OPTICAL PROBE FOR FLUORESCENCE ANALYSIS IN AQUEOUS MEDIA OF ORGANIC MOLECULES CONTAINING AT LEAST ONE FLUOROPHORE AND METHOD OF IMPLEMENTATION

Abstract

The invention relates to an optical probe for characterizing in situ and in real time the nature and concentration of fluorophores present in an aqueous medium. The probe comprises: - An assembly (2) of at least two different UV / visible light emission sources (20, 21, 2n) arranged to direct light into the aqueous medium, said sources being associated with first selection means (3); - An assembly (4) of at least two different first bandpass filters (40, 41, 4n), associated with second selection means (5) arranged to receive fluorescence emissions emitted by the fluorophores present in the aqueous medium; - A detector (6) of filtered fluorescence emissions transmitted by the assembly of first filters (40, 41, 4n); and - A central unit (7) designed to control the first and second selection means and to determine the concentration of the fluorophores. Figure for the abstract: Fig. 1

Description

Title of the invention: OPTICAL PROBE FOR FLUORESCENCE ANALYSIS IN AQUEOUS MEDIA OF ORGANIC MOLECULES CONTAINING AT LEAST ONE FLUOROPHORE AND METHOD OF IMPLEMENTATION

[0001] The present invention belongs to the technical field of analysis of organic molecules in aqueous media.

[0002] This analysis is particularly useful for characterizing the organic matter present in aquatic environments, wastewater treatment plants and drinking water treatment plants.

[0003] Indeed, organic matter is involved in a large number of biogeochemical processes.

[0004] Thus, in the field of water treatment, if organic matter is present in excessive quantities, it can be difficult to eliminate. This can then lead to the formation of carcinogenic disinfection by-products or to bacterial regrowth in the pipes that carry treated water to consumers, with adverse consequences for their health.

[0005] In the field of wastewater treatment, the objective is the removal of organic matter through various purification processes. However, knowledge of the quantity and nature of the organic matter present can enable the optimization of purification processes and thus, savings in energy and reagents.

[0006] Some physico-chemical parameters of water are very frequently used to characterize the organic matter present in solution in an aqueous medium: chemical oxygen demand (COD), biochemical oxygen demand at 5 days (BOD5) and dissolved organic carbon concentration (DOC).

[0007] Several analytical methods for determining these parameters are known.

[0008] BOD5, COD, and COD are determined by standardized conventional laboratory analytical methods. These methods require sample collection, possibly filtration, and then the analysis itself. The analysis takes from a few tens of minutes to 5 days. For example, the French standard ISO 5815-1:2019 can be cited for the measurement of BOD5, and the French standard ISO 6060:1989 for the measurement of COD.

[0009] However, they require spot sampling, the analysis of which then takes several hours, or even several days.

[0010] Measurement devices are also known that allow the in situ and real-time detection of certain fluorophores in an aqueous medium. However, their use may be limited to a single fluorophore, whereas knowledge of a large number of fluorophores is necessary to determine the relevant analytical parameters.

[0011] Moreover, these different devices are often designed to detect the same fluorophores, a maximum of 3 or 4, so that repeating measurements with several different devices does not allow access to a larger number of fluorophores.

[0012] The objective of the invention is to provide an improved device for characterizing, in situ and in real time, the nature and concentration of organic matter present in a given aqueous environment, and in particular for identifying different families of organic molecules (e.g., proteins, humic substances, etc.). This will optimize the removal of organic matter while limiting the use of energy and reagents, whether in wastewater treatment or water purification.

[0013] The invention relates to an optical probe intended to be, in use, at least partially immersed in an aqueous medium comprising organic molecules having at least one fluorophore, comprising: - A set of n UV / visible light emission sources at different wavelengths, n being an integer greater than or equal to 2, said sources being arranged to direct light outwards from the probe and into the aqueous medium when the probe is in use, said sources being associated with first selection means, - A set of m different first bandpass filters, m being an integer greater than or equal to 2, associated with second selection means arranged to receive fluorescence emissions emitted by said at least one fluorophore present in the aqueous medium in response to light excitation from one of said light emission sources; - A detector of filtered fluorescence emissions transmitted by the first set of m filters and - A central unit designed to control the first and second selection means and to determine the concentration of said at least one fluorophore, from the filtered and detected fluorescence emissions.

[0014] This probe can be placed directly in an aqueous environment to be analyzed, whether it is a continental aquatic environment (river, lake, groundwater for example), a marine aquatic environment or in wastewater treatment or drinking water plants, as soon as it is necessary to quantify organic matter by distinguishing different families of organic matter.

[0015] More specifically, the following may be cited: - a separate and combined wastewater collection network - wastewater treatment - monitoring the quality of receiving environments (rivers, bodies of water, marine environment) - monitoring of hydrocarbons in the marine environment - monitoring of wastewater discharges into receiving environments - Water treatment (drinking water production processes, groundwater, water supply network) - the agri-food sector - any industrial production process including products / reagents exhibiting fluorescence properties.

[0016] This probe implements the principle of fluorescence, which allows for analyses with very high sensitivity. It is based on the following principle: when an organic molecule containing one or more fluorophore groups (groups of atoms capable of re-emitting light when they receive excitation light, hereinafter referred to for simplicity as fluorophores) absorbs a photon with a wavelength between 275 and 600 nm corresponding to one of these fluorophores, it re-emits a photon with a longer wavelength between 300 and 700 nm. The intensity of the fluorescence can be directly proportional to the concentration of the fluorophore.

[0017] Thus, each fluorophore can be associated with a pair of parameters (excitation wavelength / fluorescence emission wavelength).

[0018] This probe alone allows the analysis of at least 10 different fluorophores and, preferably, of several dozen different fluorophores, for example 20, 30, 40 or more, and therefore the analysis of several families of organic molecules, with high sensitivity, which makes it possible to better characterize dissolved organic matter and to determine with high reliability in particular three parameters classically studied (COD, BOD5 and COD).

[0019] It has, in fact, been shown in the laboratory that the analysis of samples by fluorescence spectroscopy could provide indicators correlated in a statistically significant way with the values ​​of these three parameters, measured by reference methods (Thesis “Potential of use of 3D spectrofluorimetry for the online characterization of dissolved organic matter: from the wastewater treatment plant to the receiving environment. Environmental Engineering”, Angélique Goffin. University Paris-Est, 2017. French).

[0020] The probe therefore avoids the acquisition and manipulation of several different conventional devices and, moreover, allows obtaining much more information than These devices, which are inherently limited to the detection of only a few different fluorophores, would not allow it.

[0021] Furthermore, the analyses performed by the probe are easily adapted to the aqueous medium involved and the fluorophores being sought, thanks to appropriate programming of the central unit. The several dozen fluorophores that can be measured considerably increase the search spectrum of this probe. Moreover, this analysis is carried out in situ, in real time, and without the use of reagents.

[0022] The probe also has the advantage of being compact, easily transportable and therefore easy for a user to handle.

[0023] In advantageous embodiments, one and / or moreover, one and / or the other of the following provisions are also used: • The probe may comprise a first module and a second module connected to each other by electrical and optical connection means, the first module grouping together all the light emission sources, the first selection means and optical collection means designed to collect fluorescence emissions emitted by the aqueous medium in response to light excitation from one of said light emission sources and transmit them to the second module by optical connection means, and the second module grouping together all the first bandpass filters, the second selection means, the detector and the central unit, the first module being intended, in use, to be immersed in the aqueous medium. Thanks to this two-module design, the probe is more robust, with the most fragile parts placed in a module that can remain outside the aqueous environment and immobile. • The probe may include an amplifier associated with the detector. • The detector can be placed in the second module, between the filter assembly and the central unit, as can the possible amplifier. • A second bandpass filter can be placed downstream of each of the n light emission sources. • Focusing means can be provided upstream of optical collection means. • The second means of selection may consist of a filter wheel. • The central unit may include a microprocessor, a control device and memory. • The probe may include a device for monitoring the drift of the operation of the light emission sources and the detector equipped with the possible amplifier. • The probe may include a housing, a portion of which forms a window that is transparent to allow the passage of light emitted by the sources and fluorescence emissions emitted by said at least one fluorophore, in use, in the UV / visible range. • The probe may include a cleaning system associated with the porthole. • The device for controlling the drift in the operation of the light emission sources may include a reflective blade. • The reflective blade can be associated with the cleaning system.

[0024] The invention also relates to a method for measuring at least one fluorophore in an aqueous medium comprising organic molecules having at least one fluorophore, the method comprising the following steps: - The selection of a light emission source from a set of n light emission sources at different wavelengths, in the range 250-600 nm, n being an integer greater than or equal to 2; - The emission of light through said aqueous medium from the selected source; - The selection of a bandpass filter from a set of m first filters, m being an integer greater than or equal to 2; - The filtration and detection of fluorescence emissions emitted by the aqueous medium in response to light excitation from said selected source; - The processing of filtered and detected fluorescence emissions in order to determine the concentration of said at least one fluorophore.

[0025] In advantageous implementation modes, one and / or more of the following provisions are also used: • Filtration of fluorescence emissions can be carried out before their detection. • Filtered fluorescence emissions can pass through an amplifier before being detected and processed.

[0026] The invention will be better understood and other objects, advantages and features thereof will become more apparent from the following description of embodiments given by way of non-limiting examples and which is made with reference to the accompanying drawings in which:

[0027] [Fig. 1], a schematic view illustrating a first embodiment of the probe according to the invention,

[0028] [Fig.2], a schematic view illustrating a preferred embodiment of the probe according to the invention, in two modules,

[0029] [Fig.3], a partial schematic view illustrating one of the modules of [Fig.2], with a cleaning system in the retracted position and an inactive drift control device,

[0030] [Fig.4], a schematic perspective view illustrating the cleaning system in the retracted position of [Fig.3] and the drift control device inactive,

[0031] [Fig. 5], a partial schematic view illustrating one of the modules of [Fig. 2], with an active drift control device and

[0032] [Fig.6], a schematic perspective view illustrating the active drift control device.

[0033] The elements common to the figures will be designated by the same references.

[0034] Fig. 1 illustrates a probe 1 according to the invention, made in a single module.

[0035] It comprises a housing 10, for example of parallelepiped shape, one face of which has a transparent window or porthole 11 and through which the selected source can emit photons in the UV / visible range towards the outside of the housing, into the aqueous medium 8.

[0036] Inside this housing, there is provided a set 2 of n (n greater than or equal to 2) UV / visible light emission sources and, preferably, at least four sources which emit at different wavelengths located in the range 250-600 nm, or in the range 250-400 nm or even in the range 250-365 nm.

[0037] Of course, this does not preclude assembly 2 from comprising at least two sources emitting UV / visible light at the same wavelength. It may, in fact, be necessary to operate several sources emitting at the same wavelength simultaneously to increase the sensitivity of the probe.

[0038] Fig. 1 illustrates three sources 20, 21, 2n which can be, for example, light-emitting diodes (or LEDs) and emit at the following wavelengths: 275 nm, 310 nm, 365 nm.

[0039] This housing also includes first selection means 3, connected to the assembly 2 and by means of which one of these sources is selected, depending on the fluorophore that one wishes to analyze in the aqueous medium.

[0040] The housing comprises a set of 4 different first bandpass filters (m greater than or equal to 2) connected to second selection means 5 by means of which a given filter can be chosen, again depending on the fluorophore to be analyzed. The wavelengths corresponding to each filter are typically between 300 and 700 nm.

[0041] This set of first m bandpass filters is arranged to receive fluorescence emissions emitted by fluorophores present in the aqueous medium in response to light excitation from one of said light emission sources. In other words, the first m bandpass filters are downstream of the medium and receive the emission radiation from the fluorophores present in the medium.

[0042] Each first filter has a wavelength range that extends by plus or minus 10 mm around the central wavelength of the filter where the transmittance is highest.

[0043] This assembly may in particular take the form of a filter wheel 40, 41, 4n, for example marketed by the company Edmund Optics.

[0044] The invention is of course not limited to this embodiment and it could also be envisaged to make this assembly in the form of a juxtaposition of static filters and a rotating mirror capable of selectively directing the fluorescence emissions from the aquatic environment towards one or another static filter.

[0045] Alternatively, this assembly could also be made in the form of a filter rack combined with an arm capable of directing one of the filters of the rack through the fluorescence emissions from the aquatic environment and of storing the filter at the end of the measurement.

[0046] In general, this assembly comprises at least two different bandpass filters, i.e. allowing photons of different wavelengths to pass through, and preferably at least twelve different filters.

[0047] A fluorescence emission detector 6 and a central unit 7 are also provided in the housing 1.

[0048] The detector 6 is located between the set 4 of filters and the central unit 7 and receives the filtered fluorescence emissions transmitted by the first set of m filters.

[0049] The latter includes, for example, a microprocessor 70, a control device 71 and a memory 72, the device 71 and the memory 72 being controlled by the microprocessor 70.

[0050] An amplifier (not shown in [Fig. 1]) may be provided between the filter set 4 and the detector 6.

[0051] As illustrated in [Fig.1], the first and second selection means 3, 5 are connected to the control device 71 which controls them.

[0052] The set 4 of filters and the first and second selection means 3, 5 are connected to a power supply (not illustrated in [Fig.1]) which is controlled by the central unit 7.

[0053] Preferably, downstream of each source 20,21,2n, and upstream of the window 11, i.e. between these sources and the window, a second bandpass filter 50 is provided. Each of these second filters 50 downstream of a source therefore receives the excitation radiation from that source and allows the width of the excitation line to be limited.

[0054] This probe is at least partially immersed in the aqueous medium 8, in which various organic molecules 80 are found in dissolved form, so that the window is totally immersed in the aqueous medium 8.

[0055] The operation of this probe, in a given aqueous medium, is as follows:

[0056] Depending on the fluorophore to be analyzed in the medium 8, the microprocessor 70 of the central unit 7 controls, via the control device 71, the first selection means 3 to select the light source 20-2l-2n emitting at the desired wavelength and the second selection means 5 to select the appropriate bandpass filter 40-41-4n.

[0057] The selected light emission source, for example source 20, then emits light through the aqueous medium 8, preferably filtered by a bandpass filter. The light excitation from this source is represented schematically by arrow FL

[0058] The fluorophore to be analyzed, which is present in the aqueous medium 8, emits fluorescence towards the housing in response to light excitation from the selected source 20. The fluorescence emissions, originating from the medium 8 and passing through the window 10, are schematically represented by arrow F2. These emissions are in the UV / visible range.

[0059] The photons emitted by fluorescence are, in the first instance, filtered by the filter of the assembly 4 which has been selected, then detected and converted into an electrical signal by the detector 6. This detection consists of measuring the number of photons received at the selected wavelength and transforming it into a corresponding electrical signal, possibly amplified.

[0060] Thus, the photons emitted by fluorescence are filtered, detected and converted into an electrical signal, which will then be processed by the central unit 7 and, more particularly, by the microprocessor 70 to which the detector 6 is connected.

[0061] This processing, performed by the microprocessor, makes it possible to determine the fluorescence intensity associated with a fluorophore (for example, tyrosine) or a family of fluorophores (for example, humic acids) present in medium 8, based on the signal provided by the detector and generated according to the number of photons. This intensity is correlated with the concentration of the fluorophore or the family of fluorophores. For simplicity, we will henceforth refer only to fluorophores.

[0062] This information can be stored in memory 72. It can also be transmitted by the microprocessor 70 to a display device for the probe user. This transmission is shown schematically by arrow F3.

[0063] It is therefore understood that, thanks to the plurality of light sources and filters present in the probe, it is also capable of detecting a plurality of different fluorophores. Thus, the same probe can be used for all these fluorophores. Before a measurement, it is simply a matter of selecting the light source and the filter adapted to the detection of a given fluorophore, using the central unit 7. This selection can, for example, be made by the user via a touchscreen equipped with buttons, each of which corresponds to a fluorophore.

[0064] For example, if the probe has four light emission sources and twelve bandpass filters, it allows the analysis of 48 different fluorophores, with the same probe, and in a contained volume.

[0065] This constitutes a considerable advantage compared to known probes.

[0066] Indeed, the probe according to the invention makes it possible to analyze a very large number of fluorophores, and to select among them the most relevant fluorophores according to the measurement site and, more generally, the intended application.

[0067] The probe according to the invention is therefore very versatile and suitable for a very large number of operational conditions.

[0068] However, if necessary, its design makes it easy to adapt the probe to very specific analytical conditions. Indeed, if the fluorophores measurable by the probe are not suitable for the application, it is very easy to modify the filters of the filter wheel, particularly when the latter is, in a preferred embodiment, in an exposed module. Thus, modifying the filters does not require any realignment of the probe's optics, resulting in a probe perfectly suited to the intended application.

[0069] It appears that the filter assembly placed on a motorized assembly 4, the detector 6 and / or the amplifier are fragile electronic parts which can be damaged when the housing is used, due to potential vibrations and shocks.

[0070] Figure 2 illustrates a probe according to the invention designed to overcome this drawback.

[0071] This probe 100 is made up of two separate modules connected electrically and optically to each other: a first module 1a intended to be immersed in the aqueous medium to be analyzed and a second module 1b intended to remain on the surface and comprising the most fragile elements.

[0072] Each of these modules comprises a housing 10a, respectively 10b, for example of parallelepiped shape. The housing 10a has a face with a window or porthole transparent to UV / visible radiation.

[0073] Thus, the first module la comprises a set 2a of n (n greater than or equal to 2) UV light emission sources 20a,21a,2na and preferably at least four sources which emit at different wavelengths in the range 250-600 nm or in the range 275-365 nm.

[0074] It includes first selection means 3a, linked to the set 2a, which allow the selection of one of these sources.

[0075] This first module also includes optical collection means 9 which may optionally include focusing means 90. The latter are located upstream of the collection means 9, that is to say before them on the path of the fluorescence emissions.

[0076] The second module 1b includes a set 4b of m different first bandpass filters (m greater than or equal to 2), connected to second selection means 5b by means of which a given filter can be chosen, again depending on the fluorophore that one wishes to analyze.

[0077] The number n of UV light emission sources and the first number m of bandpass filters are chosen such that the combination of the n sources and the m filters allows the measurement of at least 10 different fluorophores, preferably at least 20 different fluorophores, advantageously at least 30 different fluorophores, typically at least 40 different fluorophores.

[0078] The wavelengths corresponding to each first filter are again typically between 300 and 700 nm.

[0079] This assembly 4b can notably take the form of a filter wheel 40b, 41b, 4nb, but it can take other forms, as explained previously, as long as it is possible to reversibly select the filter through which the fluorescence emissions are to be passed.

[0080] In general, this assembly comprises at least two different first bandpass filters and, preferably, at least twelve filters.

[0081] The second module 1b includes a fluorescence emission detector 6b and a central unit 7b.

[0082] The detector 6b is located between the set 4b of first m filters and the central unit 7b.

[0083] Preferably, an amplifier 60b is provided between assembly 4b and detector 6b. This amplifier increases the sensitivity of the probe and therefore the accuracy of the measurements. Of course, such an amplifier could also be provided in the probe illustrated in [Fig. 1].

[0084] In practice, the detector 6b and the amplifier 60b are grouped into a single device which is a photomultiplier.

[0085] The central unit comprises a microprocessor 70b, a control device 71b and a memory 72b, the device 71b and the memory 72b being controlled by the microprocessor 70b, programmed appropriately.

[0086] As illustrated in [Fig.2], the first and second selection means 3a and 5b are connected to the control device 71b which controls them.

[0087] Furthermore, the assembly 4b and the first and second selection means 3a and 5b are connected to an electrical power supply 73b which is controlled by the central unit 7b.

[0088] In other words, as in [Fig.1], the central unit 7b supplies electricity to the various components of the probe according to the invention that require it, and controls their operation.

[0089] An optical link 91 is also provided between the optical collection means 9 and the filter assembly 4b. These collection means serve to collect and inject the fluorescence-emitted photons into the link 91. This function can also be performed directly with the optical link. This link takes, for example, the form of an optical fiber whose length is adapted to the application. This allows the first module to be placed in the aquatic environment and the second module to be placed at a sufficient distance to protect the components and, if necessary, facilitate the transmission of results and / or the calibration of the probe.

[0090] The operation of this probe 100 is similar to that which has been described for probe 1, with the difference that only the first module la is immersed in the aqueous medium 8 studied.

[0091] The central unit 7b controls, via the control device 71b, the first selection means 3a to select the light source emitting at the desired wavelength and the second selection means 5b to select the appropriate bandpass filter, depending on the fluorophore to be analyzed.

[0092] The selected light emission source, for example source 20a, then emits light through the window 1la, towards the aqueous medium 8. The light excitation from this source is represented schematically by arrow FL

[0093] The fluorophore to be analyzed, which is present in the aqueous medium 8, emits fluorescence towards the housing in response to light excitation from the selected source 20a. The fluorescence emissions, originating from the medium 8 and passing through the window 1a, are schematically represented by arrow F2.

[0094] They are, initially, collected in the first module la, by the collection means 9. It is understood that the presence of focusing means 90 allows to optimize the collection of fluorescence emissions from the medium 8.

[0095] The photons emitted by fluorescence are transmitted by the optical link 91 to the filter of the assembly 4b which has been selected, which filters them and then transmits them to the detector 6b.

[0096] Preferably, these filtered photons are amplified by the amplifier 60b before being transmitted to the detector 6b which detects them and converts them into an electrical signal.

[0097] This signal is then processed by the central unit 7b and, more particularly, by the microprocessor 70b to which the detector 6b is connected.

[0098] This processing carried out by the microprocessor makes it possible to determine the concentration of the fluorophore in question which is present in the medium 8, from a fluorescence intensity.

[0099] This information can be stored in memory 72b. It can also be transmitted by the microprocessor 70b to a display device for the probe user. This transmission is shown schematically by arrow F3.

[0100] It is therefore understood that this probe 100 has the advantages of the probe 1 illustrated in [Fig.1], while being more robust, the most fragile parts of the probe being placed in a module which can remain outside the aqueous environment and, moreover, immobile.

[0101] This design allows the use of a photomultiplier, which therefore has the additional advantage of increasing the sensitivity of the probe, without risking damage to the photomultiplier.

[0102] It was thus observed that the sensitivity of this probe allows the detection of much lower concentrations than that which conventional probes allow.

[0103] Some examples of detection sensitivity will now be given: - Tyrosine (measured at 275 nm / 304 nm): 1 pg.L 1 - Tryptophan (measured at 275 nm / 375 nm): 0.1 pg.L - Humic acids (measured at 365 nm / 436 nm): 0.1 mg C.L 1

[0104] Fig. 2 also illustrates a cleaning system 12a of the porthole 1 la which will be described in more detail with regard to figures 3 to 6 which only illustrate the first module la.

[0105] This cleaning system allows the porthole to be cleaned regularly to prevent the formation of biofilm on it and therefore contributes to the proper functioning of the probe.

[0106] As illustrated in [Fig. 4], this cleaning system 12a can take the form of a windshield wiper 120a located outside the first module la and capable of being actuated by a motor 121a located inside the first module la. The windshield wiper is connected to the motor 121a by a shaft 122a, this shaft driving the windshield wiper in rotation when the motor is running, so as to perform a back-and-forth movement on the window.

[0107] The cleaning system 12a is shown in the retracted position in Figures 3 and 4, with the motor then stopped.

[0108] Figures 3 and 4 show that the first housing also includes a reflective blade 13a which is advantageously mounted on the axis 122a.

[0109] This blade will allow control and correction of the drift over time of the operation of the emission sources in the UV / visible range 20a,21a, 2na as well as of the detector 6b and the possible amplifier 60b.

[0110] In the retracted position of the cleaning system 12a, the blade 13a is in an inactive position, i.e. it is not in the path of the photons emitted by the light source towards the aqueous medium 8.

[0111] Reference is now made to Figures 5 and 6, which illustrate blade 13a in the active position. In this position, blade 13a is in the path of the photons emitted by the light source towards the aqueous medium 8, so that it can intercept the light emitted by one of the sources of set 2a.

[0112] It is understood that, in the illustrated embodiment, the blade 13a is placed in this active position by the motor which drives the windshield wiper 120a as well as the blade 13a. When the blade is fixed to the windshield wiper, as in the illustrated embodiment, the central unit is programmed to allow the motor to stop in the active position of the blade, so that the windshield wiper remains stationary until the drift measurement has been carried out.

[0113] The control of the drift of the operation of a UV / visible light emission source for example the source 20a, as well as of the detector 6b and the possible amplifier 60b is carried out as follows: the source 20a is selected by the central unit by means of the first selection means 3a.

[0114] This source 20a then emits photons at a known theoretical wavelength, the photons are reflected by the reflecting plate 13a towards the collection means 9.

[0115] The central unit 7 then commands the second selection means 5b to select the drift control filter, which is placed on the filter wheel between the reflecting plate and the detector. This is a high optical density filter (OD 6) that therefore allows less than one millionth of the incident photon flux to pass through. A hole with a diameter on the order of a millimeter has been drilled in its center using a point, in order to allow light to pass through unobstructed. This is therefore a spatial filtering.

[0116] The photons collected by the collection means 9 are transmitted via the optical link 91 to the selected drift control filter, which filters them and transmits them to the detector 6b, via the optional amplifier 60b.

[0117] The electrical signal from the detector is processed by the central unit 7b, which compares the power of this signal to the nominal power of the source 20a, which it knows. This processing therefore makes it possible to determine whether the source 20a is indeed emitting photons at its nominal power.

[0118] If the probe according to the invention includes a bandpass filter downstream of each of the n light emission sources and upstream of the window 1a, and if the source 20a malfunctions such that the emitted wavelength differs from the theoretical emission wavelength of the source, then, during the measurement, the detector 6b will receive no signal or a weakened signal. The central unit will therefore be able to deduce that the source 20a is not functioning correctly and will alert the user for maintenance purposes.

[0119] Thus, this drift control device makes it possible to monitor the evolution of the measured signal over time and to very easily identify a slippage or malfunction of the photon emission sources, the detector and / or The amplifier, since it can be activated while the probe is being used in an aqueous environment. Furthermore, this control is performed remotely, in situ, without having to physically intervene on the module.

[0120] Indeed, the fluorescence of the aqueous medium is negligible compared to the reflection of light by the slide. This is why the device is effective even if the probe is placed in an aqueous medium.

[0121] The check can be done on demand or systematically, during each cleaning programmed by the central unit.

[0122] If defects are found, an exchange of parts can be carried out when the operation is erratic, or a recalibration of the calculations can be carried out when the drift is precisely known and it evolves slowly but constantly (until the final replacement of the components concerned, of course).

[0123] The invention is not, however, limited to this embodiment. Thus, the transition of the blade from its inactive position to its active position, and vice versa, could also be controlled by the central unit, independently of the cleaning of the porthole.

[0124] Of course, a cleaning system and a drift control device can also be provided in the probe 1 illustrated in [Fig. 1].

[0125] In addition, the cleaning system and the drift control device can be independent of each other.

Claims

1. Demands An optical probe intended to be, in use, at least partially immersed in an aqueous medium (8) comprising organic molecules having at least one fluorophore, comprising: - An array (2, 2a) of n sources (20, 21, 2n; 20a, 21a, 2na) of UV / visible light emission at different wavelengths, n being an integer greater than or equal to 2, said sources being arranged to direct light outwards from the probe and into the aqueous medium when the probe is in use, said sources being associated with first selection means (3, 3a), - An array (4, 4a) of m different first bandpass filters (40, 41, 4n; 40b, 41b, 4nb), m being an integer greater than or equal to 2, associated with second selection means (5, 5b) arranged to receive fluorescence emissions emitted by said at least one fluorophore present in the aqueous medium in response to light excitation from one of said light emission sources;- A detector (6, 6b) of filtered fluorescence emissions transmitted by the set of first m filters (40, 41, 4n; 40b, 41b, 4nb) and - A central unit (7, 7b) designed to control the first and second selection means and to determine the concentration of said at least one fluorophore, from the filtered and detected fluorescence emissions, characterized in that the probe comprises a first module (1a) and a second module (1b) connected to each other by electrical (73b) and optical (91) connection means, the first module (1a) grouping the set (2a) of light emission sources, the first selection means (3a) and optical collection means (9) designed to collect fluorescence emissions emitted by the aqueous medium in response to light excitation from one of said light emission sources and transmit them to the second module (1b) by the optical connection means (91),and the second module (1b) comprising the set (4b) of bandpass filters, the second selection means (5b), the detector (6b) and the central unit (7b), the first module being intended, in use, to be immersed in the aqueous medium.

2. Probe according to claim 1, comprising an amplifier associated with the detector (6, 6b).

3. Probe according to claim 2, wherein the detector is placed in the second module (1b), between the filter assembly (4b) and the central unit (7b), as the optional amplifier.

4. Probe according to any one of claims 1 to 3, wherein a second bandpass filter (50) is placed downstream of each of the n light emission sources.

5. Probe according to any one of claims 1 to 4, wherein focusing means (90) are provided upstream of optical collection means.

6. Probe according to any one of claims 1 to 5, wherein the second selection means (4, 4b) consist of a filter wheel.

7. Probe according to any one of claims 1 to 6, wherein the central unit (7, 7b) comprises a microprocessor (70, 70b), a control device (71, 71b) and a memory (72, 72b).

8. Probe according to any one of claims 1 to 7 comprising a device for controlling the drift of the operation of the light emission sources, the detector and the optional amplifier.

9. Probe according to any one of claims 1 to 8 comprising a housing (1, la) of which a portion (11,11b) forming a window is transparent for the passage of light emitted by the sources and fluorescence emissions emitted by said at least one fluorophore, in use, in the UV / visible range.

10. Probe according to claim 9 comprising a cleaning system associated with said porthole.

11. Probe according to any one of claims 8 to 10, wherein the device for controlling the drift of the operation of the light emission sources comprises a reflective blade (13a).

12. Probe according to claim 11, wherein the reflective blade (13a) is associated with the cleaning system.

13. A method for measuring the concentration of at least one fluorophore in an aqueous medium (8) comprising organic molecules having at least one fluorophore, the method using the probe according to any one of claims 1 to 12 and comprising the following steps: - The selection of a light emission source from the set (2,2a) of n light emission sources at different wavelengths, in the range 250-600 nm; - The emission of light through said aqueous medium from the selected source; - The selection of a bandpass filter from the set of the first m filters; - The filtration and detection of the fluorescence emissions emitted by the aqueous medium in response to the light excitation from said selected source; - The processing of the filtered and detected fluorescence emissions in order to determine the concentration of said at least one fluorophore.

14. A method according to claim 13, wherein the filtration of fluorescence emissions is carried out before their detection.

15. A method according to claim 13 or 14, wherein the filtered fluorescence emissions pass through an amplifier before being detected and processed.

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