Synthetic cannabinoid detection

Abstract

Aspects and embodiments described relate to an apparatus and methods to identify presence of a substance of interest, for example, a synthetic cannabinoid, adsorbed onto, or absorbed into, a physical matrix. One aspect provides an apparatus configured to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix. The apparatus comprises: an irradiation source configured to illuminate a sample comprising the physical matrix at an excitation wavelength, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; and at least one emission collection element configured to collect emission from the sample. The apparatus further comprises a controller configured to assess the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, to trigger an alert indicative of positive identification of presence of the substance of interest on the sample comprising the physical matrix. Also described are various methods of assessment of collected emission to determine the likely presence, or otherwise, of a substance of interest on the physical matrix.

Description

[0001] SYNTHETIC CANNABINOID DETECTION

[0002] FIELD OF THE INVENTION

[0003] Aspects and embodiments relate to an apparatus and methods to identify presence of a substance of interest, for example, a synthetic cannabinoid, adsorbed onto or absorbed into, a physical matrix.

[0004] BACKGROUND

[0005] Synthetic cannabinoid receptor agonists (SCRAs), often termed ‘spice’ are a class of novel psychoactive substances (NPS) and take the form of molecules that emulate effects of an active ingredient of marijuana. SCRAs have gained popularity over the last decade and are predominantly used by subjects in prisons and homeless communities.

[0006] SCRAs can have very severe side effects, including psychosis, stroke, seizures and there are numerous reported deaths associated with their use. The chemical diversity of SCRAs (> 250 known) presents the major challenge to their detection, since approaches relying on specific molecular recognition become outdated almost immediately.

[0007] Drug identification techniques are known. Known devices and methods, for example NMR, are often very precise, take a long time, and require personnel with specific scientific backgrounds. Mass spectrophotometry is also used for chemical identification of compounds. However, it will be appreciated that such an approach cannot be in place in most settings where detection is most critical, for example, hospitals, safe houses, prisons, and in the field. Accordingly, healthcare actions, legal actions and court proceedings depending on spice detection and / or spice compound identification are often deemed inefficient and ineffective.

[0008] SCRA detection can be more challenging since the majority of SCRAs enter, for example, a prison setting, or general use, by being adsorbed onto some physical matrix such as paper, fabric, herb material, or mixed into vape liquid. As a result, regardless of the detection or identification modality used, often some extraction step is required, necessarily reducing the effectiveness and ability of screening material onsite. Detection of likely presence of a substance of interest on a physical matrix can be challenging. It is desired to provide an apparatus and methodologies which can address such challenges.

[0009] SUMMARY

[0010] According to some, but not necessarily all, aspects, there is provided a method of assessing whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the method comprising: irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; collection of emission from the sample; assessing the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, triggering a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0011] Synthetic cannabinoid receptor agonists (SCRAs) also known as “Spice” or “K2” are a structurally diverse class of novel psychoactive substances (NPS). Over 250 SCRAs are known and their structure typically is adapted to track with any trend in global legislation to prevent or restrict their use. In general, SCRAs are defined as having a ‘tail’, ‘core’, ‘linker’ and ‘linked’ moiety, each of which are synthetically interchangeable whilst often retaining agonism of CB1 and CB2 receptors.

[0012] In the UK, SCRAs are the dominant novel psychoactive substance (NPS) used within the prison estate. The majority of prison residents in England have used SCRAs. The side effects of SCRAs are debilitating and can include, for example, psychosis, stroke, and seizures. Users of SCRAs may experience increased aggression. Enhanced detection of SCRAs may offer a mechanism by which it is possible to alleviate the operational challenges of NPS, including SCRAs, and their use in the prisons.

[0013] SCRA soaked into personal mail is a well-established mechanism of entry of SCRAs into prisons. To some extent, entry to the prison via this route can be effectively ameliorated through screening of personal mail and photocopying. However, in the UK routes also exist such as ‘Rule 39’ mail sent from legal professionals to prison residents, and which is passed directly to residents. Moreover, as drug entry routes through mail have decreased, alternatives including soaking SCRAs into fabric, ‘street’ herb material, and other matrices, entry of such material via ‘throw-overs’ and staff corruption and similar are growing in prevalence.

[0014] Fluorescence is a known technology for the detection of organic substances and mixtures in or on various matrixes. However, the range of SCRAs and therefore the range of SCRA spectra make use of fluorescence techniques an unusual candidate for drug detection. Nonetheless, aspects and embodiments recognise that a fluorescence approach can be provided and act as a real-time monitor for the presence of an SCRA.

[0015] The inventors have previously demonstrated that synthetic cannabinoid receptor agonists (SCRAs) can be accurately detected using fluorescence spectral fingerprints (FSF); enumerated excitation emission matrices. The inventors determined that FSFs are discriminatory of SCRAs both generically and as structural classes. An example FSF is shown in Figure 1A.

[0016] The FSF approach has best utility where the SCRA is present in a complex matrix, for example, saliva, where spectral deconvolution from a complex background (for example, salivary protein emission arising from intrinsic tryptophan residues) is needed. Such detection may have particular utility as a point-of-care analysis mechanism, allowing assessment of patients who are non-responsive but are suspected of SCRA use.

[0017] Figure 1 A shows schematically a typical FSF of an SCRA. The FSF has a major emission band centred at ~350nm. This is the case for the vast majority of SCRAs surveyed across diverse structural classes, including the most recent iterations of seized SCRAs, such as ‘tailless’ molecules. The emission wavelength is broadly defined by the nature of the core moiety, for example typically indole or indazole based and more recent variants have been found to show a similar emission profile, i.e. an emission profile broadly centred at -350 nm.

[0018] Figure 1 B illustrates various examples of SCRAs showing the range of ‘core’ moieties. The vast majority of SCRAs observed across all major structural classes have been found to exhibit a similar structured emission band centred at -350 nm.

[0019] The inventors have recognised that SCRA fluorescence is observable, and deconvolved from autofluorescence of the physical substrate onto which it is adsorbed, provided a sample is irradiated with a sufficiently intense irradiation source, and provided the wavelength of the irradiation source is carefully selected to allow observation of the SCRA fluorescence. Aspects and embodiments recognise that the methodology identified by the inventors can be implemented in an ultra-portable, hand held device. Such an approach can support instant detection of the likely presence of one or more SCRA on a broad range of materials.

[0020] Although aspects and embodiments described have particular utility in the detection of SCRAs , the apparatus and methodologies described may be effective in relation to a range of substances of interest, in particular, other drugs of abuse. In particular, the apparatus and methodolology described may be applicable to, for example, some opioids and benzodiazepines, provided their absorption or fluorescence characteristics when irradiated with an appropriately selected excitation source are such that they have a response which overlaps, or aligns with a spectral region in which a physical matrix upon which they may be present does not have a fluorescence response when irradiated with the appropriately selected radiation source.

[0021] It will further be appreciated that the presence of a further range of substances may be detectable using the apparatus and methodologies described herein, for example, other chemical substances which may be absorbed or placed on a physical matrix in order to minimize the chance of detection of that chemical substance. Such chemical substances may, for example, comprise explosive or toxic chemicals. In particular, the apparatus and methodolology described may be applicable to, detection of such substances, provided their absorption or fluorescence characteristics when irradiated with an appropriately selected excitation source are such that they have a fluorescence or absorption response which overlaps, or otherwise aligns, with a spectral region in which a physical matrix upon which they may be present does not have a fluorescence response when irradiated with the appropriately selected radiation source.

[0022] Where reference is made to a phsyical matrix, it is envisaged that such a physical matrix may comprise paper or paper-like material. Such material may comprise a thin sheet made from wood pulp and / or other fibrous substances. The physical matrix may comprise fabric. The fabric may comprise cloth or other material poduced by weaving, knitting or intertwining fibres. The physical matrix may comprise herb-like organic material. The herb-like material may comprise leaf or other organic plant matter. In general, the physical matrix upon which a substance of interest may be placed may comprise a sheet-like or laminar material. The substance of interest may be adsorbed onto a surface of such a material or absorbed into such a material. The apparatus and methodologies described herein are applicable to paper, paper-like matter, fabric matter and herb material. Such material may be organic or man-made.

[0023] The apparatus and methodologies described herein are applicable to those physical matrices for which it can be determined that the physical matrix is substantially spectrally silent in terms of fluorescence response, in a known region when irradiated at a known excitation wavelength. For example, the apparatus and methodologies described herein are applicable to those physical matrices for which it can be determined that the physical matrix is substantially spectrally silent in terms of fluorescence response in around the 325nm to 375nm region when irradiated at an excitation wavelength of around 265nm.

[0024] The apparatus and some methodologies described herein are applicable to those physical matrices for which it can be determined that the physical matrix has one or more known peak in fluorescence response, in a known region when irradiated at a known excitation wavelength. Such one or more peak or feature may be attributable to the presence of an optical brightening agent used on, or forming part of, the physical matrix. For example, the apparatus and some methodologies described herein are applicable to those physical matrices for which it can be determined that the physical matrix has a spectral feature in a fluorescence response comprising at least two intensity peaks in the 400nm to 500nm region when irradiated at an excitation wavelength of around 265nm.

[0025] Accordingly, subject to appropriate selection of factors, including, for example, irradiation wavelength and irradiation bandwidth and appropriate collection of a fluorescence response of a sample exposed to such irradiation, it becomes possible to analyse or assess an indication of the collected fluorescence and, based on such an assessment, determine the likely presence, or otherwise of a substance of interest on a physical matrix.

[0026] According to some embodiments, the physical matrix is selected to be substantially spectrally silent in the 325nm to 375nm region when irradiated at the excitation wavelength.

[0027] According to some embodiments, the excitation wavelength comprises radiation having a bandwidth centred on a wavelength in the 265nm to 300nm region. According to some embodiments, the excitation wavelength has a comprises bandwidth of between 5 and 20nm (FWHM) centred on a wavelength in the 265nm to 300nm region.

[0028] According to some embodiments, the excitation wavelength has a comprises bandwidth of around 12nm (FWHM) centred on a wavelength in the 265nm to 300nm region.

[0029] According to some embodiments, the substance of interest comprises a Synthetic Cannabinoid Receptor Agonist SCRA, an opioid or a benzodiazepine.

[0030] According to some embodiments, the physical matrix comprises at least one of: paper; herb or fabric material.

[0031] According to some embodiments, the substance of interest has a fluorescence response in the 325nm to 375nm region.

[0032] According to some embodiments, the collected emission from the sample comprises fluorescence generatable by a substance of interest on the irradiated sample and emission from the sample at the emission wavelength of the fluorescence response of the substance of interest.

[0033] According to some embodiments, the collected emission comprises a fluorescence emission spectrum collected in the 325nm to 375nm region.

[0034] According to some embodiments, assessing the collected emission comprises: integrating the collected emission across the collected region and comparing the obtained value against a threshold value.

[0035] According to some embodiments, assessing the collected emission comprises: comparing the collected emission against an expected background emission from a sample comprising a physical matrix in the absence of the substance of interest.

[0036] According to some embodiments, the trigger threshold comprises assessing whether the collected emission differs from the expected background emission by a predetermined threshold value. According to some embodiments, the method of assessment further comprises collection of emission at the excitation wavelength, and calculating the expected background emission from a sample comprising a physical matrix in the absence of the substance of interest based upon the emission collected at the excitation wavelength.

[0037] According to some embodiments, the expected background emission is related, correlates to, or is calculatable from, the emission collected at the excitation wavelength via a linear relationship.

[0038] **

[0039] According to some embodiments, the method of assessment further comprises collection of emission when a physical matrix is irradiated by an excitation source, and calculating the expected background emission from a sample comprising a physical matrix in the absence of the substance of interest based upon the emission collected across a wavelength range based upon the excitation source.

[0040] According to some embodiments, the expected background emission is related, correlates to, or is calculatable from, the emission collected at a wavelength associated with the excitation source via a linear relationship.

[0041] According to some embodiments, the expected background emission is related, correlates to, or is calculatable from, the emission collected at a wavelength or wavelength range associated with the excitation source, via a non-linear relationship.

[0042] According to some embodiments, the expected background emission is related, correlates to, or is calculatable from, the emission collected at a wavelength or wavelength range associated with the excitation source via a polynomial relationship.

[0043] According to some embodiments, the expected background emission is related, correlates to, or is calculatable from, the emission collected at a wavelength or wavelength range associated with the excitation source via a complex function.

[0044] According to some embodiments, the expected background emission is related, correlates to, or is calculatable from, a model based upon the emission collected at a wavelength or wavelength range associated with the excitation souce. According to some embodiments, the method of assessment further comprises collection of emission from a physical matrix irradiated by an excitation source, and calculating the expected background emission from a sample comprising a physical matrix in the absence of the substance of interest based upon emission collected at a wavelength or wavelength range associated with, or based upon, a known substance on the physical matrix when irradiated by the excitation source.

[0045] According to some embodiments, the known substance on the physical matrix comprises an optical brightening agent.

[0046] According to some embodiments, the physical matrix comprises a synthetic material. ***

[0047] According to some, but not necessarily all, aspects, there is provided a method of assessing whether a substance of interest having an absorption response at a known wavelength is present on a physical matrix, the method comprising: irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the absorption response of the substance of interest; collection of emission from the sample; assessing the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, triggering a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0048] In some embodiments, the substance of interest has an absorption response at least partially within the visible light region.

[0049] In some embodiments, the substance of interest has an absorption response which overlaps, at least partially, with the region of the physical matrix which is substantially spectrally silent in the 325nm to 375nm region when irradiated at the excitation wavelength.

[0050] In some embodiments, the substance of interest has an absorption response at least partially between 300nm and 400nm.

[0051] In some embodiments, the substance of interest has an absorption response centred around 450nm. In some embodiments, the physical matrix has a spectral feature in a fluorescence response comprising at least two intensity peaks in the 400nm to 500nm region when irradiated at the excitation wavelength.

[0052] In some embodiments, the collected emission comprises an indication of emission intensity collected at each of the two intensity peaks.

[0053] In some embodiments, assessing the collected emission comprises: calculating the ratio of the collected emission at each of the two intensity peaks and comparing the obtained value against a threshold value.

[0054] In some embodiments, the trigger threshold comprises assessing whether the calculated ratio differs from the expected ratio by a predetermined threshold value.

[0055] Some, but not necessarily all, aspects provide a computer program product operable, when executed on a computer, to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the method comprising: receiving an indication of collected emission resulting from irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; assessing the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, triggering a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0056] According to various, but not necessarily all, example embodiments there is provided an apparatus configured to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive an indication of collected emission resulting from irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; and assess the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, trigger a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0057] According to various, but not necessarily all, example embodiments there is provided an apparatus comprising circuitry configured to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the apparatus comprising: circuitry configured to cause the apparatus at least to: receive an indication of collected emission resulting from irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; and assess the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, trigger a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0058] According to various, but not necessarily all, example embodiments there is provided a non-transitory computer-readable medium storing computer program code including instructions that, when executed by a processor, cause a computer to perform a method for assessing whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the method comprising: receiving an indication of collected emission resulting from irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; and assessing the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, triggering a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0059] One aspect provides an apparatus configured to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the apparatus comprising: an irradiation source configured to illuminate a sample comprising the physical matrix at an excitation wavelength, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; at least one emission collection element configured to collect emission from the sample, and a controller configured to assess the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, to trigger an alert indicative of positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0060] An apparatus in accordance with this aspect may be configured to provide an indication of likely presence of a substance of interest on a physical matrix. The substance of interest may comprise a drug of abuse. The substance of interest may comprise a synthetic cannabinoid receptor agonist (SCRA). According to some embodiments, the substance of interest comprises a Synthetic Cannabinoid Receptor Agonist SCRA, an opioid or a benzodiazepine.

[0061] In some embodiments, the apparatus is dimensioned to be handheld. The apparatus may therefore be ultra-portable and easy to use.

[0062] In some embodiments, the apparatus comprises a housing configured to receive a sample to be irradiated. In some embodiments, the apparatus comprises a housing configured to abut a sample to be irradiated. In some embodiments, the apparatus comprises a housing configured to occlude a sample to be irradiated from light from a surrounding environment. The housing may comprise an aperture which may be placed over a sample to be irradiated. In some embodiments, the housing is configured to exclude ambient light from the sample under study.

[0063] In some embodiments, the irradiation source comprises: an LED light source. In some embodiments, the LED light source has an output power of around 50m W. In some embodiments, the LED light source comprises an LED having a narrow bandwidth irradiation profile centred around 265nm. In some embodiments, the irradiation source has a bandwidth (FWHM) of between 10 and 20 nm. In some embodiments, the irradiation source has a (FWHM) bandwidth of around 12nm.

[0064] In some embodiments, the apparatus comprises: a heat sink, configured to transfer heat away from the LED light source.

[0065] In some embodiments, the at least one emission collection element comprises: a bandpass filter corresponding to emission from the sample at the emission wavelength of the fluorescence response of the substance of interest. In some embodiments, the at least one emission collection element comprises: a bandpass filter corresponding to emission from the sample at the known wavelength.

[0066] In some embodiments, the bandpass filter is paired with a photodiode configured to collect emission at a spectral region of interest.

[0067] In some embodiments, the controller comprises: a microprocessor configured to receive and process one or more signal from the at least one emission collection element. In some embodiments, the controller comprises: circuitry or logic configured to receive and process one or more signal from the at least one emission collection element.

[0068] In some embodiments, the controller is configured to assess the collected emission in accordance with assessment steps set out in more detail in the methods described below.

[0069] In some embodiments, the apparatus comprises one or more visual indicator to a user indicative of positive identification of presence of the substance of interest on the sample comprising the physical matrix. The visual indicator may comprise a light source and the colour of the light source may indicate whether the controller has assessed the sample to be such that it is likely to include the substance of interest. The visual indicator may comprise a screen indicating a result.

[0070] In some embodiments, the apparatus comprises one or more audio indicator to a user indicative of positive identification of presence of the substance of interest on the sample comprising the physical matrix.

[0071] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims, as supported by the description.

[0072] Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which:

[0074] Figure 1A illustrates schematically a typical Fluorescence Spectral Fingerprint (FSF) of a typical synthetic cannabinoid receptor agonists (SCRA), in particular, Figure 1A shows the FSF of an SCRA extracted from a seized herbal sample (5F-ADB);

[0075] Figure 1 B illustrates various examples of SCRAs showing the range of ‘core’ moieties;

[0076] Figure 1C shows a collected spectrum of emission of samples which have been irradiated with an excitation source;

[0077] Figure 1 D illustrates graphically the relationship between the intensity peaks of C3 and C4 shown in Figure 1C across a range of studied materials;

[0078] Figure 2A shows example forms of material seized by Avon and Somerset Police (ASP) during the period 2019-2021;

[0079] Figures 2B, 2C and 2D illustrate graphically the spectra obtained from: herb material with nothing present; herb material on which an indole SCRA has been adsorbed; and herb material on which an indazole SCRA has been adsorbed respectively;

[0080] Figures 2E and 2F illustrate graphically the spectra obtained from paper material on which no SCRA is present; and paper material on which an SCRA has been adsorbed respectively;

[0081] Figure 2G illustrates graphically the spectral region C2 showing, for both paper and herb material, an example processed spectra in the presence and absence of an adsorbed SCRA on the physical matrix;

[0082] Figure 2H illustrates an integral of region C2 (-325 - 375 nm) for each of the samples under test;

[0083] Figure 3A is a perspective view of the outside of a device configured to implement approaches and methodologies according to one arrangement;

[0084] Figure 3B comprises a perspective view of main functional components of the device shown in Figure 3A;

[0085] Figure 3C comprises a plan view of main functional components of the device shown in Figures 3A and 3B;

[0086] Figure 4A shows a plot of the value of C1 versus the value of C2 when irradiated with 265nm light as described above for a range of physical matrices;

[0087] Figure 4B illustrates graphically the relationship between the average magnitude of C2 to C2biank and the measured value of C1;

[0088] Figure 5A illustrates graphically a change in relationship of the ratio of C3 to C4 as concentration of OXIZID on a matrix changes; Figure 5B shows the C3:C4 ratio obtained from spectra resulting from emission from 50 pg / cm2of ’tailess’ AM-694, diazepam, etizolam, etonitazene and paracetamol, tramadol and ibuprofen adsorbed onto white paper and irradiated with a 265 nm LED; and

[0089] Figure 5C illustrates schematically the chemical structures of the compounds which formed the basis of the tests illustrated in Figure 5B;

[0090] Figure 5D shows the absorption spectra of the compounds in Figure 5C, providing an indication of a rationale for observed variation in the C3:C4 ratio;

[0091] Figure 6 shows fluorescence spectral data for an example SCRA (MDMB-4en- PINACA) adsorbed onto paper and provided in solution (MeOH) and illustrates observed ‘flattening’ of an excitation spectrum when the example SCRA is adsorbed onto paper;

[0092] Figure 7A shows a plot of the value of C1 versus the value of C2 when irradiated as described above for a range of physical matrices; and

[0093] Figure 7B shows a plot of the value of C2 versus the value of C3 for a range of physical matrices.

[0094] DESCRIPTION OF THE EMBODIMENTS

[0095] Before describing particular arrangements in detail, a general overview is provided.

[0096] OVERVIEW

[0097] Synthetic cannabinoid receptor agonists (SCRAs), also termed ‘spice’ or ‘K2’, are molecules which emulate the effects of the active ingredient of cannabis. SCRA compounds have gained popularity over the last decade. SCRAs are Schedule 1 (USA); Class B (UK) drugs that are highly prevalent in the UK prison system and homeless populations. SCRAs are highly potent, addictive and pose severe health risks to users including psychosis, stroke, epileptic seizures and, in severe cases, fatality. The use of SCRA compounds therefore poses major legal and health concerns since they are often of an unknown strength, are very challenging to detect and are difficult to legislate against.

[0098] SCRAs are chemically diverse, with over a hundred known compounds that have been known to be used as recreational drugs. The chemical diversity of SCRA structures presents a challenge in developing detection modalities. Typically, GC-MS is used for chemical identification, however, this cannot be in place in settings where detection is most critical, for example, in hospital emergency departments, custody suites / prisons, and within homeless communities. A real time, point-of-care method and system to identify the likely presence of SC compounds may help to prevent SCRAs entering custodial environments, direct the care pathway of overdoses in emergency departments and provide information for informed consent in using communities.

[0099] “SPICE” COMPOUNDS

[0100] Synthetic cannabinoid receptor agonists (SCRAs) mimic the effects of tetrahydrocannabinol (THC), which is one of the psychoactive molecules in cannabis. SCRAs bind to cannabinoid receptors in the brain (cannabinoid receptor type 1 and 2; CB1 and CB2) and can act as agonists for receptor function. SCRA compounds may also act on non-CB receptors and may illicit psychoactive or other unwanted effects. SCRA compounds can be highly potent, acting as full agonists of CB receptors, where THC is only a partial agonist. Given their potency, low price and lack of ready detection capability, SCRA compounds are now widely abused and, at present, are Class B drugs in the UK. The potential for overdose with SCRA compounds is very high. SCRA compounds can make users aggressive, induce seizures or stroke and can make users psychotic, exasperating existing mental health conditions.

[0101] The potency of SCRA compounds (for CB agonism) is attributable to a complex interplay of different structural motifs. That is, SCRA compounds with psychoactive properties can be generated through a large combination of four different moieties in combination. SCRA compounds are broadly classified according to the chemical moeity present at a ‘tail’, ‘core’, ‘linker’ and ‘ring’ position. For example, 5-flouro derivatives of the tail position are particularly associated with very small Kd values for both CB1 and CB2, though the precise nature of the moieties at the other positions will also have a significant effect. This structural diversity means there are a large number of SCRA compounds, with the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) recording over 250 different SCRA compounds.

[0102] The primary focus of SCRA detection methods and technologies has been in relation to prosecution of illegal drug use and illegal drug supply. Detecting SCRA compounds is challenging: SCRA compounds cannot typically be identified using standard Cannabis tests, due to their structural diversity. In addition, they tend to be present at relatively low concentrations and are metabolized relatively rapidly. The form of SCRA compounds on sale, typically purchased through the Dark Web, can be sent essentially without trace as a solution absorbed onto paper or other material which can then be sent through the postal system. As an alternative, SCRA compounds can be sprayed onto plant or textile material, making the SCRA product sold to a user more similar to the cannabis it is replacing.

[0103] Detection of SCRA compounds is often achieved via hyphenated mass spectrometry or urine samples which are analysed to detect the presence of SCRA metabolites. NMR represents a much more stringent approach, but is time-consuming and requires input from specialist scientists. Infra-red (IR) spectroscopy represents a potential portable alternative, but detection becomes poor for samples with significant fluorescence emission and where the analyse is adsorbed onto a physical matrix. Immunoassays for SCRA compound detection show promise, but are typically useful for individual SCRA compound detection rather than providing a means to detect the presence of SCRA compounds as a broad group.

[0104] SCRA compounds can be classified in a range of ways, either from Markush structure by defining proscribed moieties at the tail, core, linker and ring positions. One of the overriding common features of the vast majority of SCRA compounds is that a core position is occupied by a functional group which is strongly fluorescent, for example, an indole or indazole. Indeed, the rise of indazole based SCRA compounds is thought to be in response to proscription based on Markush structure. The ‘ring’ position can similarly be occupied by a fluorescent structural motif.

[0105] The fluorescence excitation and emission of indoles / indazoles and related structures (Figure 1 B) is highly sensitive to both the immediate chemical environment but also the immediate solvent environment. For example, it has been demonstrated that a range of substituted indole-3 acetic acids show very significant variation in absorption and fluorescence spectra. Moreover, the spectral properties are further affected by organic / aqueous solvent.

[0106] Indole / indazole and other fluorescent structures may be sensitive to a range of physical factors: (i) the presence of chemical substituents; (ii) the potential for extended delocalized systems to form; (iii) the likelihood of significant resonance energy transfer (RET) between aromatic groups and (iv) the effect of solvent environment (dielectric, pH and so on).

[0107] Nonetheless, despite such sensitivity, arrangements recognise that structurally different SCRA compounds may give rise to sufficiently similar fluorescence responses irrespective of the specific chemical composition at each of the tail, core, linker and ring positions to be of use as a general detection method.

[0108] SCRA DETECTION ON PHYSICAL MATRICES

[0109] The inventors have found that solid matrices, including, for example, paper, fabric and herb material, onto which SCRAs and other substances may be adsorbed for the purposes to introducing them to a user, are spectrally silent in a region -350 nm when the samples are irradiated with a IIV-A light source.

[0110] Figure 1C is an example spectra acquired via excitation of two samples comprising a paper matrix. The samples were excited using a 265nm LED. The samples under study comprise: a paper sample in (i) the presence and (ii) the absence of an SCRA adsorbed onto the paper. In particular, the example spectra of Figure 1C show spectral signatures on white paper in the presence (SP234; MDMB-4en-PINACA) and absence (SP231) of SCRAs. The data on which the spectra of Figure 1C are based was collected via the steps of: direct irradiation of the samples (no pre-processing of the samples); spectral acquisition via fibre optic attached to a spectrometer. Typically, the irradiation occurred by placing the irradiation source -2 cm from the sample surface. Similarly, collection of emission from the sample was performed by placing a tip of the fibre optic approximately -2 cm from the sample. Integration times were -20 seconds.

[0111] Figure 1C shows several regions of the resulting spectra which are of interest. In particular, the regions marked C1 , C2, C3 and C4 of the spectra shown in Figure 1C are of interest as described in more detail below.

[0112] The combined data for the integrated fluorescence intensities in each region for a range of materials (200 samples) is given in Figure 1D and 4A.

[0113] C1 is a peak which corresponds to reflected light from the 265nm LED used to illuminate the sample. The reflected light retains the spectral characteristics of the incident source, including centre wavelength and bandwidth. The magnitude of detected light in this spectral region will vary according to: the intensity of the source; the absorption of the incident light by the sample; and specular reflection by the sample.

[0114] C2 (-325 - 375 nm) corresponds to a spectrally silent region in the absence of an SCRA. This spectral region has a minimal emission response, across the acquired spectrum, when the sample is irradiated in the IIV-A region, such as 265nm. This region is not anticipated to be spectrally silent at all excitation wavelengths. The total emission in this region will be convolved of any background signal (primarily arising from the irradiation source), the quantum yield of any SCRA (if present) determined by concentration and quenching by the matrix material including via FRET to endogenous molecules (see below).

[0115] At concentrations of adsorption on to a matrix of less than -1 mg / cm2, it has been found that the intensity of response attributable to the SCRA concentration is effectively linear. At higher concentrations, it has been found that the signal saturates, as might be anticipated from a classical inner filter effect.

[0116] C3 and C4 (-375-600 nm) correspond to a spectral feature understood to arise from the presence of optical brightening agents (OBAs, for example, stilbenes) included on many physical matrices upon which SCRAs and other substances of interest are adsorbed. The OBAs tend to emit in this specific spectral region in the optical or visible light part of the spectrum. Lignin and cellulose emission has also been reported in a similar spectral region. It is believed that the presence of OBAs on or in a physical matrix can enhance natural fluorescence arising from lignin / cellulosic material. At least for the range of samples studied, it has been found that a large emission band in regions C3 and 04 typically correlates with optically bright materials. Large emission in the region is hardly present, for example, in relation to materials which are not optically bright, such materials include, for example, brown paper or black fabric (Figure 1D).

[0117] In other words, it has been found that materials treated with optical brightening agents are likely to display a similar emission profile to that shown in Figure 10. Materials that are not treated with such optical brightening agents may display diffuse emission bands attributable to endogenous fluorophores or scattering. In practice, it has been found that, for example, brown paper and untreated fabrics have extremely low emission in this spectral region, so as to be effectively spectrally silent (Figure 1D).

[0118] Surprisingly, where there is a significant signal in this spectral region, the ratio of C3 / C4 is almost invariant, regardless of the material type. Figure 1D illustrates graphically the relationship between the intensity peaks of 03 and 04 across a range of studied materials. For the range of materials studied, the C3 / C4 ratio has an average and standard deviation of 1.4 and 0.3, respectively. USING THE OBSERVED EMISSION SPECTRA TO DETECT SCRAs

[0119] The observed characteristics of the spectra of typical physical matrices upon which SCRAs may be adsorbed set out above enables approaches set out in detail below to detect likely presence of, for example, an SCRA, on such physical matrices.

[0120] Matrices including: paper, fabric and herb material, have a region (identified as C2 above) which is substantially spectrally silent in response to irradiation having a wavelength less than around 300nm. Some substances, including, for example, some SCRAs, have a fluorescence response in that spectrally silent region. The inventors hypothesized that detection of a substance, for example, an SCRA, on a matrix could be facilitated by sensitively monitoring emission in the C2 region. In order to sensitively monitor the region, it is necessary to understand what the response of the matrix would be if no additional substance is provided on the matrix. In other words, in order to appreciate the difference made in the C2 region by the presence of an additional substance on the matrix, a “background” response of just the matrix needs to be taken into account.

[0121] The inventors’ hypothesis was tested using seized, suspected SCRA material adsorbed onto different physical matrices. Thirty seized samples of plant material and three samples of paper were extracted into methanol and analysed using a combination of LC-MS, NMR and TLC to understand the extent to which the methodologies of arrangements described below could be applicable to use in the real world. Thin layer chromatography (TLC) was used for initial comparison and as an indication of the number of SCRA compounds present. LC-MS detection in tandem with NMR analysis was invaluable for identifying compounds with virtually indistinguishable mass spectra, e.g. 5F-PB-22 and 5F-MDMB-PICA. The identity of SCRA compounds identified in the samples is reported in Figure 2H. The methods used to analyse the seized samples, so that ground truth data could be used for comparison with the alternative methodology of approaches described herein is set out in the “METHODS” section below.

[0122] Of the samples provided and tested, 6 samples were determined to contain no SCRA. The majority of the herbal material samples contained MDMB-4en-PINACA, which is consistent with European SCRA seizure data in 2020. Having understood what was actually present on the seized samples, it became possible to use methodologies of aspects and embodiments to test the hypothesis of the inventors. The results of methodologies set out herein were compared with detection methods known to return a reliable result.

[0123] Figure 2A shows example forms of material seized by Avon and Somerset Police (ASP) during the period 2019-2021. The Figure shows herb-like ‘street’ material and material on which a substance of interest is soaked / sprayed onto paper. It will be appreciated that the samples which may be of interest can vary significantly in presentation. Samples in the form shown in Figure 2A are often used to achieve illicit entry of banned substances into prisons via the normal postal system.

[0124] To test the hypothesis of the inventors, spectra were obtained in relation to the samples provided by Avon and Somerset Police.

[0125] As described above in relation to Figure 1C, each sample material of interest was irradiated with an excitation source. The excitation source was centred at -265 nm. The excitation wavelength was chosen to prevent spectral overlap of the excitation source into spectral region C2 set out above. The radiation emitted by the samples in the region C2 was collected and studied in more detail. Figures 2B, 2C and 2D illustrate graphically the spectra obtained from: herb material with nothing present; herb material on which an indole SCRA has been adsorbed; and herb material on which an indazole SCRA has been adsorbed respectively. Figures 2E and 2F illustrate graphically the spectra obtained from paper material on which no SCRA is present; and paper material on which an SCRA has been adsorbed respectively.

[0126] Figure 2G illustrates graphically the spectral region C2 showing, for both paper and herb material, an example processed spectra in the presence and absence of an adsorbed SCRA on the physical matrix, where the sample spectra obtained are not subject to pre-test processing.

[0127] Figure 2H illustrates an integral of region C2 (-325 - 375 nm) for each of the samples under test. The coloration reflects the detection for each sample, named in the inset, where ND = nothing detected (no drugs of abuse). It can be seen from Figure 2H that if an SCRA has been adsorbed onto the physical matrix, it is possible to implement a threshold value, indicated by the dashed horizonal line, such that integrating the signal of spectral region C2 (-325 - 375 nm), yields an indication which allows detection of the likely presence of an SCRA on a matrix. That same threshold can be used to indicate whether a sample matrix is such that an SCRA is unlikely to be present on a sample matrix.

[0128] The samples obtained from Avon and Somerset Police were consistent with global trends, where MDMB-4en PINACA is the dominant SCRA detected (~50 % of cases). It should be noted that in two of the samples which would be defined as ‘negative’ samples according to the fluorescence methodology described herein and the threshold indicated in Figure 2H, the full traditional testing method indicated the presence of cannabis (via both GC-MS and NMR). Whilst there are several reports of cannabis giving a measurable fluorescence signal, at least for the excitation wavelengths used here, there appears to be no detectable unusual signal in the region C2 if such cannabis adsorbed samples are subjected to the methods described herein.

[0129] The NMR data suggests the major compounds present in the seized material comprise SCRAs. There were, however, also detectable amounts of other drugs of abuse including: MDMA, heroin, cocaine and cannabis. As we expect from the structures of those drugs of abuse, the data obtained are not convolved of any signal arising from such molecules. Furthermore, no significant quenching effect is expected from the presence of such molecules.

[0130] AN INSTANT, ULTRA-PORTABLE DEVICE WITH DYNAMIC BACKGROUND SCALING.

[0131] The data explained in relation to Figures 2A to 2H indicates that integration of appropriately selected spectral data could provide a mechanism to identify likely presence of an SCRA on complex matrices. In particular, the methodology described in relation to Figures 2A to 2H can be of use to indicate the presence or absence of an SCRA on a physical matrix and does not require significant time-consuming pre -test processing of a herb, paper or material sample.

[0132] The methodology and approaches described above can be implemented as a handheld device capable of substantially instant, real-time testing of samples of interest, including samples seized at a prison or similar.

[0133] One possible device capable of applying the methodologies and approaches described herein utilises high sensitivity detection in each of the spectral regions of interest (C1 , C2, C3 and C4 as set out above and described in relation to Figure 1 C). Figure 3A is a perspective view of the outside of a device configured to implement approaches and methodologies according to one arrangement. Figure 3B comprises a perspective view of main functional components of the device shown in Figure 3A and Figure 3C comprises a plan view of main functional components of the device shown in Figures 3A and 3B.

[0134] The device of Figure 3 comprises a light source for irradiation of a sample. Irradiation is achieved via a high-power 265nm LED 10 with nominal output power of ~50 mW and a FWHM of ~12 nm. The LED 10 is coupled to a heat sink (not shown). The device of Figure 3 further comprises a set of four photodiodes (PDs) 20 each subject to wavelength selection via provision of an appropriate bandpass (BP) filter. The BP filters used in relation to the photodiodes 20 are centred at 265, 350, 420 and 470 with FWHMs of 5, 50, 5 and 5 nm respectively. As a result, those photodiodes collect radiation in the regions C1 to C4 described above in relation to Figure 1C.

[0135] The PDs are amplified and with detection maxima optimized for their respective spectral region of interest. Accordingly, data for each of the regions of an emission spectrum C1 to C4 can be collected via photodiodes 20 and provided by means of an analogue to digital converter (ADC) to a microcontroller (not shown). The collected data is returned as a raw signal in the form of a voltage. The data is appropriately manipulated (described below) and the result of that manipulation by the microcontroller allows a resulting signal to be transformed into a visual report of likely presence or absence of an SCRA on a matrix. In the example device shown in Figure 3, the visual report comprises a change in colour of visual lights provided on a housing of the device (visible in Figure 3A).

[0136] As described previously, SCRAs generally have been found to have an excitation maxima at -290-310 nm (Figure 1A). However, when SCRAs are adsorbed onto paper, the excitation spectrum is significantly flattened compared to an excitation spectrum obtained when an SCRA is dissolved in MeOH, (see Figure 6). As a result there is no particular advantage associated with excitation of samples adsorbed onto a physical matrix at -300-310 nm, which would otherwise cause a large overlapping signal in region C2 of the emission spectrum, namely where it is anticipated that SCRA-related emission is likely to arise.

[0137] The inventors recognised that it is possible to utilize a very high-power (-50 mW) excitation source that is spectrally separate from the emission band of interest, thus achieving the largest emission signal, balanced against the smallest background. Accordingly, the device of Figure 3 comprises an excitation source 10 centred at 265nm, which is the lowest wave-length / highest power LED commercially available at the time of writing.

[0138] Figure 2H indicates that the magnitude of the SCRA signal associated with presence or absence of an SCRA on a sample may vary. Whilst it is possible to apply an empirical threshold (such as the one shown in Figure 2H) based on the observation of a large number of samples and with known backgrounds, such an approach could lead to a number of false negatives and false positives arising from, for example, empirical considerations such as: low concentration of SCRA on a sample; low quantum yield from an SCRA on a sample; and / or high background emission from the physical matrix in which an SCRA may be adsorbed.

[0139] Approaches recognise that ideally, the background signal and the expected magnitude of signal change for an SCRA on any given physical matrix would be known a priori.

[0140] Figure 4A shows a plot of the value of C1 versus the value of C2 when irradiated with 265nm light as described above for a range of physical matrices including: (i) paper comprising a range of coloured paper and including a range of inks provided on that paper comprising printed, crayon, pencil and similar; (ii) fabric comprising: cotton of a a range of colours and textures; and (iii) herb material.

[0141] Figure 4A illustrates that as the magnitude of C1 increases, so C2 increases. The obtained data appears to follow an approximately linear relationship. This relationship is shown as the fitted solid lower line of Figure 4A. In other words, there is a correlative relationship between the magnitude of C1 (the reflected light from the irradiating LED) and C2 (the background arising from the LED and any autofluorescence of the material). That there is such a relationship seems logical, since as a material becomes more absorptive, so the background signal arising from the irradiation will decrease and vice versa.

[0142] However, that the relationship illustrated in Figure 4A follows a consistent trend irrespective of material, provides a means to calculate a predicted background at C2 (C2Pred) from a collected reading of C1. That is, the solid line shown in Figure 4A reflects C2pred. The fitted model shown in Figure 4A gives an average ratio of C2:C2pred = 1.0 and a standard deviation of 0.8. The model based on collected data demonstrates an accurate predictive model for background signal arising in the spectral region where SCRA fluorescence emission could be detected.

[0143] Having assessed data for untreated materials and formulated an appropriate model for predicting background emission in the region C2, the inventors investigated the way in which the signal of C2 varied for a range of SCRAs, at similar concentrations, on a range of different matrices.

[0144] It is known that the quantum yield of different SCRAS will vary. The inventors therefore investigated the ratio of a measured magnitude of C2 to C2biank, where C2biank is the matrix with no SCRA added. A value above 1 is attributable to the presence of an SCRA. Figure 4B illustrates graphically the relationship between the average magnitude of C2 to C2biank and the measured value of C1 for a range of SCRAs on different paper types. The matrices include a range of white and brown papers (5 in total for each of 5 SCRAs; MDMB-4en-PINACA, ADB-P7AICA, MMB-CHMICA, MDMB- 4en-PICA and 5F-AKB-48. Figure 4B shows that there is an increase in the ratio of the SCRA related signal for the same molecules as the magnitude of C1 increases. That is, as the absorption of light via the material increases, so the magnitude of the fluorescence signal attributable to the same SCRA concentration increases. That trend can be modelled as a simple linear function shown as a fitted line in Figure 4B.

[0145] The relationships illustrated in Figure 4A and 4B provide that there is a quantifiable relationship relating the magnitude of C1 and C2 allowing prediction of a background signal associated with just a physical matrix the region C2 using a simple function. Furthermore, for the same SCRA concentration, a signal at C2 increases with the magnitude of C1 in accordance with a simple mathematical function.

[0146] Combining the two functions provides a numerical model for the detection of SCRAs on a huge range of diverse background materials and that model is scalable according to likely concentration of SCRA.

[0147] The resulting numerical model is shown as the upper solid line in Figure 4A. Signals detected in the region C2 which fall above this line can be termed a ‘positive’ for the likely presence of an SCRA on a physical matrix.

[0148] The model and resulting curve can be scaled to remove false positives with a concomitant decrease in concentration sensitivity. Without any such scaling, the model illustrated in Figure 4A gives rise to a false positive rate of ~5 %, with a detection limit of ~50 pg cm-2.

[0149] Studies have placed the lower limit of ‘real’ SCRA concentrations on physical matrices at ~50 pg cm-2and so the model set out in Figure 4A balances detection sensitivity and false positive rate adequately for real-life samples.

[0150] ***

[0151] Figure 7A shows a plot of the value of C1 versus the value of C2 when irradiated as described above for a range of physical matrices.

[0152] The relationship between C1 and C2 can be modelled with a function that is more complex than a simple linear function (See, for example, Equation 1 set out below).

[0153] The dashed black line represents a complex polynomial that provides an accurate model of the vast majority of samples (light grey data points). The solid line reflects a multiple of the model (set out in Equation 1) which can be used to provide a threshold value, at or above which a substance of interest is considered to be present. The darker data points shown in Figure 7A represent entirely synthetic fabrics.

[0154] It can be seen that the C2 data can, in some examples, be more accurately predicted using models that are not linear and that use of a more complex, non-linear, model may have advantages.

[0155] The data shown in Figure 7A shows a complex polynomial function (black dashed line in Figure 7A) can be used to accurately model the data and provide a threshold prediction model:

[0156] C2 = A^l2+ A2C1A+ A4

[0157] [Equation 1]

[0158] Where:

[0159] C1 is the signal at channel 1 and C2 is the signal at channel 2.

[0160] And A represents appropriately selected coefficients. The model linking C2 and C1 can, in some implementations, be tuned to provide a threshold model at which the detection is triggered. That tuning may, for example, comprise a simple multiplier of for example, the model set out in Equation 1. Such a threshold model is shown as the solid line of Figure 7 A.

[0161] It can be seen from Figure 7A that synthetic fabrics, including polyester, polyacrylamide, nylon, polyurethane and related synthetics may not track well with some models and therefore a physical matrix which comprises a synthetic material may result in a false positive. It can also be seen from Figure 7A that the data from a synthetic physical matrix tends to track within a relatively narrow range of C1 values.

[0162] Figure 7B shows a plot of the value of C2 versus the value of C3 for a range of physical matrices. It can be seen that the C2 value from the synthetic materials (within the restricted range of C1 values) can be modelled by a relationship between C2 and C3 as shown in Figure 7B. The data can be modelled via function such as the form of a log normal distribution function (solid line of Figure 7B) as set out in Equation 2

[0163] [Equation 2]

[0164] Where:

[0165] C3 is the signal at channel 3

[0166] Ai is a baseline offset

[0167] A2 is the area under the curve w is the log standard deviation; and xcis the centre of the peak function.

[0168] As described in relation to Figure 7A, a similar detection threshold can be tuned using a multiplier of the model, for example as set out in Equation 2. Such an approach addresses the potential for false positives arising from using C1 as the predictor of C2 for some materials and may leads to an overall improvement (reduction) in false positive rate across a range of different material types.

[0169] C3 represents one of the limbs of putative Optical Brightening Agent (OBA) peaks as described in more detail below. In other words, data shown in Figure 7A and 7B suggests that information relating to the intensity of emission arising from the OBAs can be used, in some specific cases, as a predictor of background C2 value. That information may have particular utility in relation to synthetic materials.

[0170] The device shown in Figure 3 has been used to collect results in relation to the seized material described above in relation to Figure 2 (both herb and paper material). The device of Figure 3 configured to implement methodologies in accordance with described approaches is able to detect the presence of SCRAs in all of the samples qualified by NMR to have SCRA present without giving false positives from the presence of other drugs including cannabis, cocaine, and other drugs of abuse.

[0171] To test the detection limit of the device shown in Figure 3, the inventors investigated a range of concentrations of different SCRAs, adsorbed onto different physical matrices. Results indicate a detection concentration with a lower limit of ~50 pg cm'2for the SCRAs tested, across the range of materials tested. The materials tested included: paper (white, brown, blue, pink, printed and unprinted); fabric (cotton and synthetic at a range of colours and thicknesses); herb material (as described above); in vape liquid spotted onto filter paper (range of ‘flavours’ and brands ).

[0172] The inventors conducted a blind trial of a large number of paper samples seized from prisons (175 samples in the form of letters, cards and similar). The presence of SCRAs and other molecules of interest were established via GC-MS. The data obtained via the blind trial indicated that the device of Figure 3 has a sensitivity of 81% and a specificity of 82%. It will be appreciated that the detection sensitivity of the device will be less than GC-MS. The thresholding associated with a detection event implemented by a device such as the example sown in Figure 3 can be increased to decrease false positives as desired. The blind trial data therefore points to an extremely effective tool in rapid screening of material for the presumptive presence of SCRAs.

[0173] DETECTION OF NON-FLUORESCENT MOLECULES ON PHYSICAL MATRICES A small subset of SCRAs (OXIZIDs) have a relative quantum yield much lower than for the majority of other SCRAs. Unlike other SCRAs, these SCRAs are highly absorptive in the visible region, with maxima at -350 nm. Given the overlap of the absorption maximum and spectral regions C3 and C4 (Figure 1 C), the inventors considered whether the presence of such SCRA molecules might affect the magnitude of, for example, C4 via fluorescence resonance transfer (FRET) or a similar mechanism.

[0174] Further, since the inventors had observed that the C3 / C4 ratio is so highly conserved amongst a broad range of materials (Figure 1 D), the inventors hypothesized that variation in the C3 / C4 ratio may act as a proxy detection method indicative of the presence of such OXIZIDs on a physical matrix.

[0175] Figure 5A illustrates graphically a change in relationship of the ratio of C3 to C4 as concentration of OXIZID on a matrix changes. Figure 5A shows that as the concentration of three different OXIZIDs (MDA-19, BZO-POXIZID and 5F-BZO- POXIZID is increased on a physical matrix comprising white paper, there is a decrease in the C3 / C4 ratio. Based on the values determined from the data shown in Figure 1 D, use of the C3 / C4 ratio as predictive indicator of the presence of an OXIZID on a matrix, has a useful lower bound of sensitivity at ~50 pg cm'2. It is interesting to note that even where other absorptive compounds in similar spectral regions are added to paper (for example: printed / pen ink; Figurel D), there is no similar shift in the C3 / C4 ratio. The inventors believe that the shift in the C3 / C4 ratio is non-specific, arising from, for example, FRET or another photophysical mechanism driven by the absorption of the analyte.

[0176] Accordingly, the inventors hypothesized that other aromatic moieties, adsorbed onto paper, might be detectable in a similar way. Figure 5B shows the C3:C4 ratio obtained from spectra resulting from emission from 50 pg / cm2of a ‘tailess’ mimic of AM-694 (2- Cl MeOH), diazepam, etizolam, etonitazene, ibuprofen, paracetamol and tramadol adsorbed onto white paper and irradiated with a 265 nm LED as described above.

[0177] Figure 5B shows the same decrease in C3 / C4 ratio for benzodiazepines and opioids, as is observed in relation to OXIZIDs. However, the ibuprofen, paracetamol and tramadol showed no change in the C3 / C4 ratio.

[0178] Figure 5C illustrates schematically the chemical structures of the compounds which formed the basis of the tests illustrated in Figure 5B. The combination of Figure 5B and 5C suggests a requirement for affecting the C3 / C4 ratio is an extended cross conjugated system; a simple benzene ring is insufficient. Figure 5D shows the absorption spectrum of such compounds, illustrating the requirement for a significant absorption feature in the -350 nm region to afffect the C3 / C4 value.

[0179] Nonetheless, it will be appreciated that the detection methodology described herein, as implementable by a device such as that shown in Figure 3 may be capable of detecting the likely presence of SCRAs, and other illicit substances adsorbed onto physical matrices including: paper and fabric, without false positives arising from generic aromatic (benzene) moieties.

[0180] APPLICABILITY OF METHODOLOGIES AND APPARATUS IN ACCORDANCE WITH ARRANGEMENTS

[0181] Below is a list of substances of interest which have been demonstrated to be detectable by use of the methodologies described. In other words, arrangements are can be applied to substances including but not limited to:

[0182]

[0183] In relation to methodologies which utilise features of optical brightening agents, and particularly the ratio of such features, to detect likely presence of a substance of interest, those substances of interest include: all the benzodiazepines, Zopiclone and Etonitazene.

[0184] In relation to methodologies which utilise features of optical brightening agents, and particularly the ratio of such features, to detect likely presence of a substance of interest, where the substance of interest is an SCRA, the SCRAs detectable using such a method includes: MDA-19, BZO-POXIZID, 5F-BZO-POXIZID and 5F-PB-22.

[0185] SUMMARY

[0186] The majority of physical matrices of interest including: paper; fabric; and organic herb materials give a consistent emission spectrum when excited with a UV source (265 nm). In particular, such materials have an optically silent region. Many SCRAs emit in that optically silent region.

[0187] The magnitude of the background in this region can be predicted with a high degree of accuracy based on the magnitude of reflected excitation light alone. This enables assignment of a material-only based emission based on the absorption of the irradiation light.

[0188] Emission arising from putative OBA fluorescence is substantially consistent. Variation of that emission can be used to detect the presence of generic absorptive compounds.

[0189] METHODS

[0190] The seized samples were analysed according to the methodologies set out below: SAMPLE PREPARATION

[0191] 100 mg of plant material was extracted into 2 mL of methanol. The mixture was sonicated for 30 mins in a water bath (25 °C) and then centrifuged for 1 hour at 13300 rpm to remove solids. Filtrate was collected and pellet discarded.

[0192] THIN LAYER CHROMATOGRAPHY (TLC)

[0193] Each sample extract was spotted onto a wide TLC plate. The TLC was repeated for two solvent systems: hexane:diethyl ether, 2:1 ; toluene:ditheyl ether, 9:1. TLC spots were compared against the other samples for potential matches.

[0194] NUCLEAR MAGNETIC RESONANCE (NMR)

[0195] Using the assumption that the concentration of SCRA in each sample is approximately 1 - 30 mg / g plant material, the assumption was made that there is approximately 1 mg SCRA in 1 mL of methanol extract. The methanol was removed under reduced pressure and the sample was redispersed in the chosen NMR solvent. NMR spectra were recorded on a 500 MHz Agilent ProPulse with a 96-position sample changer. 1 H and 13C NMR data were determined at 500 MHz in either CDCI3, DMSO-d6 and CD3OD unless otherwise specified, and chemical shifts are reported downfield from TMS. Coupling constants, J, are reported in Hz. Spectra were compared to SCRA NMR data in literature.

[0196] CHROMATOGRAPHIC SEPARATION AND DETECTION (LC-MS).

[0197] LC-MS analyses were performed using an Agilent QTOF 6545 with Jetstream ESI spray source coupled to an Agilent 1260 Infinity II Quat pump HPLC with 1260 autosampler, column oven compartment and variable wavelength detector (VWD). The MS was operated in separate injections in either positive or negative ionization mode with the gas temperature at 250°C, the drying gas at 11 L / min and the nebulizer gas at 35 psi (2.41 bar). The sheath gas temperature and flow were set to 300°C and 12 L / min, respectively. The MS was calibrated using reference calibrant introduced from the independent ESI reference sprayer. The VCap, Fragmentor and Skimmer was set to 3500, 160 and 45 V respectively. The MS was operated in all-ions mode with 3 collision energy scan segments at 0, 20 and 40 eV. Chromatographic separation of a 5 pL sample injection was per-formed on a InfinityLab Poroshell 120 EC-C18 (3.0 x 50 mm, 2.7 pm) column using H20 (Merck, LC-MS grade) with 0.1 % formic acid (FA, Fluka) v / v and acetonitrile (ACN, SigmaAldrich) with 0.1 % FA v / v as mobile phase A and B, respectively. The column was operated at flow rate of 0.5 mL / min at 50°C starting with 30 % mobile phase B, as follows;

[0198] The VWD was set to detect at 254 and 320 nm wavelengths at a frequency of 2.5 Hz. Data processing was automated in Qual 10 with molecular feature extraction set to the largest 20 compounds for [M+H]+, [M-H]- and [M+HCOO]- ions. The results were also searched against a NPS database (containing 1110 compound entries) with a forward score of 25 and reverse score of 70, and mass tolerances within 5 ppm of the reference library matches. Qualified ions had co-elution scores of > 90, retention time tolerances of ± 0.10 and a minimum S / N of > 5.00.

[0199] Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

Claims

CLAIMS1. A method of assessing whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the method comprising: irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; collection of emission from the sample assessing the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, triggering a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

2. A method according to claim 1, wherein the physical matrix is substantially spectrally silent in the 325nm to 375nm region when irradiated at the excitation wavelength.

3. A method according to claim 1 or claim 2, wherein the excitation wavelength comprises radiation having a bandwidth centred on a wavelength in the 265nm to 300nm region.

4. A method according to any preceding claim, wherein the substance of interest comprises a Synthetic Cannabinoid Receptor Agonist SCRA, an opioid or a benzodiazepine.

5. A method according to any preceding claim, wherein the physical matrix comprises at least one of: paper; herb or fabric material.

6. A method according to any preceding claim, wherein the substance of interest has a fluorescence response in the 325nm to 375nm region.

7. A method according to any preceding claim, wherein the collected emission from the sample comprises fluorescence generatable by a substance of interest on the irradiated sample and emission from the sample at the emission wavelength of the fluorescence response of the substance of interest.

8. A method according to any preceding claim, wherein the collected emission comprises an emission spectrum collected in the 325nm to 375nm region.

9. A method according to any preceding claim, wherein assessing the collected emission comprises: integrating the collected emission across the collected region and comparing the obtained value against a threshold value.

10. A method according to any one of claims 1 to 9, wherein assessing the collected emission comprises: comparing the collected emission against an expected background emission from a sample comprising a physical matrix in the absence of the substance of interest.

11. A method according to any preceding claim, wherein the trigger threshold comprises assessing whether the collected emission differs from expected background emission by a predetermined threshold value.

12. A method according to any preceding claim, wherein the method comprises collection of emission at the excitation wavelength, and calculating expected background emission from a sample comprising a physical matrix in the absence of the substance of interest based upon the emission collected at the excitation wavelength.

13. A method according to claim 12, wherein the expected background emission is related to the emission collected at the excitation wavelength via a linear relationship.

14. A method according to any one of claims 1 to 6, wherein the substance of interest has an absorption response at least partially within the visible light region.

15. A method according to any one of claims 1 to 6, wherein the substance of interest has an absorption response at least partially between 300nm and 400nm.

16. A method according to any one of claims 1 to 6, wherein the substance of interest has an absorption response which overlaps, at least partially with the region of the physical matrix which is substantially spectrally silent in the 325nm to 375nm region when irradiated at the excitation wavelength.

17. A method according to any one of claims 14 to 16, wherein the physical matrix has a spectral feature in a fluorescence response comprising at least two intensity peaks in the 400nm to 500nm region when irradiated at the excitation wavelength.

18. A method according to claim 17, wherein the collected emission comprises an emission intensity collected at each of the two intensity peaks.

19. A method according to claim 17 or claim 18, wherein assessing the collected emission comprises: calculating the ratio of the collected emission at each of the two intensity peaks and comparing the obtained value against a threshold value.

20. A method according to claim 19, wherein the trigger threshold comprises assessing whether the calculated ratio differs from the expected ratio by a predetermined threshold value.

21. A computer program product operable, when executed on a computer to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the method comprising: receiving an indication of collected emission resulting from irradiation at an excitation wavelength of a sample comprising the physical matrix, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; assessing the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, triggering a positive identification of presence of the substance of interest on the sample comprising the physical matrix.

22. Apparatus configured to assess whether a substance of interest having a fluorescence or absorption response at a known wavelength is present on a physical matrix, the apparatus comprising: an irradiation source configured to illuminate a sample comprising the physical matrix at an excitation wavelength, the excitation wavelength being selected to be distinct from the known wavelength of the fluorescence or absorption response of the substance of interest; at least one emission collection element configured to collect emission from the sample, anda controller configured to assess the collected emission to determine whether the collected emission meets a predetermined trigger threshold and, if so, to trigger an alert indicative of positive identification of presence of the substance of interest on the sample comprising the physical matrix.

23. Apparatus according to claim 22, wherein the apparatus comprises: a housing configured to receive a sample to be irradiated, and the housing is configured to exclude ambient light from the sample under study.

24. Apparatus according to claim 22 or claim 23, wherein the irradiation source comprises: an LED light source, having a narrow bandwidth irradiation profile centred around 265nm.

25. Apparatus according to any one of claims 22 to 24, wherein the at least one emission collection element comprises: a bandpass filter corresponding to emission from the sample at the emission wavelength of the fluorescence response of the substance of interest.

26. Apparatus according to any one of claims 22 to 25, wherein the at least one emission collection element comprises: a bandpass filter corresponding to one or more emission feature associated with presence of an optical brightening agent on the physical matrix.

27. Apparatus according to claim 25 or claim 26 wherein the bandpass filter is paired with a photodiode configured to collect emission at a spectral region of interest.

28. Apparatus according to any one of claims 22 to 27, wherein the controller comprises: a microprocessor configured to receive and process one or more signal from the at least one emission collection element.

29. Apparatus according to any one of claims 22 to 27, wherein the substance of interest comprises a Synthetic Cannabinoid Receptor Agonist SCRA, an opioid or a benzodiazepine.

30. Apparatus to any one of claims 22 to 29, wherein the controller is configured to assess the collected emission in accordance with assessment steps set out in any one of claims 1 to 20.

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