Method for detecting the introduction of gamma-hydroxybutyrate into a solution

Abstract

The invention relates to a method (P) for detecting the introduction of gamma-hydroxybutyrate into a solution (Sol) by means of a sensor (Capt), the sensor comprising a working electrode (Ew), a reference electrode (Eref), a counter electrode (Ec) and a potentiostatic circuit (CP) connected to the working electrode (Ew), the reference electrode (Eref) and the counter electrode (Ec), the method comprising the following steps: - alternating, by means of the potentiostatic circuit and for a predetermined duration, a bias voltage of the working electrode between a predetermined minimum voltage and a predetermined maximum voltage, the minimum voltage being chosen in a range of potentials producing a reduction current of gamma-hydroxybutyrate, the maximum voltage being chosen outside said range of potentials; - measuring, by means of the potentiostatic circuit, a current at the working electrode during said predetermined duration;and - analyze the measured current, the detection of a variation in current between a first instant and a second instant subsequent to the first instant during said time being characteristic of the introduction of gamma-hydroxybutyrate. Figure for the abstract: Fig. 1;

Description

Title of the invention: Method for detecting the introduction of gamma-hydroxybutyrate into a solution technical field

[0001] The invention relates to a method for detecting the introduction of gamma-hydroxybutyrate into a solution, and in particular to a detection method using a chemical sensor employing an electrochemical method for generating a specific electric current upon the introduction of gamma-hydroxybutyrate into a solution. Furthermore, the invention relates to a sensor for detecting the introduction of gamma-hydroxybutyrate into a solution, and in particular to a chemical sensor. Moreover, the invention relates to a container comprising a chemical sensor and enabling the detection of the introduction of gamma-hydroxybutyrate into a solution. BACKGROUND

[0002] To date, there is no device that allows the detection of the introduction of gamma-hydroxybutyrate (GHB) in a glass of beverage in real time. Most rapid GHB detection methods are optical transduction-based. These involve fluorescent or colorimetric chemical probes. Among the few fluorescent probes is "GHB Orange" [Duanting Zhai, Yong Qiao Elton Tan, Wang Xu and Young-Tae Chang, Development of a fluorescent sensor for illicit drug GHB Chem. Commun., 2014, 50, 2904-2906], in which the approach consists of taking a beverage sample and pouring it into a solution containing the fluorescent probe and preferably 50% dimethyl sulfoxide solvent. In the presence of GHB, a fluorescent signal is observed under irradiation with an ultraviolet lamp. Another similar approach uses an array of fluorescent probes immobilized in organic capsules (cucurbiturils). Each probe / capsule pair is placed in a well.After collecting a beverage sample and removing the alcohol present (which interferes with the analysis), the sample is distributed into different wells to produce a fluorescence emission that varies depending on the beverage. In the presence of GHB, a specific "colorimetric fingerprint" can be observed [Baumes, L., BuakiSogo, M., Montes-Navajas, P., Corma, A. and Garcia, H. (2010), A Colorimetry Sensor Array for the Detection of the Date-Rape Drug γ-Hydroxybutyric Acid (GHB): A Supramolecular Approach. Chemistry - A European Journal, 16: 4489-4495.]. Other colorimetric probes have also been used, leading to attempts at commercial products (DrinkSafe™ cards, DrinkSafe™ coasters, Drink Detective™ from DrinkSafe). Technology®, or EZ Test Kit for GHB from EZ Test Kits®). The principle is always the same: the liquid (the beverage) comes into contact with the probe to produce an irreversible color change. Such colorimetric probes can be embedded in plastic straws, paper substrates, and even nail polish. All these methods suffer from a lack of reliability (high false positive rate), irreversibility (single use), and require action, more or less inconvenient, from the consumer (sampling). They are not compatible with integration into a glass for real-time reading.

[0003] Another proposed approach is to carry out an electrochemical analysis. This approach was proposed by R. Jiménez-Pérez and his collaborators using platinum-based electrodes [R. Jiménez-Pérez, JM Sevilla, T. Pineda, M. Blâzquez, J. Gonzalez-Rodriguez, Electrocatalytic performance enhanced of the electrooxidation of gamma-hydroxybutyric acid (GHB) and ethanol on platinum nanoparticles surface. A contribution to the analytical determination of GHB in the presence of ethanol, Sensors and Actuators B: Chemical, Volume 256, 2018, Pages 553-563, R. Jiménez-Pérez, JM Sevilla, T. Pineda, M. Blâzquez, J. Gonzalez-Rodriguez, Study of the electro-oxidation of a recreational drug GHB (gamma hydroxybutyric acid) on a platinum catalyst-type electrode through chronoamperometry and spectro-electrochemistry, Journal of Electroanalytical Chemistry, Volume 766, 2016, Pages 141-146, R. Jiménez-Pérez, JM Sevilla, T. Pineda, M. Blâzquez, J.González-Rodnguez, Electrochemical behaviour of gamma hydroxybutyric acid at a platinum electrode in acidic medium, Electrochimica Acta, Volume 111, 2013, Pages 601-607]. The method relies on cyclic voltammetry measurements. It consists of measuring the oxidation of alcohol (ethanol) in glass. The adsorption of GHB and ethanol on the electrode surface is competitive and is rather favorable to GHB. Since the oxidation of GHB is less pronounced than that of ethanol on a platinum electrode, the measurement then consists of using the decrease in the ethanol oxidation signal observed when GHB is added to the glass and binds to the electrode under the application of a cathodic potential. This method has drawbacks: the first is that the beverage must contain a significant amount of alcohol. It is therefore only applicable to alcoholic beverages.The second, and undoubtedly most important, point is that the measurement can only be taken in static mode, that is, without agitation of the glass. The amperometric response is highly dependent on the diffusion of the substances near the electrode. This diffusion is significantly affected by the agitation of the liquid. Therefore, the measurement is only potentially reliable if the glass remains motionless for the duration of the analysis (several tens of seconds). Consequently, it is difficult to apply in real-world situations (parties, etc.) when the consumer carries their glass in their hand or frequently picks it up to drink from it. SUMMARY

[0004] In order to overcome the drawbacks of existing methods for detecting the introduction of gamma-hydroxybutyrate into a solution, the objective of the present invention is to provide a reversible method for detecting the introduction of GHB into a solution (such as a beverage). In particular, the method is implemented by a sensor that can be placed in a container (such as a glass in which the beverage is placed). The sensor must be sufficiently sensitive to trigger detection. It must also be selective, in particular so as not to cause false positives that would lead to a loss of confidence in the sensor on the part of the user. The invention is applicable to a variety of possible beverages, each of which may contain a complex mixture of different molecules, under different pH conditions. In other words, the invention makes it possible to be selective for a single molecule in a complex and variable medium.The sensor must also be reversible to allow for its reuse (and therefore that of the container) when the sensor is integrated into the container. Furthermore, the sensitive material in contact with the beverage must be made of a non-toxic material, compliant with food hygiene and safety standards, and resistant to normal conditions of use (such as washing with dish soap or in a dishwasher). The sensor is also relatively insensitive to movement or the volume of liquid in the glass. Finally, the sensor is energy-efficient so that it can be powered by a battery (preferably a button cell easily integrated into the bottom of the glass) for the duration of an event (party, wedding, etc.), typically for a minimum of about 12 hours. Indeed, the sensor according to the invention is an amperometric sensor.When a voltage is applied, a current is measured, this current being produced by the oxidation or reduction of chemical species present in the solution. Apart from powering the electronic circuit, no power-consuming components are therefore required, thus allowing the sensor to be powered by a battery.

[0005] To this end, the invention has as its first object a method for detecting the introduction of gamma-hydroxybutyrate into a solution by means of a sensor, the sensor comprising a working electrode, a reference electrode, a counter electrode and a potentiostatic circuit connected to the working electrode, the reference electrode and the counter electrode, the method comprising the following steps: - alternate, by means of the potentiostatic circuit and for a predetermined duration, a bias voltage of the working electrode between a predetermined minimum voltage and a predetermined maximum voltage, the minimum voltage being chosen in a range of potentials producing a reduction current of gamma-hydroxybutyrate, the maximum voltage being chosen outside said range of potentials; - to measure, using the potentiostatic circuit, a current at the electrode of work during the said predetermined period; and - analyze the measured current, the detection of a variation in current between a first instant and a second instant subsequent to the first instant during said analysis being characteristic of the introduction of gamma-hydroxybutyrate.

[0006] Advantageously, the invention uses relatively simple, miniaturizable, and energy-efficient electrochemical processes that can be integrated into a container (e.g., a glass) and powered by a button cell battery. The sensor's sensitive element can be made of a noble metal with good food compatibility. This element is extremely robust to exposure to beverages that can sometimes be corrosive (the average pH of many beverages is around pH 2 to pH 4). It is also compatible with hand washing or washing in a dishwasher, even with strong detergents. Another advantage of the invention is that the detection process is reversible (unlike, for example, optical dissipatives). The measurement is automatic and does not require any particular intervention from the consumer (sampling, etc., as can be seen in some colorimetric tests).Finally, compared to other types of electrochemical detection found in the literature, this method works whether the glass is static or in motion. The key innovation of this invention lies in the combination of an electrochemical sensor that is sensitive to GHB, selective within the application context, reusable, and functional in moving glass. To our knowledge, no other sensor on the market or in the scientific literature meets all these criteria simultaneously.

[0007] In one embodiment, the introduction of gamma-hydroxybutyrate is detected when the change in current is greater than or equal to a predefined value.

[0008] Advantageously, the predefined value makes it possible to avoid false positives related, for example, to user movements.

[0009] In one embodiment, the analyze step includes the following substeps: - determine an average current value corresponding to a difference between an average current value when the bias voltage of the working electrode is equal to the minimum voltage and an average current value when the bias voltage of the working electrode is equal to the maximum voltage as a function of time; - determine a first difference between the average current value at the first instant and the average current value at the second instant; and - detect the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than a first predetermined threshold.

[0010] Advantageously, these analysis substeps allow visualization in a way specifies the characteristic variations of the introduction of GHB.

[0011] In one embodiment, the analyze step comprises the following substeps: - determine an average value of the current when the bias voltage of the working electrode is equal to the maximum voltage as a function of time; - detect the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than the first predetermined threshold and the average value of the current when the bias voltage of the working electrode equal to the maximum voltage is approximately constant between the first instant and the second instant.

[0012] Advantageously, these analysis substeps allow the container's movements to be taken into account.

[0013] In one embodiment, the analysis step comprises the following substeps: - determine an average value of the current when the bias voltage of the working electrode is equal to the minimum voltage as a function of time s; - determine a second difference between the average current value at the first instant and the average current value at the second instant; and - detect the introduction of gamma-hydroxybutyrate when the absolute value of the second difference is greater than a second predetermined threshold.

[0014] Advantageously, these analysis substeps allow for precise visualization of the characteristic variations of GHB introduction even in the event of vibrations or movements of the glass.

[0015] In one embodiment, the method comprises: - if the current shows a variation, emit an alert signal.

[0016] In one embodiment, the warning signal is emitted when the variation is greater than the predefined value for a second predetermined duration.

[0017] Advantageously, the second predetermined duration makes it possible to avoid false positives due to movement of the glass or vibration.

[0018] In one embodiment, the warning signal is an audible, visual or vibrating signal.

[0019] Advantageously, the warning signal alerts the user that GHB has been introduced into the glass.

[0020] In one embodiment, the voltage range is chosen between -2.2 V / Pt and -1.6 V / Pt for the minimum voltage and -1.4 V / Pt and 0 VPt for the maximum voltage.

[0021] Advantageously, this voltage range makes it possible to ensure the reduction of GHB and thus its detection while avoiding the reduction of the water present in the solution and thus avoiding a noisy signal.

[0022] The invention also relates to a sensor for detecting the introduction of gamma-hydroxybutyrate into a solution, the sensor being placed in a container and being in contact with the solution, the sensor comprising a working electrode, an electrode reference electrode and counter electrode and a potentiostatic circuit connected to the working electrode, the reference electrode and the counter electrode, the sensor being configured to implement the method according to the first object of the invention.

[0023] In one embodiment, the working electrode being made of noble metal, preferably platinum.

[0024] Advantageously, platinum allows the sensor to be resistant to washing in dishwashers, dishwashing detergents, and the varied pH of beverages.

[0025] In one embodiment, the working electrode has a surface area between 0.002 mm2 and 100 mm2.

[0026] Advantageously, this surface makes it possible to reduce the costs associated with the electrodes.

[0027] The invention has as its third object a container enabling the detection of an introduction of gamma-hydroxybutyrate into a liquid placed in the container, the container comprising the sensor according to the second object of the invention.

[0028] In one embodiment, the container includes an alert system configured to emit the alert signal, the alert signal preferably being an audible, visual or vibrating signal.

[0029] Advantageously, the warning signal makes it possible to alert the user that GHB has been introduced into the glass. FIGURES

[0030] The invention will be better understood and other advantages will become apparent upon reading the following description, given by way of non-limiting example, and with reference to the figures, among which:

[0031] [Fig.1] [Fig.1] illustrates a method for detecting the introduction of gamma-hydroxybutyrate into a solution according to the invention;

[0032] [Fig.2a] [Fig.2a] illustrates an example of current measured according to the invention;

[0033] [Fig.2b] [Fig.2b] illustrates an example of current measured according to the invention;

[0034] [Fig.3a] [Fig.3a] illustrates an example of current measured according to the invention;

[0035] [Fig. 3b] [Fig. 3b] illustrates an example of current analysis measured according the invention;

[0036] [Fig.3c] [Fig.3c] illustrates an example of current analysis measured according to the invention

[0037] [Fig.3d] [Fig.3d] illustrates an example of current analysis measured according the invention;

[0038] [Fig.4a] [Fig.4a] illustrates an example of current measured according to the invention;

[0039] [Fig.4b] [Fig.4b] illustrates an example of current analysis measured according the invention;

[0040] [Fig.4c] [Fig.4c] illustrates an example of current analysis measured according to the invention

[0041] [Fig.4d] [Fig.4d] illustrates an example of current analysis measured according to the invention;

[0042] [Fig. 5] [Fig. 5] illustrates an example of a sensor according to the invention; and

[0043] [Fig.6] [Fig.6] illustrates an example of a container according to the invention. DETAILED DESCRIPTION

[0044] The invention relates to a method for detecting the introduction of gamma-hydroxybutyrate into a solution. Figure 1 illustrates a detection method according to the invention.

[0045] The method for detecting the introduction of gamma-hydroxybutyrate (GHB) into a Sol solution is implemented by means of a Capt sensor, the sensor comprising a working electrode Ew, a reference electrode Eref, a counter electrode Ec and a potentiostatic circuit CP connected to the working electrode Ew, the reference electrode Eref and the counter electrode Ec.

[0046] Gamma-hydroxybutyrate (GHB) can be added to a solution (e.g., a beverage) in solid form (powder, capsule) or in liquid form after it has been dissolved, for example, in a little water. The dose of GHB required for an act of drug-facilitated sexual assault depends on several factors: the weight and sex of the potential victim, whether the victim is under the influence of alcohol, etc. However, in general, it is considered that the average dose to be administered to a person to induce drug-facilitated sexual assault is around 1 gram.

[0047] The Sol solution can be, for example, a liquid such as a beverage (alcoholic or non-alcoholic, or a mixture of alcoholic and non-alcoholic beverages). A beverage can be any type of drinkable beverage, for example: juices (orange juice, multi-fruit, etc.), colas, energy drinks (drinks based on caffeine and taurine), lemonades, alcoholic beverages such as wines (red, white, rosé, sparkling or still, crémants, champagnes), beers, spirits (whiskey, vodka, gin, tequila, etc.), or cocktails based on spirits and non-alcoholic beverages (juices, lemonades, cola, energy drinks, etc.).

[0048] The working electrode Ew is composed of a noble metal such as platinum, iridium, palladium, gold, or an alloy of these metals. Preferably, the electrode chosen will be platinum. Advantageously, platinum allows for the generation of a higher current than other materials while having a lower cost. The working electrode Ew can be found in a wide variety of shapes and sizes: wire, disc, pin, thin film deposited on another metal or charge collector, etc. The surface area of ​​the working electrode Ew can typically range from 0.002 mm² to 100 mm². The counter electrode (or auxiliary electrode) can be in the form of any The counter electrode should be a metal resistant to the conditions of use of a container housing the electrodes (e.g., dishwashing products, corrosive acidic beverages, etc.), such as the same metals as the working electrode Ew, or stainless steel. Preferably, the counter electrode is made of platinum. The surface area of ​​the counter electrode Ec is preferably at least as large as that of the working electrode Ew. Generally, the reference electrode Eref has a potential that remains practically constant 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 in the form of AgIAgCl, a calomel electrode, etc. However, these are difficult to implement for the intended applications (high cost, long-term stability issues in beverages, fragility under operating conditions, incompatibility with dishwashers, etc.).Therefore, preferably, the reference electrode Eref can be a pseudo-reference electrode. Platinum offers good performance for this purpose, as do most metals in the platinum group. Since this electrode is only present to provide a reference potential, its size is not critical.

[0049] The electrodes Ew, Ec, Eref can for example be part of a sensor Capt which itself is part of a container (such as a glass) in which the Sol solution is placed.

[0050] To perform the measurements, the three electrodes Ew, Ec, Eref must be positioned in the solution Sol (for example, the beverage). Thus, when using a glass, positioning at the bottom of the glass is preferred. The spacing between the electrodes is not critical. However, it is preferable to place the electrodes as close together as possible to facilitate the flow of current in the circuit. Indeed, if the ionic conductivity of the solution is low, it will be more difficult for the current to flow in the circuit if the electrodes are far apart. In one example, the electrodes are placed close together in the center of the container Cont containing them. Thus, the electrodes can be immersed, even when the container is tilted (for example, when a user of the container is drinking).

[0051] In block El, the process includes the step of alternating, by means of the potentio-static circuit CP and for a predetermined duration, a bias voltage of the working electrode between a predetermined minimum voltage and a predetermined maximum voltage, the minimum voltage being chosen in a range of potentials producing a reduction current of gamma-hydroxybutyrate, the maximum voltage being chosen outside said range of potentials.

[0052] In particular, the bias voltage of the working electrode Ew is alternated between two distinct potentials, one in the range of potentials producing a GHB reduction current, and the other in a range of lower potentials (closer (from zero). For example, the bias voltage of the working electrode Ew can be varied between a maximum voltage in the range of -1.4 V / Pt to 0 and a minimum voltage in the range of -1.6 V / Pt to -2.2 V / Pt. The bias voltage range may depend on the pH of the Sol solution. Indeed, the reference potential varies with the pH of the Sol solution.

[0053] Regarding the minimum voltage value, below -1.6 V / Pt, the voltage value may be too low (in absolute value), and thus the reduction of GHB does not occur, and its detection therefore cannot take place. Above -2.2 V / Pt, the voltage is close to the value at which water begins to electrolyze, and the electrode then reduces the water present in the Sol solution. This causes bubbles to form on the electrode, which in turn generates a noisy signal. Regarding the maximum voltage, applying a voltage between 0 and -1.4 V / Pt has little influence on the response. Above -1.4 V, GHB begins to be reduced, and therefore the difference in current produced for the two voltage values, 0 V / Pt and -1.4 V / Pt, decreases. Consequently, the sensitivity of the measurement decreases.

[0054] The potentiostatic voltage alternates between a minimum voltage and a maximum voltage, each with a predetermined pulse duration. For example, the pulse duration of the minimum and maximum voltages can be between 1 s and 5 s. This range of pulse durations optimizes the sensor's sensitivity while also optimizing the response time.

[0055] In block E2, the method P includes the step of measuring, by means of the potentiostatic circuit, a current at the working electrode Ew during said predetermined duration.

[0056] For example, the direct current is measured over the predetermined time period.

[0057] In block E3, the process P includes the step of analyzing the measured current, the detection of a variation in the current between a first instant and a second instant subsequent to the first instant during said analysis being characteristic of the introduction of gamma-hydroxybutyrate.

[0058] The current showing a variation in the presence of GHB is a GHB reduction current.

[0059] To illustrate the process P, an example is presented in figures 2a-2b.

[0060] In this example, the electrodes Ew, Eref, and Ec are immersed in a glass containing a mixture of 70% energy drink and 30% vodka with an alcohol content of 40% vol. The drink is continuously stirred using a magnetic stirrer. The bias voltage of the working electrode Ew is alternated every 2 seconds between -0.8 V / Pt and -1.6 V / Pt. At time tx = 200 s, 1 g of GHB per 200 mL of the drink is added to the glass.

[0061] The resulting current is measured at the working electrode Ew and the [Fig.2a] is obtained. The upper part of the curve in [Fig.2a] represents the current measured when the potentiostatic voltage is at its maximum and the lower part of the curve represents the potentiostatic voltage is at its minimum.

[0062] As shown in [Fig.2a], a current is observed when GHB is added at tx=200 s compared for example to time tn, time tn being prior to time tx.

[0063] In one example, the introduction of gamma-hydroxybutyrate is detected when the current change is greater than or equal to a predefined value. For example, the predefined value could be a percentage change on the curve. For example, if the current changes by more than 2%, the introduction of gamma-hydroxybutyrate is detected. In another example, a threshold could be defined based on the electrodes used, the solution used, and the potentiostatic voltage used.

[0064] For example, in the example of [Fig.2a], a threshold can be predefined and when the current is below the predefined threshold, this means that GHB has been introduced into the Sol solution.

[0065] In one example, step E3 of analyzing the measured current may include the substep of determining an average current value corresponding to the difference between an average current value when the bias voltage of the working electrode Ew is equal to the minimum voltage and an average current value when the bias voltage of the working electrode Ew is equal to the maximum voltage as a function of time. The variation of the average current value between a first instant and a second instant subsequent to the first instant during said analysis is characteristic of the introduction of gamma-hydroxybutyrate.

[0066] As illustrated in [Fig. 2b], another way to visualize the data is to subtract the average current value measured during a polarization at -1.6 V / Pt from the average current value measured during the next polarization at -0.8 V / Pt over the duration of the experiment. [Fig. 2b] is then obtained, in which a very significant amplitude variation is indeed observed between the time tn before the addition of GHB and at time tx when GHB is added, despite the agitation of the beverage.

[0067] In another example, step E3 of analyzing the measured current may also include the substep of determining a first difference between the average value of the current at the first instant and the average value of the current at the second instant and detecting the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than a first predetermined threshold.

[0068] Thus, when the average value is determined, a difference between the average current value at time tx and time tn can be calculated. If this difference is greater than a threshold that has been predetermined based on the electrodes used, the solution used, and the potentiostatic voltage used, this indicates that there is presence of GHB.

[0069] In order to illustrate the process P, another example is presented in figures 3a-3d.

[0070] In this example, the electrodes Ew, Eref, Ec are immersed in a glass The experiment consists of a mixture of 70% energy drink and 30% vodka with an alcohol content of 40% vol. The bias voltage of the working electrode is alternated every 2 seconds between -0.8 V / Pt and -1.6 V / Pt. The glass is handled during the period from t0 to t1 = 0-100 s. When the glass is handled, this causes a slight agitation of the drink. The glass is then placed on a table between t1 = 100 s and t2 = 150 s, then handled again between t2 = 150 s and t3 = 300 s, placed back on the table at t3 = 300 s, and finally handled again at t4 = 350 s until the end of the experiment. At tx = 200 s, the equivalent of 1 g of GHB in 200 mL of the drink is added to the glass.

[0071] The current is measured and shown in [Fig. 3a]. When GHB is introduced at tx = 200 s, a change in the current is observed due to the reduction reaction upon introduction of GHB.

[0072] However, it can be observed that agitation of the glass (glass at rest on the table and handling the glass) also causes variations in the measured current. Indeed, an increase in current is observed when the bias voltage is equal to -0.8 V / Pt when the glass is placed on the table, in the presence or not of GHB (the upper part of the curve in [Fig. 3a] represents the current measured when the potentiostatic voltage is maximum (here -0.8 V / Pt) and the lower part of the curve represents the current when the potentiostatic voltage is minimum (here -1.6 V / Pt).

[0073] Thus, as in the example of [Fig. 2b], searching for an increase in current corresponding to the subtraction of the average current value measured during a bias at -1.6 V / Pt from the average current value measured during the following bias at -0.8 V / Pt can lead to false positives. Indeed, the amplitude also increases when the glass is placed on the table, whether or not GHB is present.

[0074] Furthermore, when the bias voltage is equal to -1.6 V / Pt in the presence of GHB, a decrease in current occurs, as observed in the preceding example in [Fig. 2a]. The current evolution when the bias voltage is equal to -1.6 V / Pt in the presence of GHB appears relatively insensitive to whether the glass is shaken or not. Thus, the lower part of the curve representing the current when the potentiostatic voltage is at its minimum can be used alone to determine whether GHB has been introduced.

[0075] Thus, in the example of [Fig. 3d], the lower part of the curve of [Fig. 3a] is analyzed. In order to obtain [Fig. 3d], the analysis step E3 comprises the following substeps:

[0076] A substep consists of determining an average value of the current when the The bias voltage of the working electrode is equal to the minimum voltage over time. For example, the average current value can be measured over a predetermined period. In particular, the lower part of the curve can be smoothed by averaging several points when the bias voltage is -1.6 V. For example, an average of 10 points can be calculated. Hereafter, a point refers to a value taken on the curve at a specific point on that curve.

[0077] A substep consists of determining a second difference A2 between the average current value at the first instant and the average current value at the second instant as a function of time. For example, the second difference A2 is determined between the instants tx and t0.

[0078] A substep consists of detecting the introduction of gamma-hydroxybutyrate when the absolute value of the second difference A2 is greater than a second predetermined threshold. For example, the predetermined value may be the second predetermined threshold.

[0079] Thus, in [Fig. 3d], it is observed that the average current value remains unchanged even when the glass is picked up or placed on the table. However, a variation is indeed observed when GHB is introduced. This variation can be characterized by determining the difference A2 between two average current values ​​at two different times, the difference A2 being compared to a threshold which can be a predefined value.

[0080] In another example, as shown in [Fig. 3b], the analyze step may include the following substeps:

[0081] As also shown in the example in [Fig. 2b], a substep may include determining an average current value corresponding to the difference between an average current value when the bias voltage of the working electrode is equal to the minimum voltage and an average current value when the bias voltage of the working electrode is equal to the maximum voltage, as a function of time. For example, the lower part of the curve can be smoothed by averaging several points when the bias voltage is equal to -1.6 V. For example, an average of 10 points can be calculated. Similarly, the upper part of the curve can be smoothed by averaging several points when the bias voltage is equal to -0.8 V. For example, an average of 10 points can be calculated. The difference between the two averages is then calculated and plotted as a function of time.

[0082] A substep comprises determining a first difference Al between the average current value at the first instant and the average current value at the second instant. For example, the difference Al between the average current value is determined between instants tx and t0.

[0083] A substep may include detecting the introduction of gamma-hy- droxybutyrate is affected when the absolute value of the first difference Al is greater than a predetermined first threshold. For example, the predetermined value could be the first predetermined threshold. The first and second thresholds could be the same.

[0084] As indicated above, this analysis makes it possible to determine whether there has been a variation in the current. However, variations in the current can be caused by the introduction of GHB or by vibrations of the glass.

[0085] Thus, in order to avoid false positives, the analysis step comprises the following sub-steps:

[0086] A substep involves determining an average current value when the bias voltage of the working electrode is equal to the maximum voltage as a function of time. In particular, the upper part of the curve in [Fig. 3a] represents the bias voltage of the working electrode equal to the maximum voltage (in this example -0.8 V) as a function of time. This substep consists of smoothing this part of the curve. The average of several points is calculated when the bias voltage is equal to -0.8 V. For example, an average of 10 points can be taken. The resulting curve is plotted in [Fig. 3c].

[0087] A substep includes detecting the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than the first predetermined threshold and the average current value when the bias voltage of the working electrode, equal to the maximum voltage, is approximately constant between the first and second instants. The maximum voltage can be approximately constant when it is below a predetermined threshold. In other words, if, for the same period, the curve in [Fig. 3c] is approximately constant but the curve in [Fig. 3b] shows a first difference that is greater than the first threshold, then GHB has been introduced. Conversely, if, for the same period, the curve in [Fig. 3c] shows a variation and the curve in [Fig. 3b] shows a first difference that is greater than the first threshold, then GHB has not been introduced but the glass has been moved.For example, the variation of the curve in [Fig.3c] can be a difference between two instants compared to a predetermined threshold.

[0088] Thus, in order to avoid false positives, the analysis steps allowing us to obtain figures 3b and 3c can be combined.

[0089] Furthermore, to obtain a more precise method, it is possible to combine the analysis steps used to obtain Figures 3b, 3c, and 3d. For example, the method used to obtain the curve in [Fig. 3d] makes it possible to determine if there is a variation representing the introduction of GHB. To confirm this result, the method used to obtain the curve in [Fig. 3b] can be performed to confirm the variation in current over the same period of time. In addition, it is It is possible to verify whether the variation obtained by the method for obtaining the curve in [Fig.3b] is not only the result of a movement of the container by applying the method for obtaining the curve in [Fig.3c].

[0090] It is noted that the thresholds described above and the variations can also be percentages of increase or decrease of the current.

[0091] In order to illustrate the process P in more detail, another example is shown in figures 4a to 4g.

[0092] In another example, the electrodes Ew, Eref, and Ec are immersed in a glass containing a mixture of 70% orange juice and 30% vodka with an alcohol content of 40% vol. The bias voltage of the working electrode is alternated every 2 seconds between -0.8 V / Pt and -1.6 V / Pt. The glass is held in the hand during the period between t1 = 100 s and t2 = 150 s, and then again between t2 = 300 s and t3 = 350 s. The rest of the time, it rests on the table. At tx = 200 s, the equivalent of 1 g of GHB in 200 mL of the beverage is added to the glass.

[0093] The current is measured and shown in [Fig.4a]. When GHB is introduced at tx = 200 s, a change in the current is observed.

[0094] However, it can be observed that agitation of the glass (glass at rest on the table and handling the glass) also causes variations in the current. Indeed, an increase in current is observed when the bias voltage is equal to -0.8V when the glass is handled, in the presence or absence of GHB (the upper part of the curve in [Fig. 4a] represents the current measured when the potentiostatic voltage is maximum (here -0.8 V / Pt) and the lower part of the curve represents the current when the potentiostatic voltage is minimum (here -1.6 V / Pt).

[0095] Thus, as in the example of [Fig. 2b] and 3b, searching for an increase in current corresponding to the subtraction of the average current value measured during a bias at -1.6 V / Pt from the average current value measured during the following bias at -0.8 V / Pt can lead to false positives. Indeed, the amplitude also increases when the glass is placed on the table, whether or not GHB is present.

[0096] Furthermore, when the bias voltage is equal to -1.6 V / Pt in the presence of GHB, a decrease in current appears, as observed in the preceding example in [Fig. 2a]. The current evolution when the bias voltage is equal to -1.6 V / Pt in the presence of GHB seems relatively insensitive to whether the glass is shaken or not. Thus, once again, the lower part of the curve representing the current when the potentiostatic voltage is at its minimum can be used alone to determine whether GHB has been introduced.

[0097] Thus, in the example of [Fig. 4d], the lower part of the curve in [Fig. 3a] is analyzed. In order to obtain [Fig. 4d], the analysis step E3 comprises the following substeps:

[0098] A substep consists of determining an average current value when the bias voltage of the working electrode is equal to the minimum voltage as a function of time. For example, the average current value can be measured over a predetermined period. In particular, the lower part of the curve can be smoothed by averaging several points when the bias voltage is equal to -1.6 V. For example, an average of 10 points can be calculated.

[0099] A substep consists of determining a second difference A2 between the average current value at the first instant and the average current value at the second instant as a function of time. For example, the second difference A2 is determined between the instants t0 and tx.

[0100] A substep consists of detecting the introduction of gamma-hydroxybutyrate when the absolute value of the second difference A2 is greater than a second predetermined threshold. For example, the second predetermined threshold may be the predefined value.

[0101] Thus, in [Fig. 4d], it is observed that the average current value remains unchanged even when the glass is picked up or placed on the table. However, a variation is indeed observed when GHB is introduced. This variation can be characterized by determining the second difference A2 between two average current values ​​at two different times, the second difference A2 being compared to a threshold which can be the predefined value.

[0102] In another example, as observed in [Fig.4b], the analyze step may include the following substeps:

[0103] As also shown in the example in Figures 2b and 3b, a substep may include determining an average current value corresponding to the difference between an average current value when the bias voltage of the working electrode is equal to the minimum voltage and an average current value when the bias voltage of the working electrode is equal to the maximum voltage, as a function of time. For example, the lower part of the curve may be smoothed by averaging several points when the bias voltage is equal to -1.6 V. For example, an average of 10 points may be calculated. Similarly, the upper part of the curve may be smoothed by averaging several points when the bias voltage is equal to -0.8 V. For example, an average of 10 points may be calculated. The difference between the two averages is then calculated and plotted as a function of time.

[0104] A substep includes determining a first difference Al between the average current value at the first instant and the average current value at the second instant. For example, the first difference Al between the average current value is determined between instants t0 and tx.

[0105] A substep may include detecting the introduction of gamma-hydroxybutyrate when the absolute value of the first difference Al is greater than a first threshold predetermined. For example, the predetermined value could be the first predetermined threshold. The first and second thresholds could be the same.

[0106] As indicated above, this analysis makes it possible to determine whether there has been a variation in the current. However, variations in the current can be caused by the introduction of GHB or by vibrations of the glass.

[0107] Thus, in order to avoid false positives, the analysis step comprises the following sub-steps:

[0108] A substep involves determining an average current value when the bias voltage of the working electrode is equal to the maximum voltage as a function of time. In particular, the upper part of the curve in [Fig. 4a] represents the bias voltage of the working electrode equal to the maximum voltage (in this example -0.8 V) as a function of time. This substep consists of smoothing the upper part of the curve. The average of several points is calculated when the bias voltage is equal to -0.8 V. For example, an average of 10 points can be taken. The resulting curve is plotted in [Fig. 4c].

[0109] A substep includes detecting the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than the first predetermined threshold and the average value of the current when the bias voltage of the working electrode, equal to the maximum voltage, is approximately constant between the first and second instants. The maximum voltage can be approximately constant when it is below a predetermined threshold. In other words, if, for the same period, the curve in [Fig. 4c] is approximately constant but the curve in [Fig. 4b] shows a first difference that is greater than the first threshold, then GHB has been introduced. Conversely, if, for the same period, the curve in [Fig. 4c] shows a variation and the curve in [Fig. 4b] shows a first difference that is greater than the first threshold, then GHB has not been introduced but the glass has been moved.For example, the variation of the curve in [Fig.4c] can be a difference between two instants compared to a predetermined threshold.

[0110] As previously stated, in order to avoid false positives the analysis steps to obtain figures 4b and 4c or 4b, 4c and 4d can be combined.

[0111] In one embodiment, the method includes the following step: if the current exhibits a variation, emitting an alert signal. Thus, the user can be informed of the introduction of GHB into their drink. For example, the alert signal can be emitted when the variation exceeds a predefined value for a second predetermined duration. For example, the alert signal can be emitted when the variation exceeds a predefined value for 10 seconds or more. The alert signal can be an audible, visual, or vibrating signal. For example, when it is detected that GHB has been introduced into a user's drink, a vibrating signal can be emitted in order to to inform the user that GHB has been introduced into their drink.

[0112] The invention also relates to a sensor for detecting the introduction of gamma-hydroxybutyrate into a solution. Figure 5 illustrates an example of a sensor according to the invention.

[0113] The Capt sensor for detecting the introduction of gamma-hydroxybutyrate into a Sol solution is placed in a container Cont and is in contact with the Sol solution. The sensor comprises a working electrode Ew, a reference electrode Eref, and a counter electrode Ec, and a potentiostatic circuit CP connected to the working electrode Ew, the reference electrode Eref, and the counter electrode Ec. The Capt sensor is configured to implement the method P described above.

[0114] In one embodiment, the working electrode Ew is made of a noble metal, preferably platinum. The use of a noble metal allows the sensor to withstand operating conditions such as washing in a dishwasher, household cleaning products, acidic beverages, etc. Furthermore, the sensor is reusable. In one example, all three electrodes Ew, Ec, and Eref are made of platinum.

[0115] In one embodiment, the working electrode has a surface area between 0.002 mm² and 100 mm². Below 0.002 mm², the working electrode is a microelectrode. The measured current from microelectrodes is low and therefore requires more expensive electronics (such as the use of amplifiers). Moreover, in the case of carbonated beverages, the accumulation of a bubble on a microelectrode could significantly disrupt the measurement signal. However, since platinum is an expensive material, it may be advantageous to limit the electrode size to 100 mm², for example.

[0116] The invention also relates to a Cont container for detecting the introduction of gamma-hydroxybutyrate into a sol solution. Figure 6 illustrates an example of a Cont container according to the invention.

[0117] The container Cont allowing the detection of an introduction of gamma-hydroxybutyrate into the Sol solution placed in the container Cont, includes the sensor Capt described above.

[0118] In one embodiment, the container Cont includes an alert system SA configured to emit the alert signal, the alert signal preferably being an audible, visual, or vibrating signal. In another embodiment, the sensor Capt includes the alert system SA.

[0119] The application relates to the integration of a Capt sensor implementing the method P of the invention described above, which would be integrated into a glass of beverage to allow the consumer to be informed as quickly as possible of the introduction of GHB into their drink. It is primarily aimed at the events sector (nightclubs, caterers, festive environments in general, sporting events, etc.).

[0120] Although the invention has been illustrated and described in detail using a preferred embodiment, the invention is not limited to the disclosed examples. Other variations can be deduced by a person skilled in the art without departing from the scope of protection of the claimed invention. For example, the examples of beverages used serve only to illustrate the application.

Claims

Claims

1. Method for detecting (P) the introduction of gamma-hydroxybutyrate into a solution (Sol) by means of a sensor (Capt), the sensor comprising a working electrode (Ew), a reference electrode (Eref), a counter-electrode (Ec) and a potentiostatic circuit (CP) connected to the working electrode (Ew), the reference electrode (Eref) and the counter-electrode (Ec), the method comprising the following steps: - alternating, by means of the potentiostatic circuit and for a predetermined duration, a polarization voltage of the working electrode between a predetermined minimum voltage and a predetermined maximum voltage, the minimum voltage being chosen from a range of potentials producing a reduction current of the gamma-hydroxybutyrate, the maximum voltage being chosen outside said range of potentials; - measuring, by means of the potentiostatic circuit, a current at the working electrode for said predetermined duration;and - analyzing the measured current, a detection of a variation in the current between a first instant and a second instant subsequent to the first instant during said analysis being characteristic of the introduction of gamma-hydroxybutyrate.;

2. The detection method according to claim 1, wherein the introduction of gamma-hydroxybutyrate is detected when the variation of the current is greater than or equal to a predefined value.

3. Detection method according to one of the preceding claims, the step of analyzing the measured current comprising the following sub-steps: - determining an average value of the current corresponding to a difference between an average value of the current when the polarization voltage of the working electrode is equal to the minimum voltage and an average value of the current when the polarization voltage of the working electrode is equal to the maximum voltage as a function of time; - determining a first difference between the average value of the current at the first instant and the average value of the current at the second instant; and - detecting the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than a first predetermined threshold.

4. A detection method according to claim 3, the step of analyzing the measured current comprising the following sub-steps: - determining an average value of the current when the polarization voltage of the working electrode is equal to the maximum voltage as a function of time; - detecting the introduction of gamma-hydroxybutyrate when the absolute value of the first difference is greater than the first predetermined threshold and the average value of the current when the polarization voltage of the working electrode equal to the maximum voltage is approximately constant between the first instant and the second instant.

5. Detection method according to one of the preceding claims, the step of analyzing the measured current comprising the following sub-steps: - determining an average value of the current when the polarization voltage of the working electrode is equal to the minimum voltage as a function of time; - determining a second difference between the average value of the current at the first instant and the average value of the current at the second instant; and - detecting the introduction of gamma-hydroxybutyrate when the absolute value of the second difference is greater than a second predetermined threshold.

6. Detection method according to one of the preceding claims, the method comprising: - if the current shows a variation, emitting an alert signal.

7. A detection method according to claim 6, wherein the alert signal is emitted when the variation is greater than the predefined value for a second predetermined duration.

8. Detection method according to one of claims 6 or 7, in which the alert signal is an audible, luminous or vibrating signal.

9. Detection method according to one of the preceding claims, in which the voltage range of the working electrode is chosen between -2.2 V / Pt and -1.6 V / Pt for the minimum voltage and -1.4 V / Pt and 0 V / Pt for the maximum voltage, the reference electrode being made of platinum.

10. Sensor (Capt) for detecting the introduction of gamma-hydroxybutyrate into a solution (Sol), the sensor being placed in a container (Cont) and being in contact with the solution, the sensor comprising a working electrode (Ew), a reference electrode (Eref) and a counter electrode (Ec) and a potentiostatic circuit (CP) connected to the working electrode (Ew), to the reference electrode (Eref) and to the counter electrode (Ec), the sensor being configured to implement the method according to one of claims 1 to 5.

11. Detection sensor (Capt) according to claim 10, the working electrode being made of noble metal, preferably platinum.

12. A detection sensor (Capt) according to claim 10 or claim 11, the working electrode having a surface area of between 0.002 mm2 and 100 mm2.

13. Container (Cont) allowing the detection of an introduction of gamma-hydroxybutyrate into a solution (Sol) placed in the container (Cont), the container comprising the sensor of claims 10 to 12.

14. Container according to the preceding claim, the container comprising an alert system (SA) configured to emit the alert signal, the alert signal preferably being an audible, luminous or vibrating signal.

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