Drug detection

Abstract

Aspects and embodiments relate to apparatus and methods to identify whether a drug is present in a provided sample. One aspect provides a drug detection method to identify whether a drug is present in a provided sample, the method comprising: determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample. Aspects recognise that the rapid detection of certain drugs can be enhanced by augmenting a fluorescence spectral fingerprint based detection methodology with photochemical reactivity tracking. The hybrid photochemical fingerprinting methodology in accordance with aspects allows for capture of information on both: new fluorescent species that emerge as a result of a specifically induced photochemical reaction(s) notable detectable drugs, but also the loss of fluorescent / absorptive species as they are photochemically degraded. Both such physical changes are reflective of the specific chemistry of the analyte (drug) which is being tested for.

Description

[0001] DRUG DETECTION

[0002] TECHNOLOGICAL FIELD

[0003] Various example embodiments relate to apparatus and methods to identify whether a drug is present in a provided sample.

[0004] BACKGROUND

[0005] Illicit substance use, for example, illicit use of various controlled substances, drugs and / or medications, is prevalent across Europe and the rest of the world. It is imperative that drug detection methods adapt to meet the challenge of increased substance use and abuse.

[0006] Various substance detection methods are known. For example, a variety of drug testing methods are available including: screening, colorimetric detection, immunochemical assays, and chromatographic methods. Whilst there are advantages and disadvantages to each method, colorimetric detection is typically favoured in a point of care setting due to being both rapid and portable. However, colorimetric detection tends to be specific to individual structures. In contrast, chromatographic methods including Liquid Chromatography Mass Spectroscopy (LC-MS) and Mass Spectroscopy (MS) provide a more advanced detection method capable of resolving a large range of compounds, with a low limit of detection. However, the high associated costs and lack of portability renders chromatographic methods generally unsuitable for mobile drug testing.

[0007] It is desirable to enhance sensitivity and / or discriminatory ability of substance detection approaches, for example, to accelerate delivery of a point-of-care technology which can be used confidently by a range of stakeholders; from medical to prison staff.

[0008] BRIEF SUMMARY

[0009] The scope of protection sought for various example embodiments of the invention is set out in the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0010] It has been shown that hybrid photochemical fingerprinting, according to which a fluorescence spectral fingerprint (FSF) of a solution containing a synthetic cannabinoid receptor agonist (SCRA) of interest is obtained, before that solution is irradiated to induce a photochemical change, and a second fluorescence spectral fingerprint (FSF) of a solution containing a synthetic cannabinoid receptor agonist (SCRA) of interest is obtained, can be used to provide a rapid assessment of SCRA presence in the solution.

[0011] Full details of such an approach can be found in “Photochemical Fingerprinting is a Sensitive Probe for the Detection of Synthetic Cannabinoid Receptor Agonists; toward Robust Point-of-Care Detection” Andrews et al, Anal Chem, 2023, 95, 703-713, https: / / doi.org / 10.1021 / acs.analchem.2c02529. [1]

[0012] Aspects recognise that such an approach may be extended and used as a mechanism for detection of substances other than SCRAs.

[0013] According to various, but not necessarily all, example embodiments there is provided: a drug detection method to identify whether a drug is present in a provided sample, the method comprising: determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; determining a wavelength for irradiation of the provided sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample.

[0014] Described aspects recognise that the rapid detection of certain drugs can be enhanced by augmenting a fluorescence spectral fingerprint based detection methodology with photochemical reactivity tracking. The hybrid photochemical fingerprinting methodology in accordance with aspects allows for capture of information on both: new fluorescent species that emerge as a result of a specifically induced photochemical reaction(s) notable detectable drugs, but also the loss of fluorescent / absorptive species as they are photochemically degraded. Both such physical changes are reflective of the specific chemistry of the analyte (drug) which is being tested for.

[0015] According to some embodiments, determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: determining a wavelength of an absorption maxima of the provided sample and irradiating the provided sample with irradiation having a wavelength close to the determined absorption maxima to induce a photochemical change in the provided sample.

[0016] According to some embodiments, determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: measuring an absorption spectrum of a plurality of drugs and evaluating the measured absorption spectra to select one or more wavelength for irradiation of the provided sample.

[0017] According to some embodiments, the wavelength for irradiation comprises a wavelength in the ultraviolet region of the spectrum.

[0018] According to some embodiments, the wavelength for irradiation of the provided sample may comprise a wavelength, or plurality of wavelengths, in the range from around 230nm to around 400nm. According to some embodiments, the wavelength for irradiation may comprise a range of wavelengths. The rage of wavelengths may comprise, for example, a range of UV wavelengths. Evaluation of irradiation wavelength may comprise selecting a range of UV wavelengths with which to irradiate a sample, that irradiation may be performed in a non-provided-sample-specific manner, such that a provided sample is irradiated, for example, with broadband UV, or a cycle of different UV wavelengths. According to some embodiments, the drug comprises at least one of the following: a photochemically active aromatic molecule; or a molecule which photochemically changes to form an aromatic molecule; or a synthetic cannabinoid receptor agonist; or a cannabinoid; or an opioid; or a benzodiazepine; or a cathinone; or a steroid or a sedative.

[0019] According to some embodiments, the provided sample comprises: a drug in solution, and optionally the provided sample comprises at least one of the following: a drug in ethanol solution; or a drug in saliva; or a combusted drug in saliva; or a drug in solid form.

[0020] According to some embodiments, the provided sample comprises: a drug adsorbed onto a physical matrix, and optionally wherein the physical matrix comprises paper.

[0021] According to some embodiments, triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a first and second fluorescence spectral matrix which both match said determined first and second fluorescence spectral matrix associated with the provided sample within the threshold.

[0022] According to some embodiments, triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a difference map between a first and second fluorescence spectral matrix which matches a difference map created by comparison of the determined first and second fluorescence spectral matrix associated with the provided sample within the threshold.

[0023] According to some embodiments, triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a difference map between a first and second fluorescence spectral matrix which matches a difference map created by comparison of the determined first and second fluorescence spectral matrix associated with the provided sample, and a first fluorescence spectral matrix which matches a determined first fluorescence spectral matrix associated with the provided sample within the threshold.

[0024] According to some embodiments, irradiating the provided sample comprises irradiating the provided sample for a predetermined time period at a selected intensity and optionally wherein the predetermined time period and intensity are selected to be likely to induce a photochemical change in a drug in the provided sample.

[0025] According to some, but not necessarily all, aspects there is provided a drug detection apparatus configured to identify whether a drug is present in a provided sample, the apparatus comprising: a controller, an excitation source and an emission detector; the controller comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the controller at least to perform: determining a first fluorescence spectral matrix associated with the provided sample by: causing excitation of the provided sample by the excitation source at a first excitation wavelength; and receiving, from the emission detector, a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; storing excitation and emission data obtained in each excitation and receiving step; and communicating with the stored data to create the first fluorescence spectral matrix associated with the provided sample; determining a wavelength for irradiation of the provided sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; determining a second fluorescence spectral matrix associated with the provided sample by: causing excitation of the provided sample by the excitation source at a first excitation wavelength; and receiving, from the emission detector, a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; storing excitation and emission data obtained in each excitation and receiving step; and communicating with the stored data to create the second fluorescence spectral matrix associated with the provided sample; comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample.

[0026] According to some embodiments, determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: determining a wavelength of an absorption maxima of the provided sample and irradiating the provided sample with irradiation having a wavelength close to the determined absorption maxima to induce a photochemical change in the provided sample.

[0027] According to some embodiments, determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: measuring an absorption spectrum of a plurality of drugs and evaluating the measured absorption spectra to select one or more wavelength for irradiation of the provided sample.

[0028] According to some embodiments, the wavelength for irradiation comprises a wavelength in the ultraviolet region of the spectrum.

[0029] According to some embodiments, the wavelength for irradiation of the provided sample may comprise a wavelength, or plurality of wavelengths, in the range from around 230nm to around 400nm. According to some embodiments, the wavelength for irradiation may comprise a range of wavelengths. The rage of wavelengths may comprise, for example, a range of UV wavelengths. Evaluation of irradiation wavelength may comprise selecting a range of UV wavelengths with which to irradiate a sample, that irradiation may be performed in a non-provided-sample-specific manner, such that a provided sample is irradiated, for example, with broadband UV, or a cycle of different UV wavelengths.

[0030] According to some embodiments, the drug comprises at least one of the following: a photochemically active aromatic molecule; or a molecule which photochemically changes to form an aromatic molecule; or a synthetic cannabinoid receptor agonist; or a cannabinoid; or an opioid; or a benzodiazepine; or a cathinone; or a steroid or a sedative.

[0031] According to some embodiments, the provided sample comprises: a drug in solution, and optionally the provided sample comprises at least one of the following: a drug in ethanol solution; or a drug in saliva; or a combusted drug in saliva; or a drug in solid form.

[0032] According to some embodiments, the provided sample comprises: a drug adsorbed onto a physical matrix, and optionally wherein the physical matrix comprises paper.

[0033] According to some embodiments, triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a first and second fluorescence spectral matrix which both match said determined first and second fluorescence spectral matrix associated with the provided sample within the threshold.

[0034] According to some embodiments, triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a difference map between a first and second fluorescence spectral matrix which matches a difference map created by comparison of the determined first and second fluorescence spectral matrix associated with the provided sample within the threshold.

[0035] According to some embodiments, triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a difference map between a first and second fluorescence spectral matrix which matches a difference map created by comparison of the determined first and second fluorescence spectral matrix associated with the provided sample, and a first fluorescence spectral matrix which matches a determined first fluorescence spectral matrix associated with the provided sample within the threshold.

[0036] According to some embodiments, irradiating the provided sample comprises irradiating the provided sample for a predetermined time period at a selected intensity and optionally wherein the predetermined time period and intensity are selected to be likely to induce a photochemical change in a drug in the provided sample.

[0037] According to some embodiments, the excitation source comprises: an array of different LEDs selected to have an emission spectrum which, when taken together, spans a wavelength range from 250nm to 400nm. According to some embodiments, the controller is configured to control said array of different LEDs to selectively switch one or more LEDs in said array on or off and thereby control said first wavelength.

[0038] According to some embodiments, the emission detector comprises a monochromated spectrometer.

[0039] According to some embodiments, the library is stored on locally provided memory; and optionally wherein the apparatus comprises communication circuitry configured to communicate with a remotely stored library.

[0040] According to some, but not necessarily all, aspects, there is provided an apparatus for drug detection configured to identify whether a drug is present in a provided sample, the apparatus comprising: circuitry configured to perform determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; circuitry configured to perform determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; circuitry configured to perform determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; circuitry configured to perform comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, circuitry configured to perform triggering a positive identification of a drug in the provided sample. The circuitry may be configured perform the optional features set out in relation to the apparatus mentioned above.

[0041] According to some, but not necessarily all, aspects, there is provided an apparatus for drug detection configured to identify whether a drug is present in a provided sample, the apparatus comprising: means configured to perform determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; means configured to perform determining a wavelength for irradiation of the provided sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; means configured to perform determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; means configured to perform comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, circuitry configured to perform triggering a positive identification of a drug in the provided sample.

[0042] The means may be configured perform the optional features set out in relation to the apparatus mentioned above.

[0043] According to some, but not necessarily all, aspects there is provided: a non-transitory computer readable medium comprising program instructions stored thereon for performing a drug detection method to identify whether a drug is present in a provided sample, the instructions comprising at least the following: determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; determining a wavelength for irradiation of the provided sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample.

[0044] The instructions may be for performing the optional features set out in relation to the method mentioned above.

[0045] According to some, but not necessarily all, aspects there may be provided a computer program product operable, when executed on a computer, to perform the method referred to above. The computer program product may be operable, when executed on a computer, to perform the optional features set out in relation to the method mentioned above.

[0046] 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.

[0047] 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.

[0048] BRIEF DESCRIPTION

[0049] Some example embodiments will now be described with reference to the accompanying drawings in which:

[0050] FIG. N1A to N1E illustrate various aspects of an apparatus configured to perform a hybrid photochemical fingerprinting method;

[0051] FIG. N2A to N2C show graphically the emission spectra of CBD, THC and a combination irradiated over time with a 265nm irradiation source to induce a photochemical change;

[0052] FIG. N3 shows fluorescence spectral fingerprints (FSFs) obtained pre- and postirradiation to induce a photochemical change, together with a difference map comparison between the FSFs for 6 different molecules (Flunitrazepam, Fentanyl, Mephedrone, Etonitizene, Dihydrocodiene and CDMT in each column left to right) tested in an ethanol solution;

[0053] FIG. N4 shows fluorescence spectral fingerprints (FSFs) obtained pre- and postirradiation to induce a photochemical change, together with a difference map comparison between the FSFs for 5 different molecules (Clonazepam, Diazepam, Alprazolam, Etizolam, and Xylazine in each column left to right) tested in an ethanol solution;

[0054] FIG. N5A shows fluorescence spectral fingerprints (FSFs) obtained pre- and postirradiation to induce a photochemical change, together with a difference map comparison between the FSFs for 4 different cases: no drug adsorbed onto a paper matrix; a synthetic cannabinoid adsorbed onto a paper matrix; a Benzodiazepine adsorbed onto a paper matrix; and a Nitazene adsorbed into a paper matrix. Each row relates to one case;

[0055] FIG. N5B shows a photograph of samples on paper after irradiation to induce a photochemical change;

[0056] FIG. N6 illustrates schematically some components of an apparatus according to some arrangements; and

[0057] FIG. N7 illustrates schematically steps of methods performed in accordance with some arrangements. DETAILED DESCRIPTION

[0058] Before discussing the example embodiments in any more detail, first an overview will be provided.

[0059] Drug Detection

[0060] Point-of-care drug testing is an important modality to support users. Advantageously, detection methods for point-of-care drug testing are both fast and portable. A variety of drug testing methods are available including: screening, colorimetric detection, immunochemical assays, and chromatographic methods. Whilst there are advantages and disadvantages to each method, colorimetric detection is typically favoured in a point of care setting due to being both rapid and portable. However, colorimetric detection tends to be specific to individual structures. In contrast, chromatographic methods including Liquid Chromatography Mass Spectroscopy (LC-MS) and Mass Spectroscopy (MS) provide a more advanced detection method capable of resolving a large range of compounds, with a low limit of detection. However, the high associated costs and lack of portability renders chromatographic methods generally unsuitable for mobile drug testing.

[0061] Fluorescence Spectral Fingerprinting (FSF)

[0062] It has been demonstrated that fluorescence spectral fingerprinting (FSF) has potential as a rapid point-of-care test for SCRAs [2], FSF may be used, for example, as a probe of SCRA use. It has been shown that common SCRA compounds, in both pure samples and in oral fluid (saliva), produce individual FSFs, with a possibility to extract information about the structure and concentration of these substances from the FSF [2], It has been suggested that part of the sensitivity of SCRA FSFs to different, structurally similar, molecules may arise from differences in cross conjugation and associated effects on electronic transitions related to fluorescence [2],

[0063] Enhanced Fluorescence Spectral Fingerprinting (FSF)

[0064] The rapid detection of SCRAs can be enhanced by augmenting a FSF detection methodology through photochemical reactivity tracking [1],

[0065] Such an approach recognises that SCRAs are typically built on a scaffold that includes a central ‘core’ group. There are over 10 different moieties that have been identified as core groups in SCRA compounds including: pyrrole, carbazole and more recently, oxoindole found in the emerging “OXIZID” SCRA group. However, indole and indazole are by far the most commonly identified core in SCRA compounds, found in over 75 % of SCRAs notified by the EMCDDA. Both indole and indazole are photochemically active and are sensitive to substituents on the ring system.

[0066] SCRA FSFs are highly sensitive to chemical substitution, attributed to changes in electronic structure and the degree of cross-conjugation.

[0067] The data set out in [1] show that FSFs are extraordinarily sensitive to subtle changes in chemical structure and point to the rationale for sensitivity towards different SCRAs observed previously [2], More specifically, it envisages shifts in the distribution of conformational states and consequently electronic structures. Therefore, shifts in cross-conjugation may be the drivers of the observed differences in the FSFs. This is considered in detail below. In particular, the data of [1] relates to SCRA compounds containing a range of structural groups including indole, indazole and oxoindole cores, and amino acid-derived linked groups. All five compounds studied were affected by UV irradiation, with the evolution of new products evident in all five FSF difference (post vs pre photochemical change) maps. Although the majority of pre-degradation FSFs for the SCRAs under study appeared remarkably similar (with exceptions such as BZO- HEXOXIZID), the post-degradation FSFs are highly distinct, indicating potential for discrimination of SCRA following photochemical degradation.

[0068] Applicability of Enhanced Fluorescence Spectral Fingerprinting (FSF) to non-SCRA substance detection

[0069] Aspects described recognise that the hybrid FSF and photochemical fingerprinting approach described in relation to SCRA detection in [1] may have applicability to test substances other than those in solution and / or to substances other than SCRA compounds.

[0070] Many aromatic molecules are photochemically active, meaning either they rapidly (relatively) degrade in the presence of specific wavelengths of irradiation and / or that they undergo photochemical reactions with, for example, a solvent in which they are placed, themselves, or other molecules of the same species. Those photochemical reactions may give new photoproducts that have altered absorption / emission fluorescence spectra. As a result, a hybrid fluorescence fingerprinting and photochemical transition approach may offer a route to detection of some aromatic molecules. In particular, aspects described recognise that monitoring changes in an excitationemission matrix (spectral fingerprint; FSF) of a molecule, in combination with photochemical degradation, allows discrimination of certain molecules. In other words, an aromatic molecule may have an associated “hybrid photochemical fingerprint”. The fingerprint according to described aspects comprises a signal attributable to fluorescence emission from a test substance.

[0071] It is not a priori possible, at least to a reasonable level of tractability, to predict the photochemical products of specific molecules and how this will affect their emission / absorption spectra in a given solvent or solid environment. For clarity, such in silico calculations are possible, but do not yield full excitation emission maps, or in a manner that is timely and therefore is not routinely tractable.

[0072] It is therefore difficult to predict which aromatic molecules are candidates for detection via the methodology described in detail in [1],

[0073] The inventors have recognised that the hybrid fluorescence photochemical fingerprinting methodology supports the discrimination of a range of illicit drugs from the following classes: cannabinoid (including, of course, the synthetic cannabinoid compounds described in [1]); opioid (including synthetic opioids); benzodiazepine; cathinone (mephedrone); steroid (CDMT) and sedative (xylazine).

[0074] Methodology

[0075] Intrinsic fluorescence spectroscopy (IFS) does not require artificial probes since it detects fluorophores which exist as natural components of an analyte material. Approaches described recognise that individual aromatic compounds may have a naturally occurring characteristic excitation and emission fluorescence spectra. A two- dimensional excitation / emission matrix (EEM; FSF as above) therefore could contain a detailed report on the chemical composition of a compound under test. The discriminatory ability of fluorescence, for those compounds which have a fluorescence response, is therefore potentially extremely high. Coupled with this, many aromatic molecules exhibit a photochemical response, as described above. That photochemical response may result in a detectable change in a fluorescence response of a compound and therefore the combination of a fluorescence and photochemical fingerprinting methodology may have significant benefits. A general methodology for performing a hybrid fluorescence photochemical fingerprinting method according to aspects may comprise the following steps:

[0076] Step 1: Irradiation of a sample under test, sequentially across a plurality of excitation wavelengths. In one example methodology, the plurality of excitation wavelengths comprise: 255nm, 265nm, 275nm, 285nm, 295nm, 305nm, 320nm, 340nm, 365nm, 375nm, 385nm, 395nm and 405 nm. It will be appreciated that a difference plurality of excitation wavelengths may be selected. Such excitation wavelengths may be selected such that they are spaced at similar reasonable intervals to achieve coverage of a desired excitation spectral range.

[0077] Step 2: Collection of emission from the sample under test at each of the excitation wavelengths. That collection may comprise a full spectral acquisition, for example, using a monochromated spectrometer.

[0078] Step 3: Irradiation of the sample under test at a wavelength or wavelengths determined to be likely to induce a photochemical change in the sample under test. That wavelength, or wavelengths may, for example, be selected to be at, or near to, an absorption maximum of the sample under test (or maxima, or as a combination of wavelengths that produce a change in the spectral fingerprint). The irradiation intended to induce a photochemical change may occur for a period of time and / or an intensity selected to induce a measurable change in a spectral fingerprint obtained via step 2. It will be appreciated that various methods to determine appropriate irradiation likely to induce photochemical change, for those substances in a sample likely to be subject to such a change, can be implemented. By way of general example:

[0079] Determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample may comprise determining a wavelength of an absorption maxima of the provided sample and irradiating the provided sample with irradiation having a wavelength close to the determined absorption maxima to induce a photochemical change in the provided sample.

[0080] Determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample may comprise: measuring an absorption spectrum of a plurality of drugs and evaluating the measured absorption spectra to select one or more wavelength for irradiation of the provided sample. The evaluation may, for example, comprise selecting a range of wavelengths for irradiation, that range being selected to encompass the wavelengths determined to induce a change in the drugs in the library.

[0081] The wavelength for irradiation may comprise a wavelength, a plurality of wavelengths, or range of wavelengths in the ultraviolet region of the spectrum. The wavelength for irradiation of the provided sample may comprise a wavelength, or plurality of wavelengths, in the range from around 230nm to around 400nm.

[0082] In some implementations, for example, a provided sample may be irradiated with broadband UV, or cycle different UV wavelengths. Such an approach may induce a photochemical change across a large range of drugs in a library and therefore result in a reasonable change that a photochemical change will be induced if a drug of interest is present in a provided sample.

[0083] Step 4: Repetition of steps 1 and 2 to enable collection of emission from the photochemically changed sample under test as full spectral acquisition, for example using a monochromated spectrometer.

[0084] Step 5: Comparison of the fingerprints obtained in Step 2 and Step 4. In some implementations, the comparison may comprise creation of a difference map between the fingerprints obtained in steps 2 and 4 to give the hybrid photochemical fingerprint of the sample under test.

[0085] Step 6: Evaluation of one or more of the fingerprints or comparison of fingerprints obtained in steps 2, 4, or 5 to identify the sample under test. In some implementations, the evaluation may comprise comparison to a library of hybrid photochemical fingerprints of known substances. The comparison may comprise looking for identity or matching, a match within a threshold or similar and may occur by means of statistical analysis, including machine learning approaches.

[0086] It will be appreciated that changes in fingerprint may occur in both the ultra-violet and visible spectral regions. Furthermore, assessment of photochemical fingerprints might be conducted visually, where there is, for example, an obvious (visible to the human eye, for example) colour change in or on the provided sample.

[0087] The hybrid photochemical fingerprinting methodology described captures and includes information on both new fluorescent species that emerge as a result of photochemical reactions but also the loss of fluorescent / absorptive species as they are photochemically degraded. Both of these physical changes are reflective of the specific chemistry of the analyte.

[0088] Apparatus

[0089] FIG. N1A to N1E illustrate various aspects of an apparatus configured to perform the hybrid photochemical fingerprinting method described generally above.

[0090] FIG. N1A illustrates schematically some main components of an apparatus configured to perform the hybrid photochemical fingerprinting method described generally above. The apparatus 1 comprises: an LED ring 10 configurable to irradiate a sample (not shown in FIG. N1A) and a spectrometer 20 configurable to collect emission from the sample. The apparatus 1 further comprises a microcomputer 30, configured to control operation of the LED ring 10 via LED drivers 40, and to control operation of the spectrometer 20. The microcomputer 30 may comprise reconfigurable storage. That storage may be configured to store, temporarily or otherwise, data generated by the spectrometer and / or the LED drivers. The storage may be coupled with a processor, configured to process and evaluate the data generated by the spectrometer and / or the LED drivers. The storage may comprise a locally held library of hybrid photochemical fingerprints associated with a range of substances. In an alternative implementation, the apparatus may comprise communication circuitry, configured to communicate with a remote library of hybrid photochemical fingerprints associated with a range of substances.

[0091] The apparatus of FIG. N1A further comprises an operation button 50 in communication with the microcomputer to initiate various phases of the photochemical fingerprinting method, a display 60 to allow a user to interface with the apparatus 1 and receive information about the photochemical fingerprinting method and the result of that method in relation to a sample under test.

[0092] The apparatus of FIG. N1A also comprises a temperature sensor 70, in communication with the microcomputer 30. Knowing the ambient temperature, or the temperature of a sample under test may allow an assessment to be made regarding, for example, irradiation duration for the purposes of induction of a photochemical change in a sample under test. The apparatus of FIG. N1A also comprises an accelerometer 80, in communication with the microcomputer 30. The signal from the accelerometer may be used to determine whether the apparatus and / or sample are moving and therefore potentially whether an obtained set of results are likely to be valid.

[0093] FIG. N1 B is a photograph of an LED ring 10 for use in an apparatus according to an aspect. The LED ring of FIG. N1A shows 12 equally spaced LEDs 12 mounted on a concave annular base 14 such that each LED is positioned to irradiate a sample placed towards the central portion of the annulus. In the LED ring of FIG. N1 B, the LEDs are in a 1-inch diameter ring arrangement, equally circumferentially spaced. An aperture 16 is provided in the centre of the annular base 14.

[0094] FIG. N1C and FIG. N1 D are photographs of a spectrometer 20 and LED ring 10 for use in an apparatus according to an aspect. FIG. N1C shows the spectrometer 20 in a custom housing mountable on, and connectable to, the LED ring 10. A collimating lens 25 is provided in the front of the spectrometer in the region of the aperture 16 of the LED ring 10. The entrance of the collimating lens 25 in the apparatus shown is arranged such that it is Iocatable15 mm from the sample surface. FIG. N1 D is a side view showing that the entrance to the spectrometer 20, via which emission from a sample is collected, is aligned centrally with the aperture 16 provided in the LED ring 10.

[0095] FIG. N1 E is a photograph of a complete device 1 showing an outer housing 100 in which the LED ring 10, spectrometer 20, microprocessor 30 and other components are located. On the outside of the housing 100 the multifunctional buttons 50 and the display 60 can be seen. FIG. N1 E also shows a sample holder 200 for liquid samples. The sample holder 200 comprises a central sample well 210. In the implementation shown, the central sample well 210 comprises black HDPE, with a custom machined well which is 1 inch wide, 10 mm deep and of a true hemispherical construction. The sample holder 200 further comprises an alignment guide 220, in this case, in the form of a shaped protrusion configured to abut a side of housing 100 when the apparatus 1 is aligned and in a position to test a sample located in the sample well 210. The geometry and arrangement of the LEDs of the LED ring relative to the entrance slit of the spectrometer 20 can significantly impact the resultant spectral fingerprints and the photochemical changes / degradation of the samples. Shown here is one possible implementation. The sample holder 200 is similarly important for the resultant spectral fingerprints. That is to say, the material and shape of the sample holder may affect the resultant spectral fingerprints. The implementation shown and described is one possible implementation having geometry optimised as described above. The shaping, configuration and design, together with material selection mitigates possible photochemical damage to the sample holder that would otherwise affect the resultant spectral fingerprints, as well as balancing the signal intensity and tractability of use in a practical setting (including, for example, cleaning between samples).

[0096] Photochemical Fingerprinting for Substances other than Synthetic Cannabinoids

[0097] Tetrahydrocannabinol (THC)

[0098] Cannabidiol (CBD) is a generally legal substance; tetrahydrocannabinol (THC) is a psychoactive substance which is generally not legal. CBD products should not contain THC. The disclosure of [1] is confined to the study of SCRAs. In fact, [1] details a study of a series of SCRA model systems (which mimic a specific SCRA known as AM- 694). The spectrochemical properties of molecular systems are highly dependent on their structure. The SCRA model systems in [1] feature electronegative halogen substituents. The SCRA model systems in [1] also feature an electronegative indole N- atom. Both of these structural features contribute significantly to the observed fluorescence properties and degradation of these model systems, but are crucially absent in the THC molecule. There is no disclosure or teaching in [1] that the THC molecule would be expected to exhibit a similar fluorescence sensitivity and would exhibit characteristic degradation of the type that would enable it to be fingerprinted in the way described in [1], Nonetheless, it has been determined that a photochemical fingerprinting methodology according to [1] can be used to detect and identify the presence of THC in a solution.

[0099] FIG. N2A-C show graphically the emission spectra of CBD, THC and a combination irradiated over time with a 265nm irradiation source to induce a photochemical change. Figure N2 shows the emission spectra of CBD, THC and the combination irradiated over time with a 265 nm source. Each subsequent spectrum represents a new time point of data collection (every 5 minutes for 30 minutes).

[0100] FIG. N2A shows how a solution of CBD irradiated at 265nm, will show some simple photodegradation in the form of a decrease in fluorescence emission without changes in the structure of the emission band. FIG. N2B shows how a solution of THC shows both photodegradation and new fluorescent species attributable to novel electronic structures (photoproducts), with new peaks at -360 and 380 nm, amongst others when exposed to similar irradiation.

[0101] FIG. N2C shows how, at a 10:1 ratio of CBD:THC, the new peaks from the photoproducts of THC are evident and allows discrimination of presence of THC in the presence of a high molar ratio of CBD.

[0102] It can therefore be understood that, if induction of a photochemical change is implemented, the photochemical fingerprinting methodology described above can be used to identify THC, but also THC in the presence of CBD. This results from the THC having a different photochemical activity compared to CBD, despite the structures being very similar.

[0103] Other molecules

[0104] It is not a simple task to predict whether a molecule is a candidate for detection via the fluorescence photochemical fingerprinting technique described in [1], It has, via experiment, been determined that the hybrid fluorescence photochemical fingerprinting approach of [1] is valuable and important in detection of various substances of abuse, including, for example, opioid (including synthetic opioids); benzodiazepine; cathinone (mephedrone); steroid (CDMT) and sedative (xylazine).

[0105] FIG. N3 shows fluorescence spectral fingerprints (FSFs) obtained pre- and postirradiation to induce a photochemical change, together with a difference map comparison between the FSFs for 6 different molecules (Flunitrazepam, Fentanyl, Mephedrone, Etonitizene, Dihydrocodiene and CDMT in each column left to right) tested in an ethanol solution.

[0106] FIG. N3 shows the spectral fingerprints for a range of molecules and showing their pre / post irradiation fingerprints and the difference map (hybrid photochemical fingerprint) according to various aspects. The examples given are in Ethanol and at a range of concentrations from 100 pg to 2 mg mL-1. The samples were irradiated with broad band UV for - 5 minutes. The background colouration of each figure represents zero as the colour key at right. Note that the difference map data uses a + / - scale. Some implementations recognise that approaches in accordance with aspects may be deployed in relation to molecules which do not have a significant photochemical response. In particular, approaches may be deployed in relation to compounds which have a minimal, but non-zero, photochemical response. A lack of photochemical degradation can itself be indicative of the chemical structure when, for example, combined with a knowledge of an initial spectral fingerprint.

[0107] FIG. N4 shows fluorescence spectral fingerprints (FSFs) obtained pre- and postirradiation to induce a photochemical change, together with a difference map comparison between the FSFs for 5 different molecules (Clonazepam, Diazepam, Alprazolam, Etizolam, and Xylazine in each column left to right) tested in an ethanol solution. The examples given are in ethanol and at a range of concentrations from 100 pg to 2 mg mL-1. Irradiation with broad band UV for ~ 5 minutes. The background colouration of each figure represents zero as the colour key at right. Note that the difference map data uses a + / - scale.

[0108] Accordingly, it is demonstrated that the hybrid photochemical fluorescence fingerprinting methodology can be used to detect a range of substances tested in solution.

[0109] Extension of hybrid photochemical fluorescence fingerprinting to solid substances and substances adsorbed on a physical matrix

[0110] Aspects recognise that the approach described in [1] and above in relation to samples tested in solution can be extended to situations where drugs are are available in a solid, for example, powdered, or tablet form, or adsorbed onto a physical matrix (for example, paper).

[0111] FIG. N5A shows fluorescence spectral fingerprints (FSFs) obtained pre- and postirradiation to induce a photochemical change, together with a difference map comparison between the FSFs for 4 different cases: no drug adsorbed onto a paper matrix; a synthetic cannabinoid adsorbed onto a paper matrix; a Benzodiazepine adsorbed onto a paper matrix; and a Nitazene adsorbed onto a paper matrix. Each row relates to one case. The spectral fingerprints of FIG. N5A for three different drugs on white paper are shown: pre (column at left) and post (middle column) irradiation with broad band ultraviolet light. The column at right shows the corresponding difference maps for each condition. Similar results are achieved if a drug is adsorbed onto yellow or black paper or card.

[0112] FIG. N5B shows a photograph of samples on paper after irradiation to induce a photochemical change. The FIG. gives a visual image of clobazam and etonitazene samples on white paper after irradiation / after being subject to testing using apparatus such as that shown in FIG. N1E, adapted so that the sample holder receives a paper sample, or adapted so that the apparatus 1 in housing 100 is abutted against a sample paper under test. The paper shown on the left of FIG. N5B shows a control where only solvent is added to paper, the middle paper shows paper on which clobazam was added and the right paper shows paper on which etonitazene added. In each case the drug samples are at 100 pg / cm2.

[0113] It can be seen that the photochemical fingerprints (difference maps) vary in a drugspecific manner when the drug is adsorbed onto paper. The change in the fingerprints is reflected both in the change in the signature of the optical brightening agents of the paper itself (centered at -420 nm in Figure N5) but also the loss / gain of new spectral features which are attributable to photochemical degradation / reaction of the adsorbed drugs.

[0114] The changes in the optical brightening agents of the paper is assumed to be due to changes in resonance energy transfer / absorption of the emitted light from the optical brightening agents by the drugs and therefore varying as the drugs are photochemically degraded / reacting to give new products.

[0115] Visual changes are also clear in some cases (as shown in FIG. N5B), where irradiation of the samples gives rise to a visual colour change in addition to the spectral fingerprint shown in FIG. N5A, which is rather more focussed on the ultraviolet region.

[0116] In other words, although the optical brightening agents of paper change their fluorescence in the presence of drugs (see top row of FIG. N5A), they also change characteristically as the photochemical fingerprint in the presence of drugs, thereby supporting use of the hybrid photochemical fingerprinting method directly in relation to drugs adsorbed onto a physical matrix, in this case, white paper.

[0117] Some aspects recognise that the sample under test may be a physical matrix onto which a substance of interest may be adsorbed. An appropriate library of reference photochemical fingerprints may be available to the apparatus and it may be possible for a user to select whether the fingerprinting methodology is being applied to a sample in solution or a sample on a physical matrix.

[0118] In relation to a solid drug form, for example, in the case that a provided sample is a powder or tablet, it is possible adapt the methodologies described herein. In particular, a provided powder may be placed in sample holder 200 and appropriate FSFs acquired pre- and post- photochemical change. An appropriate library of reference photochemical fingerprints may be available to the apparatus and it may be possible for a user to select whether the fingerprinting methodology is being applied to a sample in solution, a sample on a physical matrix or a solid sample.

[0119] FIG. N6 illustrates schematically some components of an apparatus according to some arrangements; and FIG. N7 illustrates schematically steps of methods performed in accordance with some arrangements.

[0120] FIG. N6 shows an apparatus 9000 for drug detection. The apparatus 9000 is configured to identify whether a drug is present in a provided sample. The apparatus comprises generally:

[0121] 9010: circuitry configured to perform determining a first fluorescence spectral matrix associated with the provided sample by communicating with an excitation source and emission detector to effect :excitation of the provided sample at a first excitation wavelength; and reception of a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength.

[0122] The circuitry 9010 being configured to effect repetition of the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength.

[0123] 9020: circuitry configured to perform determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength. The irradiation may be performed by the excitation source or an alternative irradiation source. The excitation and irradiation sources may be substantially co-located within the apparatus 9000.

[0124] 9030: circuitry configured to perform determining a second fluorescence spectral matrix associated with the provided sample by: by communicating with an excitation source and emission detector to effect :excitation of the provided sample at a first excitation wavelength; and reception of a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength. The circuitry 9030 being configured to effect repetition of the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength.

[0125] 9040: circuitry configured to perform comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples. 9050: circuitry configured to perform triggering a positive identification of a drug in the provided sample if a match within a predetermined threshold is revealed by the comparison.

[0126] FIG. N7 illustrates schematically steps of methods performed in accordance with some arrangements. FIG. N7 shows a drug detection method 9100 to identify whether a drug is present in a provided sample, the method comprising:

[0127] 9110: determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength;

[0128] 9120: determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength;

[0129] 9130: determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength;

[0130] 9140: comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and

[0131] 9150: if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample. A person of skill in the art would readily recognize that steps of various abovedescribed methods can be performed by programmed computers. Herein, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer readable and encode machineexecutable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of said above-described methods. The program storage devices may be, e.g., digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods. The term non-transitory as used herein, is a limitation of the medium itself (i.e. , tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM).

[0132] As used in this application, the term “circuitry” may refer to one or more or all of the following:

[0133] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[0134] (b) combinations of hardware circuits and software, such as (as applicable):

[0135] (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and

[0136] (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[0137] (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0138] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device. Although example embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

[0139] Features described in the preceding description may be used in combinations other than the combinations explicitly described.

[0140] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0141] Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

[0142] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not particular emphasis has been placed thereon.

[0143] REFERENCES

[0144] [1] “Photochemical Fingerprinting is a Sensitive Probe for the Detection of Synthetic Cannabinoid Receptor Agonists; toward Robust Point-of-Care Detection” Andrews et al, Anal Chem, 2023, 95, 703-713, https: / / doi.o g / 10.1021 / acs.analchem.2c02529.

[0145] [2] B. May, H. A. Naqi, J. A. Scott, I. S. Blagbrough, S. M. Husbands and C. R. Pudney, Anal. Chem., 2019, 91, 12971-12979.

Claims

CLAIMS1. A drug detection method to identify whether a drug is present in a provided sample, the method comprising: determining a first fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; determining a wavelength for irradiation of the provided sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; determining a second fluorescence spectral matrix associated with the provided sample by: excitation of the provided sample at a first excitation wavelength; and receiving a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample.

2. A drug detection method according to claim 1 , wherein determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: determining a wavelength of an absorption maxima of the provided sample and irradiating the provided sample with irradiation having a wavelength close to the determined absorption maxima to induce a photochemical change in the provided sample.

3. A drug detection method according to claim 1 , wherein determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: measuring an absorption spectrum of a plurality of drugsand evaluating the measured absorption spectra to select one or more wavelength for irradiation of the provided sample.

4. A drug detection method according to any one of claims 1 to 3, wherein the wavelength for irradiation comprises a wavelength in the ultraviolet region of the spectrum.

5. A drug detection method according to claim 1, wherein the drug comprises least one of the following: a photochemically active aromatic molecule; or a molecule which photochemically changes to form an aromatic molecule; or a synthetic cannabinoid receptor agonist; or a cannabinoid; or tetrahydrocannabinol (THC); or an opioid; or a benzodiazepine; or a cathinone; or a steroid or a sedative.

6. A drug detection method according to any preceding claim, wherein the provided sample comprises: a drug in solution.

7. A drug detection method according to claim 6, wherein said provided sample comprises at least one of the following: a drug in ethanol solution; or a drug in saliva; or a combusted drug in saliva.

8. A drug detection method according to any one of claims 1 to 5, wherein the provided sample comprises: a drug adsorbed onto a physical matrix.

9. A drug detection method according to claim 8, wherein the physical matrix comprises paper.

10. A drug detection method according to any one of claims 1 to 5, wherein the provided sample comprises a drug in solid form.

11. A drug detection method according to any preceding claim, wherein triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a first and second fluorescence spectral matrix which both match said determined first and second fluorescence spectral matrix associated with the provided sample within the threshold.

12. A drug detection method according to any preceding claim, wherein triggering a positive identification of a drug comprises identifying which of the plurality of drugsamples in the library is a source of a difference map between a first and second fluorescence spectral matrix which matches a difference map created by comparison of the determined first and second fluorescence spectral matrix associated with the provided sample within the threshold.

13. A drug detection method according to any preceding claim, wherein triggering a positive identification of a drug comprises identifying which of the plurality of drug samples in the library is a source of a difference map between a first and second fluorescence spectral matrix which matches a difference map created by comparison of the determined first and second fluorescence spectral matrix associated with the provided sample, and a first fluorescence spectral matrix which matches a determined first fluorescence spectral matrix associated with the provided sample within the threshold.

14. A drug detection method according to any preceding claim, wherein irradiating the provided sample comprises irradiating the provided sample for a predetermined time period at a selected intensity and optionally , wherein the predetermined time period and intensity are selected to be likely to induce a photochemical change in a drug in the provided sample.

15. Apparatus configured to identify whether a drug is present in a provided sample, the apparatus comprising: a controller, an excitation source and an emission detector; the controller comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the controller at least to perform: determining a first fluorescence spectral matrix associated with the provided sample by: causing excitation of the provided sample by the excitation source at a first excitation wavelength; and receiving, from the emission detector, a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; storing excitation and emission data obtained in each excitation and receiving step; andcommunicating with the stored data to create the first fluorescence spectral matrix associated with the provided sample; determining a wavelength for irradiation of the provided sample to induce a photochemical change in the provided sample and irradiating the provided sample with radiation having the determined wavelength; determining a second fluorescence spectral matrix associated with the provided sample by: causing excitation of the provided sample by the excitation source at a first excitation wavelength; and receiving, from the emission detector, a fluorescence emission spectrum generated by the provided sample at the first excitation wavelength; repeating the excitation and receiving steps across a range of excitation wavelengths which differ from the first excitation wavelength; storing excitation and emission data obtained in each excitation and receiving step; and communicating with the stored data to create the second fluorescence spectral matrix associated with the provided sample; comparing the determined first and second fluorescence spectral matrix associated with the provided sample with a library of first and second fluorescence spectral matrices obtained from a plurality of drug samples; and if a match within a predetermined threshold is revealed by said comparison, triggering a positive identification of a drug in the provided sample.

16. An apparatus according to claim 15, wherein the drug comprises least one of the following: a photochemically active aromatic molecule; or a molecule which photochemically changes to form an aromatic molecule; or a synthetic cannabinoid receptor agonist; or a cannabinoid; or tetrahydrocannabinol (THC); or an opioid; or a benzodiazepine; or a cathinone; or a steroid or a sedative.

17. An apparatus according to any one of claims 15 or 16, wherein the provided sample comprises: a drug in solution, and optionallywherein said provided sample comprises at least one of the following: a drug in ethanol solution; a drug in saliva; a combusted drug in saliva.

18. An apparatus according to any one of claims 15 to 17, wherein the provided sample comprises: a drug adsorbed onto a physical matrix; or a drug in solid form.

19. An apparatus according to claim 18, wherein the physical matrix comprises paper.

20. A drug detection apparatus according to claim 15, wherein determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: determining a wavelength of an absorption maxima of the provided sample and irradiating the provided sample with irradiation having a wavelength close to the determined absorption maxima to induce a photochemical change in the provided sample.

21. A drug detection method according to claim 15, wherein determining a wavelength for irradiation of the sample to induce a photochemical change in the provided sample comprises: measuring an absorption spectrum of a plurality of drugs and evaluating the measured absorption spectra to select one or more wavelength for irradiation of the provided sample.

22. An apparatus according to any one of claims 15 to 21 , wherein said excitation source comprises: an array of different LEDs selected to have an emission spectrum which, when taken together, spans a wavelength range from 250nm to 400nm and optionally wherein said controller is configured to control said array of different LEDs to selectively switch one or more LEDs in said array on or off and thereby control said first wavelength.

23. An apparatus according to any one of claims 15 to 22, wherein the emission detector comprises a monochromated spectrometer.

24. An apparatus according to any one of claims 15 to 23, wherein the library is stored on locally provided memory; and optionally wherein the apparatus comprises communication circuitry configured to communicate with a remotely stored library.

25. A computer program product operable, when executed on a computer, to perform the method of any one of claims 1 to 14.

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