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
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/416—Systems
  • G01N27/447—Systems using electrophoresis
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
• • 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
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
  • G01N21/6486—Measuring fluorescence of biological material, e.g. DNA, RNA, cells

Definitions

• the present invention aims to provide an alternative and relatively simple method of capture, detection, identification and quantification of the components contained in the air.
• components in the broad sense is understood to mean all the particles in suspension in the air, spores, odoriferous molecules, volatile organic compounds, better known under the acronym of VOC.
• the invention combines a method of sampling components, a method for handling and capturing components removed, an optical method for detecting the presence of these components based on the principle of the emission of a fluorescence signal. induced by a laser emitting in deep UV ( ⁇ 300nm), and a capillary electrophoresis type separation analysis method that allows the identification and quantification of components.
• this deposit was formed by the deposition of the components contained in the air.
• the observation of this phenomenon made it possible to observe that the rate of formation of this deposit was mainly related to the size of the analysis duct (section and length), to the material used for the analysis duct, to the flow rate of the air flow used to physically ensure the sampling, and the thermal conditions surrounding said analysis conduit.
• the air to be analyzed is circulated for a given time in a small diameter analysis duct by lowering the temperature of the air at the inlet of the analysis duct, so as to cause a condensation of the moisture contained in the air on the internal walls of the analysis duct causing the deposition of the components on said internal walls,
• a capillary tube type analysis duct having an internal diameter of less than 700 ⁇ is used.
• the temperature is lowered by creating a vacuum at the outlet of the capillary analysis tube so as to cause adiabatic expansion of the air entering the capillary tube.
• the air is cooled at the inlet of the analysis duct with the aid of refrigeration means arranged around the outer wall of said analysis duct.
• the spectral response obtained during the passage of the scraping liquid front in the detector cell is analyzed to determine the presence of traces of components within said detector. forehead.
• the air contained in said volume of air so as to define the evolution over time of the spectral responses caused by the traces of components.
• the same detector can also be used to perform the native fluorescence analysis and capillary electrophoresis.
• the invention also relates to a device for analyzing traces of components present in the air comprising
• a fluorescence detector comprising a laser emitting in the deep UV a driving beam of a flow of material flowing in an analysis duct formed of a transparent material, an optical device for targeting this excitation, and a detector of light allowing the collection of the fluorescence emitted by said material flow
• circulation means adapted to pass successively a liquid fluid and a gaseous fluid in the analysis duct from an inlet to an outlet.
• This device is characterized in that cooling means are arranged at the input of the analysis duct.
• the circulation means are formed by a suction pump capable of creating a vacuum at the outlet of the analysis duct, and whose flow rate is adjusted to create an adiabatic expansion at the inlet of said duct. analysis capable of cooling the air entering the analysis duct.
• the analysis device can also provide that means make it possible to direct the inlet of the analysis duct alternately to the volume of air that is to be analyzed, to a bottle containing a scraping liquid, to a bottle containing a buffer liquid or to a receptacle in which has been collected a volume of liquid containing the components to be analyzed.
• the analysis duct is a capillary tube whose diameter is less than 700 ⁇ .
• the analysis device is a device which comprises an elliptical cavity of revolution, arranged so that the beam and the analysis duct pass through the optical device by means of passages arranged in said optical device, the axis of the laser beam and the axis of the analysis duct both being centered on one of the focal points of the optical device, both being orthogonal to the axis of revolution of the optical device and making an angle of less than 90 ° between them, of such that the excitation point of the material flow flowing in the analysis duct corresponds to the focal point of the cavity and the collection of the light emitted or transmitted by the flow of material flowing in the analysis duct through an opening conveniently disposed near the second focal point of the optical cavity can be performed outside the device.
• FIG. 1 represents a schematic view of the deposition phenomenon of the components at the inlet of the analysis duct
• FIG. 2 represents a schematic view of the capture of the deposit in the front of the scraping liquid
• FIGS. 3 to 8 schematically illustrate the main steps of the method according to the invention
• FIG. 9 is a diagram representing the signal emitted successively by the water and the air used for cleaning the capillary tube
• FIG. 10 is a diagram representing the signal emitted by the passage of the reference air followed by the passage of the air to be analyzed (here gasoline vapor)
• Figure 11 represents the fluorescence intensity at a given wavelength emitted by the passage of a front under the native fluorescence detector
• FIG. 12 represents the spectral images formed by the passage of a front under the native fluorescence detector, and carried out at regular time intervals
• the sampling of the component C particle sample proposed by the invention is based on the principle of a cooling of the air circulating at the inlet E of the analysis duct 1 to favor the deposit D of components contained in a gaseous flow circulating in the analysis duct.
• the device therefore comprises an analysis duct 1, a first end of which forms the inlet E of the capillary tube, and which can be brought into a chamber 2 containing air to be analyzed, as shown in FIG. Figure 5, or to be immersed in a vial containing a gas or a liquid, as shown in Figures 3, 4 or 6 to 8.
• the formation of the deposit is related to the size of the internal surface, and the Air cooling is related to the extent of adiabatic relaxation, and therefore to the aspirated volume.
• Air cooling is related to the extent of adiabatic relaxation, and therefore to the aspirated volume.
• capillary tubes are also proposed in very varied internal-external diameters, and the length is left to the initiative of the developer of the device.
• these tubes are delivered covered with a protective material that provides them with sufficient flexibility to be handled without special precautions.
• the choice could be a silica capillary tube of 375 ⁇ of external diameter. These are provided by way of example with internal diameters ranging from 20 pm to 700 pm. The results presented in the context of the present description were obtained using a capillary tube 75 ⁇ in diameter. This diameter is also the one that is best suited to perform the electrophoretic separation as will be seen later.
• the "suction" function is provided by a pump 3 placed at the outlet of the analysis duct and which creates a depression capable of generating a stream of air within the analysis duct whose flow can vary from 0.001 ⁇ / h at 150 ml / min.
• the flow rate of the pump will be sufficient to achieve the largest adiabatic relaxation possible at the inlet of the capillary tube.
• a pump type "syringe" can meet most of the observed configurations.
• the cooling of the air at the inlet of the capillary tube can also be obtained using more conventional means such as for example a refrigeration means formed of a coil surrounding the inlet of the capillary tube in which a liquid or a gas is circulated at low temperature, or a Peltier effect type means.
• the cooling capacity will be adapted accordingly, observing that the lower the temperature is important more the desired condensation effect at the inlet of the capillary tube is effective, and shorter will be the time required to obtain the amount of particle deposition useful for carrying out the analysis.
• a further lowering of the temperature of the air sucked in at the inlet of the capillary tube by about ten degrees Celsius makes it possible to halve the time necessary for the formation of a sufficient deposit D. Collection of internal deposits of the analysis conduit.
• the viscosity of the liquid is suitably selected, it is observed that the liquid inlet front in the analysis duct 1 plays the role of a piston; as it penetrates into the analysis duct, the components C are torn off the wall (this is the expected function of cleaning). And it was found, as is illustrated in FIG. 2 shows that these components C remain concentrated in the front edge F of the cleaning liquid without dispersing in the liquid designated hereinafter as scraping liquid R.
• the method according to the invention relies advantageously on this observation.
• this viscosity may be much lower for a capillary tube.
• a capillary tube 75 ⁇ m in internal diameter, water, alcohol, sodium hydroxide, hydrochloric acid, can be used without problem.
• the surface tension of the scraping liquid R becomes preponderant compared to the effects related to the viscosity, and it is this first property which ensures the desired piston effect.
• a first application consists in detecting the presence of components in the front F.
• a device emitting in the deep UV (whose wavelength is less than 300 nm) is preferably chosen. At these excitation wavelengths, it is indeed possible to induce a so-called native fluorescence signal.
• the optical device 5, used in the embodiment of the invention therefore uses the principle of detection based on native fluorescence. It is proposed to advantageously use the optical device described in patent FR 2 869 686, which is not only compatible with the use of a capillary tube, but which is also compatible with the excitation wavelength of a laser emitting in deep UV at a wavelength of 224 nm.
• the optical device described in this patent is based on the use of a hollow reflecting elliptical cell.
• the capillary tube 1 previously prepared with a window (ablation a few millimeters of the protective layer so as to leave the silica capillary tube bare), is installed at a focus of the elliptical cell in such a way that it is orthogonal to its major axis, and that its window is centered on this same hearth.
• the incident laser beam illuminates the capillary tube 1 at this focus with an angle less than 90 °.
• the fluorescence signal emitted by the components C circulating in the capillary tube is emitted at this focus, and is collected at the second focal point of the elliptical cell.
• This device also has the advantage of being placed anywhere along the capillary tube. Those skilled in the art can therefore position it more or less far from the sample taking, depending on the characteristics it has retained to achieve the suction of air and to create the front containing the components C in the front F of the scraping liquid R. It also allows the capillary tube change without special precautions, which can prove useful when one seeks to optimize the performance of the device of measured
• the same syringe pump 3 which is used to create the deposit D on the inner walls of the capillary tube by adiabatic expansion will also be used to suck the scraping liquid R which will create on his forehead F circulation in the capillary tube 1 a kind of plug which will concentrate the components C contained in the deposit D.
• the syringe pump 3 and the sealed bottle 4 in the assembly described above.
• the presence of a fluorescence signal indicates the presence or absence of C components in the front F of the scraping liquid R.
• an optical device equipped a monochromator and a light detector for simultaneously detecting the entire light spectrum as a strip of detection diodes, or a CCD camera, of the type described in the publication FR 2 869 686 so as to detect the fluorescence emission spectrum of the components C contained in the front F and whose wavelengths can be between 280 nm and 2 ⁇ .
• the shape of this spectrum can give useful information on the nature of the components C contained in the front F.
• the depression is maintained in the capillary tube 1 and in the chamber 4 after the passage of the front F in the cell of the native fluorescence detector 5.
• the front of the scraping liquid then arrives at the end of the capillary tube without significant deformation.
• the nature of the forehead is preserved and does not vary in composition.
• the first drop G formed at the outlet of the capillary tube and as shown in FIG. 7, is recovered in the sealed reservoir 4 in order to analyze its contents.
• a receptacle 6 can be disposed in said sealed reservoir 4 so as to collect said first drop G of liquid.
• This receptacle can usefully be associated with homogenization means (not shown) capable of conditioning the fluid contained in said receptacle. 2
• a measurement technique suitable for small amounts of sample such as capillary electrophoresis whose interest is also to be automated relatively easily.
• identification means such as high pressure liquid chromatography, the implementation of which requires heavier means.
• the electrodes are disposed at both ends of the capillary tube as shown in FIG. 8.
• a first end of the capillary tube can be immersed alternately in the receptacle 6 containing the sample to be analyzed. and formed by the drop G from the front of the scraping liquid, and in a bottle containing a buffer liquid T. This function can be performed manually or by an automaton.
• the second end of the capillary tube is placed in a bottle for receiving the buffer liquid T at the outlet of the capillary tube.
• This bottle can itself be kept in depression by the pump 3.
• the voltage applied by the generator between the two ends of the capillary tube is between 20,000V and 30,000 V.
• the instrument also comprises the modules necessary for performing electrophoretic separation, such as a high voltage generator, a temperature regulation of the capillary tube, as well as the appropriate control and acquisition software.
• the capillary tube 1 is cleaned by means of a suitable cleaning liquid W.
• the end of the capillary tube is immersed in a vial 2 previously filled with said cleaning liquid W as illustrated in FIG. 4.
• This cleaning liquid may be water, a solution based on sodium hydroxide, a solution containing
• the suction function of the cleaning liquid is provided by the pump 3, and the cleaning liquid is recovered at the outlet of the capillary tube in the bottle 4.
• the native fluorescence detector 5 is used during this cleaning operation to check that the capillary tube has been properly cleaned.
• the cleaning time depends on the result given by the native fluorescence detector.
• a cleaning procedure may include successive aspirations of air and water.
• the cycle can be repeated as many times as necessary so as to check the stability and repeatability of the cleaning operation.
• the first end E of the capillary tube is disengaged from its bottle, to be positioned to collect the air to be analyzed as shown in Figure 5.
• the pump 3 is started for the time necessary to create a sufficient deposit D at the inlet E of the capillary tube this air creating adiabatic relaxation as described above.
• the native fluorescence detector is able to detect C components contained in the air.
• the level of detection is a function of the elements that are contained in the air, and the conditions in which the suction, the internal diameter of the capillary tube and the suction flow rate among others take place.
• the phenomenon of decay of the fluorescence signal corresponds to the creation of the adiabatic expansion at the inlet of the capillary tube. Indeed, the deposition of component at the inlet of the capillary tube has the effect of reducing the suction diameter. This diameter being reduced, adiabatic expansion increases, and the amount of air sucked decreases. It is therefore logical that the signal collected by the native fluorescence detector decreases. It should be noted that if the suction pump is maintained for a long time, the capillary tube becomes clogged.
• the first end of the capillary tube 1 is immersed in a bottle filled with the scraping liquid R, as shown in FIG. 6.
• the scraping liquid R is sucked by the depression formed in the sealed bottle 4 by the pump 3, and do it F stores the deposit D of C components deposited at the inlet E of the capillary tube 1.
• the front F flows to the window of the capillary tube placed under the native fluorescence detector 5 to ensure the detection of components C contained in the front, and then to the other end of the capillary tube, to be finally collected in the receptacle 6 for this function as shown in Figure 7 .
• the operating time will be adapted, so that the liquid flowing in the capillary tube reaches the plunging end in the receptacle 6 in which a drop G of liquid is collected.
• the native fluorescence detector 5 is used during this operation to identify the presence of components C in the front F of the scraping liquid R.
• the output signal of the native fluorescence detector for a wavelength of 310 nm is as shown in FIG. 11.
• the detection peak corresponds to the passage of the front F in which the components C are concentrated.
• the front F is identified by the native fluorescence detector 5
• This spectral analysis is obtained by replacing the photomultiplier tube with a CCD camera or a diode array, or by using a multiple photomultiplier tube component.
• the capillary tube 1 is then conditioned to ensure electrophoretic separation.
• the two ends of the capillary tube are immersed in bottles filled with buffer liquid T, a generic term for the liquid intended to ensure electrophoretic separation.
• the capillary tube 1 is filled with the buffer liquid by circulating the liquid inside the capillary tube.
• the pump 3 is used to ensure this conditioning.
• the receptacle 6 containing the front F of the scraping liquid collected in the preceding step and containing the components C to be analyzed is introduced, so as to introduce a sample S of the liquid to be analyzed. in the capillary tube, either by vacuum with the pump, or by an electric field generated by the high voltage generator.
• the end of the capillary tube is again immersed in the bottle filled with buffer liquid T, and the separation can begin under the action of the electric field generated by the generator.
• the voltage applied between the terminals is of the order of 30 000 V.
• the passage of the components C under the native fluorescence detector generates peaks, which make it possible to identify the components separated individually by comparing the time of appearance of this signal with the time of appearance obtained with a pure control component. It is also possible to quantify the components by measuring the areas of these same peaks by comparison with the reference signals previously obtained by measuring control samples containing a pure component.

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• 2010
  • 2010-11-02 FR FR1004323A patent/FR2966929B1/fr not_active Expired - Fee Related
• 2011
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