Signal dar. Findet die Erzeugung des Signals am Ort einer konstruktiven Interferenz statt, ist die Anregung der akustischen Resonanz besonders effizient. Dies erlaubt ebenfalls empfindlichere Konzentrationsmessungen.A advantageous embodiment of the invention provides that the radiation is passed through the measuring cell at the site of a constructive interference. The molecules absorbing the radiation are the sound source for the photoacoustic signal. Finds the generation of the signal at Place of a constructive interference, is the suggestion of acoustic resonance particularly efficient. This also allows more sensitive concentration measurements.
Eine andere Ausgestaltung sieht vor, dass die Messzelle aus zwei senkrecht zueinander stehenden Zylindern gefertigt ist, von denen der eine den Resonator für die Anregung der akustischen Resonanz bildet sowie den Schallaufnehmer beinhaltet und der andere die Absorptionsstrecke für die Strahlung darstellt. Diese Zelle erlaubt die voneinander unabhängige Anpassung dieser beiden Schlüsselparameter. Sie erlaubt längere Absorptionswege, auch wenn der Resonator nur einen kleinen Querschnitt besitzt und ermöglicht so größere Signale und erfindungsgemäß höhere Nachweisempfindlichkeiten.A Another embodiment provides that the measuring cell from two vertically made to each other standing cylinders, one of which is the Resonator for the excitation of the acoustic resonance forms as well as the sound pickup and the other the absorption path for the radiation represents. This cell allows independent adaptation of these two key parameters. It allows longer Absorption pathways, even if the resonator has only a small cross-section and allows so bigger signals and higher detection sensitivities according to the invention.
Gemäß einer weiteren vorteilhaften Ausgestaltung wird die Strahlung durch eine Messzelle gelenkt wird, die mit Puffervolumina zur Reduzierung externen Schalls ausgestattet ist. Dies erlaubt ebenfalls höhere Nachweisempfindlichkeiten.According to one Another advantageous embodiment, the radiation is by a Measuring cell is directed, with buffer volumes for reducing external Sound is equipped. This also allows higher detection sensitivities.
Auch das Detektieren des photoakustischen Signals mit mehreren Mikrofonen, die sich an Orten konstruktiver Interferenz befinden, erlaubt entsprechend einer Ausgestaltung eine Erhöhung der Sensitivität.Also detecting the photoacoustic signal with multiple microphones, which are in places of constructive interference allows accordingly an embodiment an increase the sensitivity.
Eine andere vorteilhafte Ausgestaltung der Erfindung sieht den Einsatz einer Referenzzelle vor. Diese kann zum Beispiel zur Kalibrierung dienen. Für eine akustisch resonante Anregung ist es erforderlich, dass Messzelle und Resonanzzelle die gleiche Geometrie besitzen.A Another advantageous embodiment of the invention provides the use a reference cell. This can be used for calibration, for example serve. For one Acoustically resonant excitation requires that the measuring cell and resonance cell have the same geometry.
Ein vorteilhafter Effekt lässt sich auch durch die Reflexion der Strahlung der Laserdiode mit Hilfe eines Spiegels hinter der Messzelle erreichen. Auf diese Weise wird die Zelle ein zweites Mal durchstrahlt. So lassen sich durch vergrößerte Absorptionen die Signale erhöhen, und damit die Nachweisgrenzen senken. Durch mehrfache Reflexion mittels weiterer Spiegel oder verspiegelter Zellen lässt sich dieser Effekt noch steigern.One advantageous effect also by the reflection of the radiation of the laser diode with the help of a Reach mirror behind the measuring cell. In this way, the Radiates the cell a second time. This can be achieved by increased absorption increase the signals, and thus lower the detection limits. Through multiple reflection By means of further mirrors or mirrored cells can be this Increase the effect even more.
Ein Ausführungsbeispiele der Erfindung sind in den Zeichnungen dargestellt.One embodiments The invention are illustrated in the drawings.
Die mit der Erfindung erzielten Vorteile bestehen insbesondere darin, mit einem kompakteren Aufbau Analysen und Konzentrationsmessungen mit höherer Nachweisempfindlichkeit zu ermöglichen.The particular advantages of the invention are with a more compact design analyzes and concentration measurements with higher Detection sensitivity to allow.
Claims (10)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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DE200410053480 DE102004053480B3 (en) | 2004-11-05 | 2004-11-05 | Photo-acoustic process for analysis and determination of concentration of sample liquid by comparison with reference sample |
Applications Claiming Priority (1)
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DE200410053480 DE102004053480B3 (en) | 2004-11-05 | 2004-11-05 | Photo-acoustic process for analysis and determination of concentration of sample liquid by comparison with reference sample |
Publications (1)
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DE102004053480B3 true DE102004053480B3 (en) | 2006-04-20 |
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DE200410053480 Expired - Fee Related DE102004053480B3 (en) | 2004-11-05 | 2004-11-05 | Photo-acoustic process for analysis and determination of concentration of sample liquid by comparison with reference sample |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2256479A2 (en) | 2009-05-29 | 2010-12-01 | RWE Rhein-Ruhr Netzservice GmbH | Method for detecting multiple substances of a gas mixture by means of subsequent determination of individual substance concentrations |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4200399A (en) * | 1978-11-20 | 1980-04-29 | General Motors Corporation | Resonant optoacoustic spectroscopy apparatus |
DE3322870A1 (en) * | 1982-07-03 | 1984-01-05 | Horiba Ltd., Kyoto | OPTOACOUSTIC MEASURING DEVICE FOR DETERMINING A PARTICLE CONCENTRATION |
DE4446723C2 (en) * | 1994-06-29 | 1997-03-13 | Hermann Prof Dr Harde | Device and method for measuring the concentration of a gas |
US6618148B1 (en) * | 2000-02-10 | 2003-09-09 | Southwest Sciences Incorporated | Acoustic resonance frequency locked photoacoustic spectrometer |
DE10308409A1 (en) * | 2003-02-27 | 2004-09-09 | Marcus Dr. Wolff | Measurement of concentration or concentration ratios of gas components, for potential use in breath analysis of a patient's digestion/metabolism, uses a structured laser beam where sound waves are detected and evaluated |
-
2004
- 2004-11-05 DE DE200410053480 patent/DE102004053480B3/en not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4200399A (en) * | 1978-11-20 | 1980-04-29 | General Motors Corporation | Resonant optoacoustic spectroscopy apparatus |
DE3322870A1 (en) * | 1982-07-03 | 1984-01-05 | Horiba Ltd., Kyoto | OPTOACOUSTIC MEASURING DEVICE FOR DETERMINING A PARTICLE CONCENTRATION |
DE4446723C2 (en) * | 1994-06-29 | 1997-03-13 | Hermann Prof Dr Harde | Device and method for measuring the concentration of a gas |
US6618148B1 (en) * | 2000-02-10 | 2003-09-09 | Southwest Sciences Incorporated | Acoustic resonance frequency locked photoacoustic spectrometer |
DE10308409A1 (en) * | 2003-02-27 | 2004-09-09 | Marcus Dr. Wolff | Measurement of concentration or concentration ratios of gas components, for potential use in breath analysis of a patient's digestion/metabolism, uses a structured laser beam where sound waves are detected and evaluated |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2256479A2 (en) | 2009-05-29 | 2010-12-01 | RWE Rhein-Ruhr Netzservice GmbH | Method for detecting multiple substances of a gas mixture by means of subsequent determination of individual substance concentrations |
DE102009023230A1 (en) | 2009-05-29 | 2010-12-02 | Pas-Analytik Gmbh | Method for detecting a plurality of substances of a gas mixture by a temporal successive determination of the individual concentration of the substances |
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