Benzodiazepine detection method and detection device

Abstract

Benzodiazepine Detection Method and Detection Device The invention relates to a method for detecting a benzodiazepine molecule in a liquid which uses an amperometric electrochemical sensor configured to emit a signal in the presence of the molecule. The invention also relates to the sensor and to a device provided with the electrochemical sensor and a container, such as a drinking glass. The invention finds particular application in the field of preventive security. Figure for abstract: Fig. 1

Description

Title of the invention: Benzodiazepine detection method and detection device Technical field

[0001] The invention relates to a method for detecting a benzodiazepine molecule in solution in a liquid, based on an electrochemical reaction which produces a specific electric current in the presence of the molecule.

[0002] The invention also relates to an electrochemical sensor configured to implement this method and emit a signal in the presence of the molecule.

[0003] Finally, the invention relates to a device for the detection in solution of benzodiazepines such as diazepam, clonazepam, bromazepam, loprazolam, oxazepam, nordazepam, lormetazepam, alprazolam, midazolam, clorazepate, clotiazepam, loflazepate, estazolam, lorazepam, nitrazepam, prazepam, temazepam, flunitrazepam and chlordiazepoxide. This device comprises the electrochemical sensor and can also be provided with a container in which the liquid is placed.

[0004] The invention finds application as a preventive security tool in the field of events. Prior art

[0005] There are methods for detecting and measuring benzodiazepines for medical analysis or forensic medicine purposes. These analysis methods allow the detection and measurement of certain benzodiazepines in bodily fluids such as urine and saliva. Electrochemical sensors in the case of benzodiazepines are also the most studied. However, to date there is no device for the immediate detection of benzodiazepines in a glass of drink.

[0006] For example, Elisa Lozano-Chaves M., Palacios-Santander JM, Cubillana-Aguilera LM, Naranjo-Rodnguez L, Hidalgo-Hidalgo-de-Cisneros JL, in the article “Modified carbon-paste electrodes as sensors for the determination of 1,4-benzodiazepines: Application to the determination of diazepam and oxazepam in biological fluids.”, Sens. Actuator B. Chem. 2006;115:575-583, developed a protocol for the detection of diazepam, oxazepam and temazepam in urine and blood plasma. In this method, it is necessary to prepare a buffer solution of the biological fluid to be analyzed, before starting the detection. The device works only by controlling the pH, the conductivity and the buffer, so the method is complex. It requires preparation of the liquid to be analyzed and cannot be implemented outside of a laboratory.

[0007] Nagappa N., Mimani T., Sheshadri B., Mayanna S., Mayanna G., in the article “Cyclic voltammetric studies of diazepam using glassy carbon electrode-estimation of diazepam in pharmaceutical samples”, Chem. Pharm. Bull. 1998;46:715-717, developed a similar method for the detection of diazepam in a buffered solution at pH=1. This protocol has the same drawbacks as the previous one.

[0008] Another method for detecting benzodiazepines in a commercial beverage has recently been proposed.

[0009] Mayra V. Paschoarelli, Mathias S. Kavai, Lucas F. de Lima and William R. de Araujo, in their article “Laser-scribing fabrication of a disposable electrochemical device for forensic detection of crime facilitating drugs in beverage samples, Volume 255, 1 April 2023, 124214, have successfully detected diazepam and midazolam with a polyetherimide (PEI)-graphene electrode. This method has many drawbacks: the device used is not reusable, the electrode is difficult to industrialize given its complexity, and the detection protocol only works in a basic medium. It is therefore not possible to detect the presence of a benzodiazepine in a glass of acidic drink, without having to neutralize the drink beforehand. In addition, the method only works on two specific molecules and does not allow the blind detection of other benzodiazepine molecules.Such constraints make it impossible to immediately detect a drug that has been poured into a person's glass without their knowledge.

[0010] There is therefore no device or electrical protocol allowing the immediate electrochemical detection of a benzodiazepine in a glass of drink. Furthermore, no existing method allows the presence of any type of benzodiazepine that would be present in solution to be detected. The methods of the prior art are only suitable for one or two molecules maximum.

[0011] The need therefore remains to propose an electrical protocol and an electrochemical sensor making it possible to detect the presence of all existing benzodiazepines in all existing commercial drinks. The need also remains to propose a device configured to implement a method for detecting benzodiazepines, which is industrializable, reusable, and allows very rapid detection without having to resort to preparation of the liquid to be analyzed or to an analysis laboratory. Statement of the invention

[0012] The invention meets this need by proposing a method for detecting a benzodiazepine molecule present in a liquid, said method consisting of: - bringing the liquid comprising the benzodiazepine molecule into contact with an amperometric electrochemical sensor comprising at least one working electrode Ew, a reference electrode Eref, a counter-electrode Ec, and a potentiostatic circuit connected to each of the electrodes, - supplying the potentiostatic circuit with a current source to subject the liquid to at least two sweeps B1 and B2 in linear potential over time, each sweep B1 and B2 being carried out between a potential value VI and a potential value V2, the value V2 being lower than the value VI and the speed of the sweep B1 being different from the speed of the sweep B2, - generating a signal to alert on the presence of a benzodiazepine when a current recorded during the sweeps B1 and B2 exceeds a threshold value during at least one of the two sweeps B1 and B2.

[0013] The present invention has numerous advantages.

[0014] The detection method is reversible in the presence of benzodiazepines in a liquid. It also allows the detection of all benzodiazepine molecules.

[0015] It can be implemented in a device comprising an electrochemical sensor and a glass of beverage comprising the liquid, without having to modify the pH of the liquid and without having to transfer the liquid into another container before recording the current during the potential scans. Beverages have highly variable chemical compositions, which depend on the solvent (water and / or alcohol), the pH and numerous additives which can impact the generated electrical signal. This is particularly the case for molecules with electrochemical activity such as ascorbic acid, taurine, citric acid, vitamins, caffeine and sucrose. Similarly, certain preservatives and certain flavorings can also undergo electrochemical reactions which may mask the detection of benzodiazepines. Finally, the carbon dioxide widely used in carbonated and sparkling drinks forms bubbles on the working electrode, which may distort the measurements.It is therefore very surprising that the pH, solvents and ingredients used in commercial beverage recipes do not impact the reliability of the method of the invention. Also, the method of the invention does not generate false positives, even in the case of a complex mixture of different molecules. The method works on a multitude of beverages, under different pH conditions.

[0016] In other words, the invention makes it possible to be selective for all benzodiazepine molecules in a complex and variable liquid medium.

[0017] Another object of the invention relates to an electrochemical sensor configured to implement the method described above.

[0018] Finally, the invention provides a device for detecting a benzodiazepine in a liquid comprising the electrochemical sensor and a container intended to contain the liquid.

[0019] The sensor and the device can advantageously be reused several times during of the implementation of the process, which is reversible. Brief description of the drawings

[0020] [Fig. 1] is a diagram of the two potential sweeps B1 and B2 according to the method for detecting a benzodiazepine of the invention between a potential value VI and a potential value V2, with a linear staircase potential of step E superimposed on a square wave of amplitude A and frequency fl and f2, respectively.

[0021] Figures 2A, 2B and 2C represent the low frequency and high frequency voltammograms from scans B1 and B2 obtained with Evian water, Evian water containing alprazolam and Evian water containing diazepam, without stirring the liquid during the measurement.

[0022] [Fig.3] represents the low frequency voltammogram from the B1 or B2 scan obtained with Evian water containing alprazolam, by stirring the liquid during the measurement.

[0023] Figures 4A, 4B and 4C represent the low frequency and high frequency voltammograms from scans B1 and B2 obtained with a vodka-Redbull® mixture, a vodka-Redbull® mixture containing alprazolam and a vodka-Redbull® mixture containing diazepam, without stirring the liquid during the measurement.

[0024] [Fig.5] represents the low frequency and high frequency voltammograms from the B1 and B2 scans obtained with a vodka-Redbull® mixture containing diazepam, by stirring the liquid during the measurement.

[0025] Figures 6A, 6B and 6C represent the low frequency and high frequency voltammograms from scans B1 and B2 obtained with rosé wine, rosé wine containing alprazolam and rosé wine containing diazepam, without stirring the liquid during the measurement. Description of the embodiments

[0026] A first object of the invention relates to a method for detecting a benzodiazepine molecule present in a liquid, said method consisting of: - bringing the liquid comprising the benzodiazepine molecule into contact with an amperometric electrochemical sensor comprising at least one working electrode Ew, one reference electrode Eref, one counter-electrode Ec, and a potentiostatic circuit connected to each of the electrodes, - supplying the potentiostatic circuit with a current source to subject the liquid to at least two sweeps B1 and B2 in linear potential over time, each sweep B1 and B2 being carried out between a potential value VI and a potential value V2, the value V2 being lower than the value VI and the speed of sweep B1 being different from the speed of sweep B2, - generate a signal to alert you to the presence of a benzodiazepine when a current recorded during scans B1 and B2 exceeds a threshold value during at least one of the two scans B1 and B2.

[0027] The threshold value is advantageously chosen to be representative of the presence of a benzodiazepine.

[0028] The method of the invention comprises a step of energizing the amperometric sensor by at least two potential sweeps. The variation in potential produces a base current, while an additional electric current is generated during the reduction of the benzodiazepine molecule(s), so that a peak in current intensity recorded at the working electrode occurs in the presence of the molecule in the liquid. Providing a signal transmitter which is triggered in the event of the appearance of the intensity peak makes it possible to detect the benzodiazepine.

[0029] The threshold value may correspond to at least one parameter of the current recorded at the working electrode, such as for example the presence of a current intensity peak, the intensity of a peak and / or the width of a peak. In a particular embodiment, the threshold value corresponds to an additional current intensity greater than IpA. The threshold value may comprise both the height of a current intensity peak and the width at the base of this peak. For example, the threshold value comprises a peak height greater than 1 pA and a peak width at the base greater than or equal to 15 mV.

[0030] The current is preferably recorded at regular time intervals throughout the duration of scans B1 and B2.

[0031] The speed of the scan B1 is preferably between 10 mV / s and 100 mV / s, for example between 15 mV / s and 50 mV / s or between 20 mV / s and 30 mV / s, and the speed of the scan B2 is preferably between 100 mV / s and 300 mV / s, for example between 150 mV / s and 250 mV / s or between 180 mV / s and 220 mV / s.

[0032] The method of the invention may comprise a series of alternating scans B1 and B2, the first scan of the series being able to be B1 or B2.

[0033] In a particular embodiment of the invention, the two potential sweeps B1 and B2 are linear staircase potential sweeps superimposed on periodic pulses. The pulses may be direct, or comprise a continuous alternation of direct pulses and inverse pulses.

[0034] In a particular embodiment of the invention, at least one of the two potential sweeps B1 and B2, preferably the two sweeps B1 and B2, each correspond to a linear staircase potential sweep of steps E1 and E2 respectively, superimposed on periodic pulses of amplitude A1 and A2 and of frequency f1 and f2 respectively. The sweep speed is modulated as a function of the value of the step and the value of the frequency.

[0035] The frequency fl of the pulses of the B1 scan and the frequency f2 of the pulses of the B2 scan are advantageously different and between 2 Hz and 50 Hz. The difference between fl and f2 may be at least 5 Hz. For example, the frequency fl of the pulses of the B1 scan is between 15 Hz and 50 Hz (so-called "high frequency" scan) and the frequency f2 of the pulses of the B2 scan is between 2 Hz and 15 Hz, preferably between 2 Hz and 10 Hz (so-called "low frequency" scan). In a particular embodiment, the frequency fl is between 15 Hz and 30 Hz and the frequency f2 is between 2 Hz and 5 Hz.

[0036] The inventors have found, very surprisingly, that carrying out at least two potential scans at different speeds, for example by imposing different voltage frequencies on the same linear potential range, makes it possible to optimize the detection of benzodiazepines, by broadening the detection field of molecules whose electrochemical properties vary. The method of the invention is adapted to the reduction kinetics of all benzodiazepines, which depends on the chemical formula of the molecule, but also on the nature of the liquid in which it is found. Carrying out a scan at low speed (for example with low-frequency pulses) makes it possible to detect molecules whose reduction is rather slow, while a scan at high speed (for example with high-frequency pulses) makes it possible to detect molecules whose reduction is faster.

[0037] The benzodiazepine molecule is in particular chosen from diazepam, clonazepam, bromazepam, loprazolam, oxazepam, nordazepam, lor-metazepam, alprazolam, midazolam, clorazepate, clotiazepam, loflazepate, estazolam, lorazepam, nitrazepam, prazepam, temazepam, flunitrazepam and chlordiazepoxide. The kinetics of reduction of the benzodiazepine depends on the structure of the molecule and the composition of the liquid. Also, when the oxidation-reduction reaction is rapid, a high speed (for example with high frequency pulses) will allow more efficient detection. Conversely, when the reaction is slower, a lower speed (e.g. with lower frequency pulses) will be sufficient for detection.

[0038] The amplitude A1 of the pulses during scanning B1 and / or the amplitude A2 of the pulses during scanning B2 are, for example, between 10 mV and 100 mV, between 20 mV and 80 mV, or between 40 mV and 70 mV, independently of one another. A person skilled in the art will know how to optimize the amplitude A to increase the selectivity of the method for detecting benzodiazepines compared to other molecules present in the liquid (water, oxygen, additives).

[0039] The pulses of the scan B1 may have a duration of between 50 ms and 300 ms, for example between 150 ms and 250 ms, and an amplitude A1 of between 50 ms and 200 mV, while the pulses of the scan B2 may have a duration of between 10 ms and 50 ms, for example between 20 ms and 30 ms, and an amplitude A2 of between between 50 mV and 200 mV.

[0040] As regards the step of the staircase potential, the value of the step E1 during scanning B1 and the value of the step E2 during scanning B2 are advantageously comprised - independently of one another - between 1 mV and 20 mV, preferably between 5 mV and 15 mV.

[0041] The parameters of the scanning potential allowing reliable detection of benzodiazepines are advantageously compatible with very rapid, even immediate, detection of the molecules.

[0042] In a particular embodiment of the detection method of the invention, at least one of the two potential sweeps B1 and B2, preferably each potential sweep B1 and B2, is a linear staircase potential sweep superimposed on a square wave comprising direct pulses and inverse pulses. The frequency f1 of the square wave of sweep B1 and the frequency f2 of the square wave of sweep B2 are of different values ​​and between 2 Hz and 50 Hz.

[0043] For example, each potential sweep B1 and B2 is a linear staircase potential sweep superimposed on a square wave comprising forward pulses and reverse pulses, the frequency f1 of the square wave of sweep B1 being between 15 Hz and 50 Hz, and the frequency f2 of the square wave of sweep B2 being between 2 Hz and 10 Hz. The current recorded during sweeps B1 and B2 may be equal to a differential current If-Ir, If being recorded at the end of each forward pulse and Ir being recorded at the end of each reverse pulse.In this embodiment, the amplitude Al of the pulses during scanning B1 and the amplitude A2 of the pulses during scanning B2 are advantageously between 10 mV and 100 mV, the pulses of scanning B1 may have a duration of between 50 ms and 300 ms, and an amplitude Al of between 50 mV and 200 mV, while the pulses of scanning B2 may have a duration of between 10 ms and 50 ms and an amplitude A2 of between 50 mV and 200 mV. The value of the step El during scanning B1 and the value of the step E2 during scanning B2 are advantageously between 5 mV and 15 mV.

[0044] The B1 scan and the B2 scan of this embodiment can be represented by the curve of [Fig.l] on which each scan starts at the value VI and ends at the value V2, the step of the step potential of the B1 scan and the step potential of the B2 scan being equal to E, the amplitude Al of the square Fonde of the B1 scan and the amplitude A2 of the square Fonde of the B2 scan being equal to A, the frequency fl of the square Fonde of the B1 scan and the frequency f2 of the square Fonde of the B2 scan being of different values. The current If is recorded at the end of each forward pulse while the current Ir is recorded at the end of each reverse pulse, the signal being generated when the differential current If-Ir exceeds a value threshold.

[0045] When the scan B1 and / or the scan B2 comprises only direct pulses, a current II is recorded just before each pulse and a current 12 is recorded just after each pulse, the signal making it possible to detect the presence of a benzodiazepine being generated when the differential current 12-11 exceeds a threshold value.

[0046] The method of the invention comprises at least two potential scans, including scan B1 and scan B2. The time interval between two scans can range from a few seconds to several minutes for optimized consumption.

[0047] The working electrode Ew is preferably a carbon electrode, for example graphite, glassy carbon or boron-doped diamond.

[0048] The working electrode Ew can be found in very varied shapes and dimensions: wire, disc, pin, thin layer deposited on another metal or charge collector. The surface area of ​​the working electrode Ew can be between 0.002 mm2 and 100 mm2

[0049] The material of the counter-electrode Ec is preferably a metal resistant to the conditions of use of a container comprising the electrodes, such as a drinking glass. In this case, it is preferred that the metal be resistant to detergent products and corrosive acidic drinks. The material of the counter-electrode Ec is preferably chosen from platinum, carbon or stainless steel. The surface area of ​​the counter-electrode Ec is preferably larger than that of the working electrode Ew.

[0050] A reference electrode Eref is subjected to a practically constant potential under the conditions of an electrochemical measurement and serves as a reference for determining the potential applied to the working electrode Ew. The reference electrode Eref can be AgIAgCl. However, the latter are difficult to implement for certain applications, due to their high cost, long-term stability problems observed with reusable drinking glasses, their fragility under usage conditions or their lack of dishwasher compatibility. The reference electrode Eref is therefore preferably a pseudo-reference electrode. For this, platinum offers good performance, like most metals in the platinoid family. The size of the electrode is not critical since it only serves as a reference.

[0051] The material of the reference electrode Eref preferably comprises platinum. The value of the potential V1 is preferably less than -0.3 V and the potential V2 is preferably greater than -1.5 V, when the reference electrode Er is made of platinum. For example, the potential varies from -0.6 V / Pt to -1.4 V / Pt during the scan B1 and during the scan B2. In one embodiment, the benzodiazepine molecule is detected upon the appearance of a differential current peak in a potential range between -0.75 V / Pt to -1.35 V / Pt.

[0052] In one embodiment of the method, false positives linked to movements of the liquid container can be limited, or even eliminated, by choosing a threshold value of the recorded current defined by a height of the current peak greater than IpA and a width of the current peak at its base greater than or equal to 15 mV.

[0053] The signal generated in the event of exceeding the current threshold may be a signal of a luminous, colored, audible, vibratory nature, or be a combination of these.

[0054] The liquid in which it is desired to detect the benzodiazepine and which comes into contact with the electrochemical sensor may be a liquid having a pH less than or equal to 7. Very advantageously, the liquid may have a pH between 2 and 4, which was not possible in the methods of the prior art requiring a basic liquid.

[0055] In a particular embodiment, the liquid is a beverage comprising water and / or alcohol. The liquid is in particular chosen from an energy drink, a mixture of alcoholic and non-alcoholic beverage(s), an alcoholic beverage and mineral water.

[0056] The liquid may therefore comprise at least one molecule chosen from a flavoring, a preservative, a sweetener, carbon dioxide, ascorbic acid, taurine, citric acid, caffeine and sucrose. Examples of drinks are fruit juices, colas, energy drinks based on caffeine or taurine, lemonades, wines (red, white, rosé, sparkling, crément, champagne), beers, strong alcohols (whiskey, vodka, gin, tequila), or cocktails based on strong alcohols and non-alcoholic drinks.

[0057] The administration of a benzodiazepine without the knowledge of a victim is carried out by adding the benzodiazepine to the glass of drink in solid powder form, or in liquid form after having previously dissolved it in a little water or alcohol. The dose necessary for an act of chemical submission depends on the benzodiazepine molecule, as well as the type of drink, alcohol being known to amplify its effects. It is accepted that the average dose necessary to obtain chemical submission is between 1 mg and 20 mg. It is for example 1 mg for alprazolam and 10 mg for diazepam 10 mg. The invention therefore finds application in the field of preventive security and makes it possible to combat criminal and tortious attempts at chemical submission. It is aimed in particular at the events sector and allows a drink consumer to be alerted to the introduction of a sedative in his glass.

[0058] The liquid comprising the benzodiazepine molecule can be taken from a container and then placed on the electrochemical sensor connected to a current source. Alternatively, the electrochemical sensor is placed in the container containing the liquid, so that the detection of the benzodiazepine can be carried out in real time, as soon as an individual adds the benzodiazepine to the glass of drink of a person at without his knowledge.

[0059] The detection method is effective regardless of the volume of liquid used, regardless of the concentration of the benzodiazepine molecule in the liquid and regardless of the temperature of the liquid. For example, detection is reliable for a liquid volume of 5 to 100 cl and a temperature ranging from 0°C to 25°C.

[0060] A second subject of the present invention relates to an amperometric electrochemical sensor configured to detect a benzodiazepine in a liquid comprising at least one working electrode Ew, a reference electrode Eref, a counter-electrode Ec, a potentiostatic circuit connected to each of the electrodes, and an alert unit configured to generate a signal, said potentiostatic circuit being configured to impose on the working electrode Ew at least two sweeps B1 and B2 in linear potential at different speeds, and the signal being generated when a current recorded during the sweeps B1 and B2 exceeds a threshold value representative of the presence of a benzodiazepine.

[0061] The characteristics which have been described in the context of the first subject of the invention may be common to the second subject of the invention, and will not be described again in this part.

[0062] When the value representative of the presence of a benzodiazepine is a threshold value of the intensity of the current recorded at the working electrode, the sensor may comprise a light-emitting diode emitting a light signal when it is crossed by a current whose intensity is greater than the threshold value. The threshold value is advantageously lower than the value of the current generated in the presence of a benzodiazepine in the liquid, and higher than the value of the current generated in the absence of a benzodiazepine in the liquid.

[0063] According to a particular embodiment of the invention, the sensor is intended to come into direct contact with a beverage. In this case, the materials constituting it are preferably non-toxic and compatible with hygiene and food safety standards. The sensor is advantageously resistant to usual conditions of use such as washing with dishwashing liquid or being put in a dishwasher. The materials are advantageously chosen to be resistant to degradation which would occur upon contact with the liquid. Finally, the sensor has the advantage of being relatively insensitive to the movements and displacements of the person carrying the glass of beverage. It is also preferred that the sensor be adapted to very variable volumes of liquid.

[0064] Finally, a third object of the present invention relates to a device for the detection of a benzodiazepine in a liquid, characterized in that it comprises i) an amperometric electrochemical sensor as described above, ii) a container intended to contain the liquid, and iii) an electrical power source for said sensor. electrochemical.

[0065] The characteristics relating to the first object and the second object of the invention which have been described previously may be common to the third object of the invention when they apply thereto. They will therefore not be described again in this part.

[0066] The device has the advantage of immediately detecting the presence of a benzodiazepine in any liquid, even when the liquid is subject to movement, such as movement of the container containing the liquid, or agitation of the liquid in the container.

[0067] The container may be a container such as a drinking glass or a plastic cup. Alternatively, the container may be a support on which the liquid is deposited before starting the detection method.

[0068] In a particular application, the electrochemical sensor is integral with the container, which makes it possible to avoid disassembly of the sensor, replacement of the sensor, or transfer of the liquid each time the device is used. The device is advantageously reusable and machine washable.

[0069] The invention is illustrated by the following examples, in which the temperature is between 20°C and 25°C, and the pressure is equal to atmospheric pressure.

[0070] Example 1: detection of the presence of alprazolam and diazepam in a Evian water solution without stirring

[0071] In this example, a sensor is immersed in static conditions at the bottom of a polypropylene glass comprising: - 100 ml of Evian water - 100 ml of Evian water and 1 mg of alprazolam powder, or - 100 ml of Evian water and 2 mg of liquid diazepam.

[0072] It comprises an Ew electrode (ultra-pure and dense graphite), an Eref electrode (platinum) and an Ec electrode (electrode with a platinum coating).

[0073] The polarization voltage applied to the working electrode Ew is a staircase potential sweep, the value of the potential at the start of the sweep being equal to -0.3 V / Pt and the value of the potential at the end of the sweep being equal to -1.5 V / Pt. The step E of the staircase is equal to -10 mV, the amplitude of the wave is equal to 50 mV.

[0074] During the first sweep B1, the plateau time (half-period) of the square wave is 25 ms (i.e. a frequency f1 equal to 20 Hz) and during the second sweep B2, the plateau time is 200 ms, i.e. a frequency f2 equal to 2.5 Hz). A first voltammogram is recorded during sweep B1 and a second voltammogram during sweep B2, of the differential current generated at each period, as a function of the value of the potential at mid-height of the direct pulse. Figures 2A, 2B and 2C represent the superposition of the two voltammograms (B1 in bottom and B2 top)

[0075] Results:

[0076] It can be seen that in the glass of water, at low frequency f2, a peak is visible around -0.7V / Pt: it corresponds to the reduction of oxygen, which does not pose a problem because the detection range of benzodiazepines is between -0.85 V / Pt and -1.35 V / Pt.

[0077] Concerning the glass containing 1 mg of alprazolam, the peak is visible at low frequency f2 around -1.2V / Pt because its reduction of this molecule in water is slow. It is observed that the intensity of the current observed with alprazolam is lower because powdered benzodiazepines are poorly soluble in water.

[0078] As for diazepam, it is visible at high and low frequency, the intensity of the differential current being much higher at low frequency.

[0079] Example 2: detection of the presence of alprazolam in an Evian water solution in agitated mode

[0080] A single scan in accordance with scan B2 described in Example 1 (frequency f2 equal to 2.5 Hz) was carried out with the same sensor in 100 ml of Evian water and 1 mg of powdered alprazolam. Throughout the scan, the solution was stirred using a straw.

[0081] Results obtained:

[0082] [Fig.3] represents the voltammogram on which it is observed that agitation induces noise but does not prevent the detection of alprazolam.

[0083] Example 3: detection of the presence of Alprazolam and Diazepam in a Vodka-Redbull® solution in static mode

[0084] The conditions of the electrical protocol of example 1 were reproduced with - 100 mL of a vodka-Redbull® mixture (25%-75% by volume), - 100 ml of a vodka-Redbull® mix (25%-75% by volume) and 1 mg of alprazolam powder, or - 100 ml of a vodka-Redbull® mixture (25%-75% by volume) and 2 mg of liquid diazepam.

[0085] Results obtained:

[0086] Figures 4A, 4B and 4C represent the superposition of the two voltammograms (B1 at the bottom and B2 at the top) obtained for each of the three liquids.

[0087] First, a peak at -1.4V / Pt is observed in vodka-Redbull® alone, which is the electrochemical signature of the commercial beverage. This is not problematic because the peak is outside the reduction range of benzodiazepines. The corresponding peaks for alprazolam and diazepam are around -0.8 V / Pt.

[0088] Example 4: detection of the presence of Alprazolam and Diazepam in a Vodka-Redbull® solution in agitated mode

[0089] The measurement protocol of Example 3 was reproduced in the glass containing 100 ml of a vodka-Redbull® mixture (25%-75% by volume) and 2 mg of liquid diazepam by continuously stirring the liquid using a straw during the measurement.

[0090] Results obtained:

[0091] Agitation induces noise but does not prevent the presence of diazepam from being detected (see [Fig.5] representing the superposition of the voltammograms (B 1 at the bottom and B2 at the top).

[0092] Example 5: detection of the presence of alprazolam and diazepam in a rosé wine solution

[0093] The conditions of the electrical protocol of example 1 were reproduced with - 100 mL of rosé wine, - 100 ml of rosé wine and 1 mg of powdered alprazolam, or - 100 ml of rosé wine and 2 mg of liquid diazepam.

[0094] Results obtained:

[0095] Figures 6A, 6B and 6C represent the superposition of the two voltammograms (B1 at the bottom and B2 at the top) obtained for each of the three liquids.

[0096] Results obtained:

[0097] It can be seen that in rosé wine, the detection of benzodiazepine molecules is much more efficient at high frequency (25 ms; frequency fl equal to 20 Hz) because the peaks are more intense. This can be explained by the fact that the reduction reactions are faster in rosé wine than in the vodka-Redbull® mixture and in water. It can be calculated that the intensity of the peak is inversely proportional to the square root of the plateau time.

Claims

Claims

1. Method for detecting a benzodiazepine molecule present in a liquid, said method consisting of: - bringing the liquid comprising the benzodiazepine molecule into contact with an amperometric electrochemical sensor comprising at least one working electrode Ew, a reference electrode Eref, a counter-electrode Ec, and a potentiostatic circuit connected to each of the electrodes, - supplying the potentiostatic circuit with a current source to subject the liquid to at least two sweeps B1 and B2 in linear potential over time, each sweep B1 and B2 being carried out between a potential value VI and a potential value V2, the value V2 being less than the value VI and the speed of the sweep B1 being different from the speed of the sweep B2,- generate a signal to alert on the presence of a benzodiazepine when a current recorded during scans B1 and B2 exceeds a threshold value during at least one of the two scans B1 and B2.,

2. Method for detecting a benzodiazepine molecule according to claim 1, characterized in that the scanning speed B1 is between 10 mV / s and 100 mV / s and in that the scanning speed B2 is between 100 mV / s and 300 mV / s.

3. A method for detecting a benzodiazepine molecule according to claim 1 or 2, characterized in that each potential sweep B1 and B2 is a linear staircase potential sweep superimposed on a square wave comprising forward pulses and reverse pulses, the frequency fl of the square wave of sweep B1 being between 15 Hz and 50 Hz, and the frequency f2 of the square wave of sweep B2 being between 2 Hz and 10 Hz.

4. Method for detecting a benzodiazepine molecule according to claim 3, characterized in that the current recorded during scans B1 and B2 is equal to a differential current If-Ir, If being recorded at the end of each forward pulse and Ir being recorded at the end of each reverse pulse.

5. Method for detecting a benzodiazepine molecule according to one of the preceding claims, characterized in that the working electrode Ew is a carbon electrode.

6. Method for detecting a benzodiazepine molecule according to one of the preceding claims, characterized in that the value of the potential V1 is less than -0.3 V and in that the value of the potential V2 is greater than -1.5 V, when the reference electrode Er is made of platinum.

7. Method for detecting a benzodiazepine molecule according to one of the preceding claims, characterized in that the signal is a signal of a luminous nature.

8. Method for detecting a benzodiazepine molecule according to one of the preceding claims, characterized in that the liquid is a drink chosen from an energy drink, a mixture of alcoholic and non-alcoholic drink(s), an alcoholic drink and mineral water.

9. Amperometric electrochemical sensor configured to detect a benzodiazepine in a liquid comprising at least one working electrode Ew, a reference electrode Eref, a counter-electrode Ec, a potentiostatic circuit connected to each of the electrodes, and an alert unit configured to generate a signal, said potentiostatic circuit being configured to impose on the working electrode Ew at least two sweeps B1 and B2 in linear potential at different speeds, and the signal being generated when a current recorded during the sweeps B1 and B2 exceeds a threshold value representative of the presence of a benzodiazepine.

10. Device for detecting a benzodiazepine in a liquid, characterized in that it comprises i) an amperometric electrochemical sensor according to claim 9, ii) a container intended to contain the liquid, and iii) an electrical power source for said electrochemical sensor.

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