CA1186402A - Flow type photoacoustic detector - Google Patents
Flow type photoacoustic detectorInfo
- Publication number
- CA1186402A CA1186402A CA000387513A CA387513A CA1186402A CA 1186402 A CA1186402 A CA 1186402A CA 000387513 A CA000387513 A CA 000387513A CA 387513 A CA387513 A CA 387513A CA 1186402 A CA1186402 A CA 1186402A
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- Prior art keywords
- flow
- detector
- cell
- liquid
- flow line
- Prior art date
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- 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
- G01N29/24—Probes
- G01N29/2418—Probes using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics
- G01N29/2425—Probes using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics optoacoustic fluid cells therefor
-
- 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
- G01N29/02—Analysing fluids
- G01N29/032—Analysing fluids by measuring attenuation 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
- G01N29/223—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
- G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
- G01N29/346—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with amplitude characteristics, e.g. modulated signal
-
- 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
- G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
- G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
-
- 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
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/46—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by spectral analysis, e.g. Fourier analysis or wavelet analysis
-
- 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
- G01N2291/10—Number of transducers
- G01N2291/102—Number of transducers one emitter, one receiver
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Immunology (AREA)
- Chemical & Material Sciences (AREA)
- Pathology (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Optics & Photonics (AREA)
- Acoustics & Sound (AREA)
- Mathematical Physics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
ABSTRACT
A flow type photoacoustic detector for measuring the optical sound of a liquid sample which includes a sample cell having inlet and outlet ports for continuous flow of liquid therethrough, a window plate and a pulsating source of high intensity light for irradiating the liquid flowing through the cell, and a piezoelectric sensor in direct acoustic contact with the liquid for measuring the optical sound generated. The liquid flow line is arranged so that the light will pass through a length of the sample substantially larger than the diameter of the inlet and outlet dimensions.
A flow type photoacoustic detector for measuring the optical sound of a liquid sample which includes a sample cell having inlet and outlet ports for continuous flow of liquid therethrough, a window plate and a pulsating source of high intensity light for irradiating the liquid flowing through the cell, and a piezoelectric sensor in direct acoustic contact with the liquid for measuring the optical sound generated. The liquid flow line is arranged so that the light will pass through a length of the sample substantially larger than the diameter of the inlet and outlet dimensions.
Description
36-9L0%
Detailed Description of the Invention This invention relates to a detector for measuring the photoacoustic output generated by a liquid sample which is irradiated by light. The liquid sample may be flowing through a cell while being irradiated. The invention also relates to a detector in which the liquid sample is allowed to flow through a flow cell equipped with pressure sensing means.
In this apparatus, intense light such as a laser beam irradiates the liquid sample in flowing state and the photoacoustic output generated by the liqu~d sample is measured to indicate the solute components in the liquid sample, without destroying the solute components and with high sensitivity. In general, a material, which has absorbed light, emits fluorescent light or exhibits a photoacoustic response, as shown in the following schema:
fluorescent absorption light _~
light ~ material sample - _ photoacoustic output Among these three processes, the light absorption process and the fluorescent light emission process are utilized practically for detecting changes in a flowing liquid such as in a high-performance liquid chromatographic detector. The light absorption process is used in both ultra-violet or visible light absorption detectors and the fluorescent emission uses a fluorescent light detector. In the absorption process the ratio of absorbed light to amount of light not absorbed by a material sample is measured. However, in the fluorescent light process or photoacoustic process the background light is approximately zero when the material sample does not emit fluorescent light or photoacoustic output, and thus it may be expected that highly sensitive measurement can be obtained compared to a material sample capable of emitting fluorescent light or photoacoustic output. In Eact, fluorescent light detectors are available for measuring fluorescent materials with high accuracy, but there ~Y~
~86~)Z
is a problem in that the number of fluorescen~ materials is limited.
It is therefore expected that photo-acoustic measurement can be applied to many materials with high accuracy for example for in case liquid chromatography etc., if the photoacoustlc measurement can be carried out while the materials are flowing. Such photoacoustic detection may be used either singly or in combination with fluorescence measurements. So far, the method of the photo-acoustic de~ection has been applied to many gas samples and solid samples, using condenser microphones as a sensor.
However, this method can not be applied to volatile materials, and 18 moreover water vapor is harmful to condenser microphones. This method has heretofore been applied to only a small number of liquid samples. In addition, no report has been made of using the photoacoustic detection for flowing liquid samples as encountered in high-performance liquid chromatography, because of pressure variations other than the photoacoustic effect of the samples.
As a result of our persevering research, the present inventors have invented a flow type photoacoustic detector that has enabled highly accurate detection of the photoacoustic output from a liquid sample which is not in a stationary state or sealed state, but in a flowing state.
The flow type photoacoustic detector here described comprises a sample cell; a light source for irradiating the sample in the sample cell, and detecting means for detecting pressure variations in the sample, characteri~ed in that the liquid inlet and outlet are spaced from each other along the axis of irradiation of the sample cell, and light window plates are arranged at each end of the cell.
More partlcularly in accordance with the invention there 1~ provided, a flow type photoacoustic detector for liquids comprising:
a sample cell having a flow line formed therein by spaced upper and lower surfaces, side portions and end portions, at least one of said end por-tions constituting an incldent light window plate;
a liquld inlet hole formed in said sample cell at one end of said flow line and an outlet hole formed in said cell at the other end of said flow line whereby liquid under pressure may flow therethrough;
a source of incident light arranged to irradia~e said flow llne through said window plate; and a piezoelectric detector positioned in said cell to be in acoustic cor.tact with liquid passing through said cell to measure the optical sound generated therein in the following sta~e.
Specific embodiments of the invention will now be described with reference to the accompanying drawings in which:
Fig~ 1 is a schematic outline view of the optical system in the detector;
Fig. 2 A~ B, C, D and E are enlarged sectional views of the flow cell;
Fig. 3 is a diagram in which variations in the signal and noise - 2a -magnitudes and the signal to noise ratio (S/N ratio) are plotted against modulation frequencies of an photoacoustic filter type modulator;
Fig. 4 shows the comparative chromatograms showing the results of concurrent measurements by the photoacoustic detector and an absorption detector commonly used in high-performance liquid chromatography; and Figo 5 shows the comparative diagrams obtained in case th~ background noise of the absorption detector is approximated to that of the photoacoustic detector.
Reference is now made to the accompanying drawings for illustrating a preferred embodiment of the present invention.
Fig~ 1 shows the general outllne of the optical system used in the new detector.
~ `he detector consists mainly of a light source 1 and a flow cell 4 containin~ sensor means. The incident light from the source l irradiates the ~iquid in the flow cell 4 under examination and the photoaGoustic output thus produced is sensed by sensor means mounted in the flow cell 4.
Although laser light is most preferred as the light source employed, emission lines from mercury lamps or light from xenon lamps may also be used, and both visible and ultraviolet radiation may be used as laser light.
As the sensors, pressure sensors SUCIl as Piezo~electric cera~ni~ and other piezo-electric sansors may be employed advantageously.
When the present ~eaching is applied to a liquid chromatographic detector, the volume of the flow cell within the detector should preferably be less than 300 ~ ~.
Although the presentdisclosure is not ]imited concerning the flow rate of the liquid in the cell, such flow rate should preferably be in the range of 0.1 m~/min to 10 m Q/min in case of liquid chromatographic detectors.
In case of monitoring devices, the flow cell capacity should preferably be less than 10 m ~ for the above flow rate. Fig. 2 A, B, C, D and E show different examples of the flow cell 4 in an enlarged sectional view respectively.
A flow line 21 in Fig. 2A is defined on upper and lower sides by a diaphragm 13 and a metallic block 19 respectively. Both end portions of the line 21 are clamp`edly secured by sealing metallic fixtures 20 and quartz window plates 14, 14' that are also used as incident light window plates, while the side portions thereof are clamped by suitable seals and metallic fixtures, not shown.
The line thus defined is placed on the path of the incident light.
The diaphragm 13 is bonded to the lower surface of a metallic block 18 having a through bore in which a piezoelectric ceramics element 12 îs accommodated and there bonded to the diaphragm 13. The element 12 is connected by a copper wire 10 to the foremost part of a connection terminal 8 connected in turn to the upper portion of the block 18. The element 12 is also secured to the termlnal 8 through a Teflon*tube 9 and a rubber seal 11. The metallic block 19 has two through holes opening on the side thereof facing the diaphrag,n 13, these holes connecting to an inlet 16 and an outlet 17 for the liquid sample under examination.
Reference is now made to Figs. 1 and 2 for illustrating the detection of photoacoustic output produced in the line from the liquid sample under examination.
The laser light from the source 1 has its frequency modulated to a desired frequency by a photoacoustic filter type modulator 2 fed by a generator 6 and condensed by lens 3. The light then passes through quartz window plate 14 as incident light so as to continuously irradiate the liquid flowing from the inlet 16 towards the outlet 17. The photoacoustic output thus produced in the cell is sensed by piezo-electric ceramic element 12 bonded to the * Trade Mark diaphragm 13 and is suitably recorded in recorder 7 foll~wing amplification by a lock-in amplifier 5. For using phase sensing ~nplifiers such as lock-in amplifier 5, suitable modulators need to be used for pulsed laser light or continuous incident light. Also, when the device is used in conjunction with a flowing liquid as in the case of high~performance liquid chromatography, it is desirable that any frequency may be chosen to cancel external noises caused by pump pulsations. It is also desirable that the liquid under examination by subjected to as small perturbational effects in the cell as possible and hence the diaphragm should preferably be made of gold or silver or other chemically stable material and have a smooth surface.
Detection of the photoacoustic output produced in the line from the liquid can be made not only by the arrangement shown in Fig. 2, but by suitably modified arrangements in which (b) the diaphragm 13 itself is designed as sensor Fig. 2 B, ~c) sensor means are accommodated in the line 21, Fig. 2 C, or (d) one or the other side of the liquid inlet 16 or the outlet 17 is deslgned as sensor Fig. 2 D, (e) the window plate 14' itself is designed as sensor Fig. 2 E.
The new detector may be advantageously employed, by using any one of the above configurations, for detecting the presence or concentrations of the solute in the flowing liquid under examination and especially as a detector for lLquid chromatography or other flow s~ate monitor.
Reference is made below to an embodiment as a `detector for liquid chromatography.
Fig. 3 shows the results of a test in which the detector is connected to a high performance liquid chromatographic system and the modulation frequencies of the incident light are varied. Thus, Fig. 3 shows the modulation frequencies on the abscissa and the changes in the magnitudes of signals and noises and the signal to noise ratio on the ordinate. It may be seen fron Fig. 3 that the 4V~
signal magnitude becomes ma~i~um at approximately 300 ~Iz, the noise level being then rather high, and that the signal to noise ratio (S/N ratio) becomes maximum in the neighborhood of S KHz. Thus it is ~pparent that external noises of various frequeDcies such as those caused by liquid delivery pumps may be produced in the course of flowing state measurement and that suitable means Eor selecting desired incident ligh~ frequencies may be cmployed for improving the detection sensitiv:ity.
Fig. 4 shows the results of a test in whlch the ~ ~LYe detector is comlected in series with a visible light absorption detector that is commonly employed as h:Lgh-performance liquid chromatographic detector and measurement was made by the two detectors concurrently for comparison. The measurement conditions were as listed below.
Liquid de1ivery pump, HLC-805 type pump for liquid chromatography, manufactured by TOYO SODA MANUFACTURING CO., LTD.
Column, stainless column, 4 mm inside diameter and 30.0 cm length packed with TSK-GEL LS 410 ODS SIL manufactured by TOYO SODA MANUFACTURING CO., LTD.
Sample A, 2-chlorodiethylaminoazobenzene B, 3-chlorodiethylaminoazobenzene C, 4-chlorodiethylaminoazobenzene Amount of sample in~ection, 3 mg each Visible light absorption detector Measuring wavelength, 488 nm Photoacoustic detector Measuring wavelength, 488 rm Modulation frequency, 4035 Hz Flow Rate, 1.0 m Q /min Eluent, methanol Fig. 4 shows that, with the photoacoustic detector, the signal to noise ratio (S/N ratio) may bc improved by a factor of lO as compared to the absorption cletector and thus the sensitivity may be improved by the same factor.
Fig. 5 shows the resu~t of a similar test in which the sample amount is reduced to one thirtieth (100 pg each) urlder otherwise the same conditions.
It may be seen from the chromatograms of Fig. 5 that, with setting of the detector sensitivity so that baseline noise levels of the two detectors are approximately the same, and witll in~ection of trace amounts (100 pg each) of the samples shown in Fig. 4, only small absorption peaks may be noticed with the absorption detector, whereas quantitative determinatlon of the sample may be possible with the photoacoustic detector.
Whereas the pieæo-electr$c element is arranged so as to contac~ the outside of the foildiaphragm13 in the example of Fig. 2A above stated, the element is embedded in seal 15 which forms the upper side of the line 21 in an example of Fig. 2B. Likewise, said element can be set, projecting in the line 21 as in Fig. 2C, the element can be arranged in the liq~lid inlet 16 as in Fig. 2D, or the element can be set in place of window plate ll!' as shown in Fig. 2E.
Detailed Description of the Invention This invention relates to a detector for measuring the photoacoustic output generated by a liquid sample which is irradiated by light. The liquid sample may be flowing through a cell while being irradiated. The invention also relates to a detector in which the liquid sample is allowed to flow through a flow cell equipped with pressure sensing means.
In this apparatus, intense light such as a laser beam irradiates the liquid sample in flowing state and the photoacoustic output generated by the liqu~d sample is measured to indicate the solute components in the liquid sample, without destroying the solute components and with high sensitivity. In general, a material, which has absorbed light, emits fluorescent light or exhibits a photoacoustic response, as shown in the following schema:
fluorescent absorption light _~
light ~ material sample - _ photoacoustic output Among these three processes, the light absorption process and the fluorescent light emission process are utilized practically for detecting changes in a flowing liquid such as in a high-performance liquid chromatographic detector. The light absorption process is used in both ultra-violet or visible light absorption detectors and the fluorescent emission uses a fluorescent light detector. In the absorption process the ratio of absorbed light to amount of light not absorbed by a material sample is measured. However, in the fluorescent light process or photoacoustic process the background light is approximately zero when the material sample does not emit fluorescent light or photoacoustic output, and thus it may be expected that highly sensitive measurement can be obtained compared to a material sample capable of emitting fluorescent light or photoacoustic output. In Eact, fluorescent light detectors are available for measuring fluorescent materials with high accuracy, but there ~Y~
~86~)Z
is a problem in that the number of fluorescen~ materials is limited.
It is therefore expected that photo-acoustic measurement can be applied to many materials with high accuracy for example for in case liquid chromatography etc., if the photoacoustlc measurement can be carried out while the materials are flowing. Such photoacoustic detection may be used either singly or in combination with fluorescence measurements. So far, the method of the photo-acoustic de~ection has been applied to many gas samples and solid samples, using condenser microphones as a sensor.
However, this method can not be applied to volatile materials, and 18 moreover water vapor is harmful to condenser microphones. This method has heretofore been applied to only a small number of liquid samples. In addition, no report has been made of using the photoacoustic detection for flowing liquid samples as encountered in high-performance liquid chromatography, because of pressure variations other than the photoacoustic effect of the samples.
As a result of our persevering research, the present inventors have invented a flow type photoacoustic detector that has enabled highly accurate detection of the photoacoustic output from a liquid sample which is not in a stationary state or sealed state, but in a flowing state.
The flow type photoacoustic detector here described comprises a sample cell; a light source for irradiating the sample in the sample cell, and detecting means for detecting pressure variations in the sample, characteri~ed in that the liquid inlet and outlet are spaced from each other along the axis of irradiation of the sample cell, and light window plates are arranged at each end of the cell.
More partlcularly in accordance with the invention there 1~ provided, a flow type photoacoustic detector for liquids comprising:
a sample cell having a flow line formed therein by spaced upper and lower surfaces, side portions and end portions, at least one of said end por-tions constituting an incldent light window plate;
a liquld inlet hole formed in said sample cell at one end of said flow line and an outlet hole formed in said cell at the other end of said flow line whereby liquid under pressure may flow therethrough;
a source of incident light arranged to irradia~e said flow llne through said window plate; and a piezoelectric detector positioned in said cell to be in acoustic cor.tact with liquid passing through said cell to measure the optical sound generated therein in the following sta~e.
Specific embodiments of the invention will now be described with reference to the accompanying drawings in which:
Fig~ 1 is a schematic outline view of the optical system in the detector;
Fig. 2 A~ B, C, D and E are enlarged sectional views of the flow cell;
Fig. 3 is a diagram in which variations in the signal and noise - 2a -magnitudes and the signal to noise ratio (S/N ratio) are plotted against modulation frequencies of an photoacoustic filter type modulator;
Fig. 4 shows the comparative chromatograms showing the results of concurrent measurements by the photoacoustic detector and an absorption detector commonly used in high-performance liquid chromatography; and Figo 5 shows the comparative diagrams obtained in case th~ background noise of the absorption detector is approximated to that of the photoacoustic detector.
Reference is now made to the accompanying drawings for illustrating a preferred embodiment of the present invention.
Fig~ 1 shows the general outllne of the optical system used in the new detector.
~ `he detector consists mainly of a light source 1 and a flow cell 4 containin~ sensor means. The incident light from the source l irradiates the ~iquid in the flow cell 4 under examination and the photoaGoustic output thus produced is sensed by sensor means mounted in the flow cell 4.
Although laser light is most preferred as the light source employed, emission lines from mercury lamps or light from xenon lamps may also be used, and both visible and ultraviolet radiation may be used as laser light.
As the sensors, pressure sensors SUCIl as Piezo~electric cera~ni~ and other piezo-electric sansors may be employed advantageously.
When the present ~eaching is applied to a liquid chromatographic detector, the volume of the flow cell within the detector should preferably be less than 300 ~ ~.
Although the presentdisclosure is not ]imited concerning the flow rate of the liquid in the cell, such flow rate should preferably be in the range of 0.1 m~/min to 10 m Q/min in case of liquid chromatographic detectors.
In case of monitoring devices, the flow cell capacity should preferably be less than 10 m ~ for the above flow rate. Fig. 2 A, B, C, D and E show different examples of the flow cell 4 in an enlarged sectional view respectively.
A flow line 21 in Fig. 2A is defined on upper and lower sides by a diaphragm 13 and a metallic block 19 respectively. Both end portions of the line 21 are clamp`edly secured by sealing metallic fixtures 20 and quartz window plates 14, 14' that are also used as incident light window plates, while the side portions thereof are clamped by suitable seals and metallic fixtures, not shown.
The line thus defined is placed on the path of the incident light.
The diaphragm 13 is bonded to the lower surface of a metallic block 18 having a through bore in which a piezoelectric ceramics element 12 îs accommodated and there bonded to the diaphragm 13. The element 12 is connected by a copper wire 10 to the foremost part of a connection terminal 8 connected in turn to the upper portion of the block 18. The element 12 is also secured to the termlnal 8 through a Teflon*tube 9 and a rubber seal 11. The metallic block 19 has two through holes opening on the side thereof facing the diaphrag,n 13, these holes connecting to an inlet 16 and an outlet 17 for the liquid sample under examination.
Reference is now made to Figs. 1 and 2 for illustrating the detection of photoacoustic output produced in the line from the liquid sample under examination.
The laser light from the source 1 has its frequency modulated to a desired frequency by a photoacoustic filter type modulator 2 fed by a generator 6 and condensed by lens 3. The light then passes through quartz window plate 14 as incident light so as to continuously irradiate the liquid flowing from the inlet 16 towards the outlet 17. The photoacoustic output thus produced in the cell is sensed by piezo-electric ceramic element 12 bonded to the * Trade Mark diaphragm 13 and is suitably recorded in recorder 7 foll~wing amplification by a lock-in amplifier 5. For using phase sensing ~nplifiers such as lock-in amplifier 5, suitable modulators need to be used for pulsed laser light or continuous incident light. Also, when the device is used in conjunction with a flowing liquid as in the case of high~performance liquid chromatography, it is desirable that any frequency may be chosen to cancel external noises caused by pump pulsations. It is also desirable that the liquid under examination by subjected to as small perturbational effects in the cell as possible and hence the diaphragm should preferably be made of gold or silver or other chemically stable material and have a smooth surface.
Detection of the photoacoustic output produced in the line from the liquid can be made not only by the arrangement shown in Fig. 2, but by suitably modified arrangements in which (b) the diaphragm 13 itself is designed as sensor Fig. 2 B, ~c) sensor means are accommodated in the line 21, Fig. 2 C, or (d) one or the other side of the liquid inlet 16 or the outlet 17 is deslgned as sensor Fig. 2 D, (e) the window plate 14' itself is designed as sensor Fig. 2 E.
The new detector may be advantageously employed, by using any one of the above configurations, for detecting the presence or concentrations of the solute in the flowing liquid under examination and especially as a detector for lLquid chromatography or other flow s~ate monitor.
Reference is made below to an embodiment as a `detector for liquid chromatography.
Fig. 3 shows the results of a test in which the detector is connected to a high performance liquid chromatographic system and the modulation frequencies of the incident light are varied. Thus, Fig. 3 shows the modulation frequencies on the abscissa and the changes in the magnitudes of signals and noises and the signal to noise ratio on the ordinate. It may be seen fron Fig. 3 that the 4V~
signal magnitude becomes ma~i~um at approximately 300 ~Iz, the noise level being then rather high, and that the signal to noise ratio (S/N ratio) becomes maximum in the neighborhood of S KHz. Thus it is ~pparent that external noises of various frequeDcies such as those caused by liquid delivery pumps may be produced in the course of flowing state measurement and that suitable means Eor selecting desired incident ligh~ frequencies may be cmployed for improving the detection sensitiv:ity.
Fig. 4 shows the results of a test in whlch the ~ ~LYe detector is comlected in series with a visible light absorption detector that is commonly employed as h:Lgh-performance liquid chromatographic detector and measurement was made by the two detectors concurrently for comparison. The measurement conditions were as listed below.
Liquid de1ivery pump, HLC-805 type pump for liquid chromatography, manufactured by TOYO SODA MANUFACTURING CO., LTD.
Column, stainless column, 4 mm inside diameter and 30.0 cm length packed with TSK-GEL LS 410 ODS SIL manufactured by TOYO SODA MANUFACTURING CO., LTD.
Sample A, 2-chlorodiethylaminoazobenzene B, 3-chlorodiethylaminoazobenzene C, 4-chlorodiethylaminoazobenzene Amount of sample in~ection, 3 mg each Visible light absorption detector Measuring wavelength, 488 nm Photoacoustic detector Measuring wavelength, 488 rm Modulation frequency, 4035 Hz Flow Rate, 1.0 m Q /min Eluent, methanol Fig. 4 shows that, with the photoacoustic detector, the signal to noise ratio (S/N ratio) may bc improved by a factor of lO as compared to the absorption cletector and thus the sensitivity may be improved by the same factor.
Fig. 5 shows the resu~t of a similar test in which the sample amount is reduced to one thirtieth (100 pg each) urlder otherwise the same conditions.
It may be seen from the chromatograms of Fig. 5 that, with setting of the detector sensitivity so that baseline noise levels of the two detectors are approximately the same, and witll in~ection of trace amounts (100 pg each) of the samples shown in Fig. 4, only small absorption peaks may be noticed with the absorption detector, whereas quantitative determinatlon of the sample may be possible with the photoacoustic detector.
Whereas the pieæo-electr$c element is arranged so as to contac~ the outside of the foildiaphragm13 in the example of Fig. 2A above stated, the element is embedded in seal 15 which forms the upper side of the line 21 in an example of Fig. 2B. Likewise, said element can be set, projecting in the line 21 as in Fig. 2C, the element can be arranged in the liq~lid inlet 16 as in Fig. 2D, or the element can be set in place of window plate ll!' as shown in Fig. 2E.
Claims (10)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A flow type photoacoustic detector for liquids comprising:
a sample cell having a flow line formed therein by spaced upper and lower surfaces, side portions and end portions, at least one of said end portions constituting an incident light window plate;
a liquid inlet hole formed in said sample cell at one end of said flow line and an outlet hole formed in said cell at the other end of said flow line whereby liquid under pressure may flow therethrough;
a source of incident light arranged to irradiate said flow line through said window plate; and a piezoelectric detector positioned in said cell to be in acoustic contact with liquid passing through said cell to measure the optical sound generated therein in the flowing state.
a sample cell having a flow line formed therein by spaced upper and lower surfaces, side portions and end portions, at least one of said end portions constituting an incident light window plate;
a liquid inlet hole formed in said sample cell at one end of said flow line and an outlet hole formed in said cell at the other end of said flow line whereby liquid under pressure may flow therethrough;
a source of incident light arranged to irradiate said flow line through said window plate; and a piezoelectric detector positioned in said cell to be in acoustic contact with liquid passing through said cell to measure the optical sound generated therein in the flowing state.
2. A flow type photoacoustic detector as claimed in Claim 1, wherein said inlet and outlet holes enter said sample cell at right angles to the length of said flow line.
3. A flow type photoacoustic detector as claimed in Claim 1, wherein the length of said flow line is substantially greater than the diameter of said inlet and outlet holes.
4. A flow type photoacoustic detector as claimed in Claim 1, wherein said source of light is a laser beam.
5. A flow type photoacoustic detector as claimed in Claim 1, further comprising a modulator for varying the intensity of said source of light.
6. A flow type photoacoustic detector as claimed in Claim 1, wherein said flow line upper surface comprises a diaphragm and said piezoelectric detector is bonded to said diaphragm.
7. A flow type photoacoustic detector as claimed in Claim 1, wherein said piezoelectric detector is positioned to be in direct contact with said liquid in said flow line.
8. A non-resonant flow type photoacoustic detector for liquids comprising:
a sample cell having a flow line with a capacity of less than 300 microliters formed therein by spaced upper and lower surfaces, side portions and end portions, at least one of said end portions constituting an incident light window plate:
a liquid inlet hole formed in said sample cell at one end of said flow line and an outlet hole formed in said cell at the other end of said flow line whereby liquid under pressure may flow therethrough; a source of incident light arranged to irradiate said flow line through said window plate; and a piezoelectric detector positioned in said cell to be in acoustic contact with liquid passing through said cell to measure the optical sound generated therein in the flowing state.
a sample cell having a flow line with a capacity of less than 300 microliters formed therein by spaced upper and lower surfaces, side portions and end portions, at least one of said end portions constituting an incident light window plate:
a liquid inlet hole formed in said sample cell at one end of said flow line and an outlet hole formed in said cell at the other end of said flow line whereby liquid under pressure may flow therethrough; a source of incident light arranged to irradiate said flow line through said window plate; and a piezoelectric detector positioned in said cell to be in acoustic contact with liquid passing through said cell to measure the optical sound generated therein in the flowing state.
9. A non-resonant flow-type photoacoustic detector as claimed in claim 8 wherein said end portions comprise quartz window plates clampedly secured to members forming said upper and lower surfaces by metallic fixtures, wherein said lower surface is formed by metallic block member, and said upper surface is formed by a diaphragm member having one side in direct contact with said liquid under pressure and its other side bonded to said piezoelectric detector.
10. A non-resonant flow-type photoacoustic detector as claimed in claim 9 wherein said input and output holes comprise two holes formed in opposite sides of said metallic block member.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55140031A JPS5764145A (en) | 1980-10-07 | 1980-10-07 | Flow type optoacoustic detector |
| JP140031/81 | 1980-10-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1186402A true CA1186402A (en) | 1985-04-30 |
Family
ID=15259340
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000387513A Expired CA1186402A (en) | 1980-10-07 | 1981-10-07 | Flow type photoacoustic detector |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5764145A (en) |
| CA (1) | CA1186402A (en) |
| DE (1) | DE3139917A1 (en) |
| FR (1) | FR2491623B1 (en) |
| GB (1) | GB2089041B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103822877A (en) * | 2014-02-27 | 2014-05-28 | 同济大学 | Portable nonlinear photoacoustic imaging system and photoacoustic imaging method |
| US9157311B2 (en) | 2010-07-08 | 2015-10-13 | Halliburton Energy Services, Inc. | Method and system of determining constituent components of a fluid sample |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5946839A (en) * | 1982-09-10 | 1984-03-16 | Hitachi Ltd | Photocoustic analysis device |
| JPS61102541A (en) * | 1984-10-25 | 1986-05-21 | Hitachi Ltd | Method and instrument for analyzing impurity in liquid |
| US4622845A (en) * | 1985-03-21 | 1986-11-18 | Westinghouse Electric Corp. | Method and apparatus for the detection and measurement of gases |
| JPS6224129A (en) * | 1985-07-24 | 1987-02-02 | Hitachi Ltd | Concentration analysis method and apparatus |
| DE3707622A1 (en) * | 1987-03-10 | 1988-09-22 | Pierburg Gmbh | Method and device for measuring low gas concentrations |
| US5125749A (en) * | 1990-09-24 | 1992-06-30 | The Dow Chemical Company | Probe for photoacoustic analysis |
| DE4225395A1 (en) * | 1992-07-29 | 1994-02-03 | Johannisthaler Forschungstechn | Appts. for photo-acoustive spectroscopy - has sample chamber and light source for periodical sample radiation together with pressuure sensor |
| CH685889A5 (en) * | 1994-09-07 | 1995-10-31 | Scr Crevoiserat S A | Method and apparatus for determining gas concentrations in a gas mixture |
| US5900533A (en) * | 1995-08-03 | 1999-05-04 | Trw Inc. | System and method for isotope ratio analysis and gas detection by photoacoustics |
| DE19602048C2 (en) * | 1996-01-20 | 1999-07-01 | Karlsruhe Forschzent | Pressure wave sensor |
| DE19744500A1 (en) * | 1997-10-09 | 1999-04-15 | Abb Research Ltd | Photoacoustic free-fall measuring cell |
| FR2775344B1 (en) * | 1998-02-20 | 2000-05-12 | Compucal | DEVICE FOR MEASURING MOLECULAR CONCENTRATION WITHOUT INTRUSION IN PRODUCTS SUCH AS FRUITS AND VEGETABLES |
| DE10012395B4 (en) | 2000-03-15 | 2010-04-29 | Abb Research Ltd. | Flowmeter |
| JP5525808B2 (en) * | 2009-12-25 | 2014-06-18 | 株式会社堀場製作所 | Magnetic pressure oxygen analyzer |
| WO2015097255A2 (en) * | 2013-12-23 | 2015-07-02 | Eric Chevalier | A versatile vascular access device |
| CN109283255B (en) * | 2018-08-06 | 2020-05-22 | 浙江大学 | Detection method of conveying flow pattern in pneumatic conveying process |
| EP3859307A1 (en) | 2020-01-28 | 2021-08-04 | Infineon Technologies AG | Light emitting structure, photo-acoustic spectroscopy sensing device, method for operating a photo-acoustic spectroscopy sensing device and apparatus for obtaining an information about a target gas |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3836950A (en) * | 1970-03-05 | 1974-09-17 | Trw Inc | Acousto-optical multi-constituent flow monitoring method and apparatus |
| US3646313A (en) * | 1970-04-08 | 1972-02-29 | Gilford Instr Labor Inc | Temperature controlled flow cell |
| US3762197A (en) * | 1970-09-14 | 1973-10-02 | Phillips Petroleum Co | Acoustical detecting apparatus |
| US3820901A (en) * | 1973-03-06 | 1974-06-28 | Bell Telephone Labor Inc | Measurement of concentrations of components of a gaseous mixture |
| US3948345A (en) * | 1973-06-15 | 1976-04-06 | Allan Rosencwaig | Methods and means for analyzing substances |
| JPS5459188A (en) * | 1977-10-19 | 1979-05-12 | Nec Corp | Infrared spectrophotometer apparatus of gas chromatography |
| US4200399A (en) * | 1978-11-20 | 1980-04-29 | General Motors Corporation | Resonant optoacoustic spectroscopy apparatus |
-
1980
- 1980-10-07 JP JP55140031A patent/JPS5764145A/en active Granted
-
1981
- 1981-10-07 CA CA000387513A patent/CA1186402A/en not_active Expired
- 1981-10-07 DE DE19813139917 patent/DE3139917A1/en active Granted
- 1981-10-07 FR FR8118854A patent/FR2491623B1/en not_active Expired
- 1981-10-07 GB GB8130315A patent/GB2089041B/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9157311B2 (en) | 2010-07-08 | 2015-10-13 | Halliburton Energy Services, Inc. | Method and system of determining constituent components of a fluid sample |
| CN103822877A (en) * | 2014-02-27 | 2014-05-28 | 同济大学 | Portable nonlinear photoacoustic imaging system and photoacoustic imaging method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5764145A (en) | 1982-04-19 |
| FR2491623A1 (en) | 1982-04-09 |
| JPH0219894B2 (en) | 1990-05-07 |
| GB2089041B (en) | 1984-05-31 |
| DE3139917A1 (en) | 1982-06-24 |
| GB2089041A (en) | 1982-06-16 |
| DE3139917C2 (en) | 1989-05-24 |
| FR2491623B1 (en) | 1985-06-28 |
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