Sample collection apparatus

Abstract

A fluid sample collection apparatus comprising an end cap 100 comprises a composition comprising a substance for us as an Internal Standard 104 sealed within the end cap in an atmosphere that protects

Description

Device The present invention is directed towards a fluid sample collection apparatus comprising an end cap comprising a substance suitable for use as an Internal Standard, which composition is sealed within the end cap in an atmosphere that protects the substance for use as an Internal Standard against degradation and wherein the end cap is configured to be couplable to a sample vessel and to controllably release the composition to the interior of the sample vessel. The present invention also relates to a sample vessel for fluid sample collection, which comprises a substance suitable for use as an Internal Standard that is sealed in an atmosphere that protects the substance for use as an Internal Standard against degradation and wherein the sample vessel comprises means for removing the composition from the protective atmosphere and introducing it into the sample vessel concurrently with a provision of a sample. The present invention also relates to a kit-of-parts comprising the fluid sample collection apparatus and / or the sample vessel, along with methods and uses of the same. Background of the Invention Many clinical treatments require the analysis of compounds within bodily fluid samples, such as blood serum levels of drugs. For example, dose-ranging is an integral part of phase I and / or phase II clinical trials. The main aim of dose-ranging studies is to analyse the half-lives of drugs in healthy volunteers in both plasma and urine, and this requires multiple bodily fluid samples being taken over wide spanning time ranges and the concentrations of the drugs in these samples being measured. In the advent of personalised medicine, by analysing an individual's response to certain drugs in terms of blood plasma levels, drug dosing can be tailored to that person's response arriving at a dose which is both more effective and results in fewer side effects. Also, in some settings some patients require ongoing bodily fluid sampling to analyse target compound concentrations, for example recovering drug addicts. Typically, to analyse bodily fluids subjects need to go to a clinical setting where a medical professional obtains a sample and sends this to a laboratory for analysis. For blood samples these are often obtained by venous puncture and drawing large volumes of blood which are then sent for analysis. The half-life of drugs in blood varies and even on being drawn out of the body drugs often continue to degrade. Therefore, during the time between the sample being taken and analysis in the laboratory, the drug degrades often at unknown rates meaning that any reliable quantification of drug levels at the time of sampling cannot be achieved. Therefore, there is a need for apparatuses and methods which allow for the quantification of drug levels in fluid samples at the time of the samples being taken. WO 2020 / 156849 describes methods for analysing concentrations of biomarkers in blood samples which method comprises providing a kit of parts for sampling blood comprising a lancet and a capillary, a vial comprising an extraction fluid and one or more Internal Standards, distributing the kit of parts to the mammal, receiving the vial comprising a blood sample inserted into the vial, analysing the sample to determine the quality of the sample and the concentration of the one or more biomarker in the blood of the mammal by centrifuging the vial and performing a direct analysis of the supernatant. Such kits have utility in that only a small amount of blood sample is required. However, to provide accurate data on drug concentrations in blood at the time of sampling the sample must be processed as quickly as possible after being taken, meaning that for accurate analysis the sample must be taken in a clinical setting with quick access to analysis instruments. Any delay in analysis will ultimately result in the analysis losing accuracy. Therefore, there is a need for improved apparatuses and methods that achieve high levels of accurate analysis of drug concentrations in samples which are not affected by delays in onward sample analysis and allow for subjects to self-sample outside of a clinical setting. Description of the Invention According to the present invention there is provided a fluid sample collection apparatus comprising an end cap, wherein the end cap comprises a composition comprising a substance suitable for use as an Internal Standard, wherein the composition is sealed within the end cap in an atmosphere that protects the substance suitable for use as an Internal Standard from degradation and wherein the end cap is configured to be couplable to a sample vessel and to controllably release the composition to the interior of the sample vessel, which apparatus is referred to hereinafter as "the apparatus of the invention". For the avoidance of doubt, the substance suitable for use as an Internal Standard may, interchangeably, be referred to herein as "the Internal Standard" or "IS". By the term Internal Standard in the context of chemical analyses, we refer to compounds that are used for the detection of sample losses of the analyte to be determined. Internal Standards are known substances with similar analytical behaviour to the substance to be evaluated, e.g. a stable or analogue isotope of the analyte. In contrast to external standards, these substances are located in the sample and are "also treated" - thus internal. In chromatographic bioanalysis for example, an Internal Standard is added to all samples, including calibration standards, as well as quality controls and samples before extraction. Therefore, Internal Standards serve as a reference for analysing and quantifying the presence of target compounds / moieties present in a sample. The end cap may be couplable to the sample vessel in any way to achieve a seal, such as being couplable to the top or the bottom of the sample vessel. Preferably the end cap is couplable to the top of the sample vessel. By the term "sample vessel" we refer to a container having a reservoir that is suitable for holding and retaining a fluid sample. Such a vessel may have an opening to which the end cap as defined herein may be coupled. The end cap may be reversibly couplable or permanently couplable to the sample vessel. For example, when reversibly couplable when in use the user may be able to couple the end cap to the sample vessel and, once the composition has been released into the interior of the sample vessel, the end cap may be removed. The end cap may be reversibly couplable to the sample vessel by any means known in the art. For example, the end cap may be a screw cap comprising a threaded portion and the sample vessel may comprise an opposing threaded portion such that the end cap can be screwed onto the sample vessel in use and then removed by unscrewing. Alternatively, the end cap may be configured such that it is push-fit onto the sample vessel and can be removed. When the end cap is permanently couplable to the sample vessel, the end cap and / or the sample vessel may comprise locking means (e.g., a locking mechanism) such that when the end cap is coupled to the sample vessel it locks into place and the user is not able to remove the end cap without, for example, specialist equipment or breaking apart the apparatus. That is to say, when stating that the end cap is permanently couplable to the sample vessel, the end cap may still be removed, or the interior of the sample vessel may still be accessed so that the sample can be analysed, but in doing so the apparatus will be required to be damaged such that it is not reusable. The apparatus may, therefore, be for single use. Furthermore, the apparatus may be sterilized and be provided in a sealed package for single use. By the composition being sealed within the end cap in an atmosphere that protects the Internal Standard from degradation, this means that the composition comprising the Internal Standard is stored within the end-cap that is protected both from the atmosphere external to the end cap and from sunlight. For example, the composition may be stored in an area within the end cap which is surrounded by materials which light is not able to penetrate. Furthermore, the atmosphere in which the Internal Standard is stored may be an inert atmosphere that prevents degradation of the Internal Standard. For example, the atmosphere may be an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere). The end cap may comprise an aperture for receiving a sampler with the composition comprising the Internal Standard being positioned within the aperture and wherein the end cap is configured to release the composition into the interior of the sample vessel by introducing a sampler through the aperture. The sampler may be configured to sample a defined volume of sample fluid. For example, the sampler may be a capillary tube which is configured to sample a defined volume of sample fluid. The sampler may comprise a handle portion and the sampler may be removable from the handle portion such that once the sampler has been used to introduce the sample into the sample vessel it can be removed from the handle. The handle portion may also function as a lid for attaching / coupling to the top of the end cap once the sampler has been introduced through the aperture. For example, the handle portion may comprise a threaded portion with the end cap comprising an opposing threaded portion such that once the sampler has been introduced through the aperture the handle portion can be screwed onto the end cap to function as a lid. Other means of coupling the handle portion to the end cap are envisaged, such as using push-fit means. As an alternative to using a capillary tube, the sampler may be a pipette or a syringe which is configured to sample a defined volume of fluid and is configured to pass through the aperture thus releasing the composition to the interior of the sample vessel. In use, following entry the fluid sample may be released from the pipette or syringe into the interior of the sample vessel by squeezing the pipette bulb or advancing the plunger through the syringe. After this the sampler may be removed from the sample vessel and the end cap closed with a lid, such as a lid as defined above with respect to the capillary handle. Therefore, the apparatus may also comprise a lid that is couplable, either reversibly or permanently, to the end-cap. Such samplers may be configured to sample a defined volume of fluid that the user cannot adjust, or, alternatively, the samplers may comprise volume markings such that the user can sample a certain volume of fluid and judge this by eye, meaning that a range of volumes can be sampled if required. The sampler may be configured to sample any predetermined volume of fluid. For example, the sampler may be configured to sample from 10 to 500 pL, such as 10 to 200 pL, for example from 10 to 100 pL, and preferably 20 to 50 pL of fluid. By the sampler being configured to sample a predetermined volume of fluid, this reduces the risk of sampling error and increases the accuracy of the sampling and subsequent analysis. The fluid to be sampled may be, for example, a bodily fluid, such as blood, urine or saliva. The fluid to be sampled may come from any source, such as an animal subject (e.g. a mammal, such as a human or animal). The source may also be, for example, a water sample (e.g. drinking water sample or waste water sample) or any other sample that may comprise, or be suspected of comprising, target compounds. The composition may be sealed on both sides of the aperture by an upper and a lower penetrable film, such that on the sampler being introduced through the aperture the penetrable films are broken resulting in the composition being released into the interior of the sample vessel. Any film that provides a seal, but is able to be penetrated by the sampler may be used. For example, the film may be an aluminium foil film, a plastic film or a plastic coated aluminium film. The composition comprising the substance suitable for use as an Internal Standard may be a matrix composition. The purpose of the matrix is to absorb the Internal Standard and to release the standard to the solution simultaneously with the biological sample by the catch and release principle. The purpose with the matrix is also to protect the analyte from un-desired by reactions such as solvolysis, reaction between solvents in the tube or atmosphere (water, alcohol or other reactive solvents). The matrix composition can comprise, for example, a reverse phase silica stationary phase or a polymeric stationary phase that retains the Internal Standard(s) by hydrophobic interactions delivered from the incorporated aliphatic groups (C1-C18 chains, phenyl, diphenyl or other functional groups used within the art of liquid chromatography). These matrix compositions may also or alternatively comprise a mixed-mode stationary phase, reversed silica or a polymeric phase, modified with polar groups such as aromatic or aliphatic hydroxyl groups, aromatic or aliphatic amines or other groups that retain the Internal Standard by both hydrophobic interactions and polar interactions, with anionic interactions and cationic interactions. The matrix composition may also or alternatively comprise a reversed phase silica gel or a polymer (e.g., polypropylene, polyethylene, polyamide etc.) which absorbs the Internal Standard. The matrix composition may also comprise a cosolvent (e.g., Pure C8 MTC oil, mineral oil, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), natural oils and methyl esters of their constitutive fatty acid such as rapeseed methyl ester and others), preferably added in small amounts to increase the release reaction rate and increase the solubility of a poorly soluble compound. The matrix composition may also or alternatively comprise a solid phase that is soluble in any solution, such as an analysis / extraction solution, used in the tube (e.g., protein precipitation solutions, anticoagulants or other solvent mixtures employed to preserve the analytes in biological fluids and / or facilitate the analysis). For example, the composition may comprise excipients into the matrix of which the substance suitable for use as an Internal Standard may be incorporated. The matrix composition may further comprise a solid (e.g. a solid made of tert-butanol, carboxymethylcellulose, Arabic gum, coconut wax etc.) containing the Internal Standard but being soluble in the solvents used for protein precipitation (i.e. the solvents in the analysis / extraction solution as defined below). To further increase the stability of the Internal Standard absorbed to a matrix, scavengers, such as antioxidants (vitamin-E, beta carotene, 2 6-diisopropylphenol) can be can be comprised in the composition to further protect the Internal Standard. The matrix composition may comprise silica particles onto which the substance suitable for use as an Internal Standard may be adsorbed such that on entry into the sample vessel interior the substance may be released from the surface of the silica particles. The composition may be a dry pellet and may also be shaped so as to enable the dry pellet to penetrate the films on the application of pressure. For example, the end of the dry pellet that is towards the lower penetrable film may be shaped to a tapered point, such that when the sampler is passed through the aperture of the end cap this places pressure on the top of the dry pellet and, with the bottom end of the pellet being tapered, this pierces the lower film causing the pellet to enter the interior of the sample vessel. According to another aspect of the invention there is provided a kit-of-parts comprising a sample vessel, a sampler configured to sample a defined volume of sample fluid and an end cap as defined above, wherein the sample vessel and end cap are configured to be couplable together. The kit-of-parts may comprise a plurality of sample vessels, samplers and end caps. By the term plurality we envisage at least 10, such as at least 20, 30, 40, 50 or 100 of each component of the kit-of parts. In the kit-of-parts the sample vessel may comprise an analysis / extraction solution, which may be an analysis / extraction solution as defined above. The kit-of-parts may further comprise a lancet. For the avoidance of doubt, by the term "lancet" we refer to a skin-puncturing device which comprises needles or narrow, sharp blades that poke a small hole in the skin obtain capillary blood. In the context of the present invention the lancet is used to extract blood of the subject through the skin for the sampler to draw up. The sampler included in the kit-of-parts may be a sampler as defined above. In an alternative aspect of the invention, there is provided a sample vessel for fluid sample collection for future analysis, the sample vessel comprising: a reservoir; a composition comprising a substance suitable for use as an Internal Standard in said analysis; wherein the composition is sealed within an atmosphere that protects the substance suitable for use as an Internal Standard from degradation; and wherein the sample vessel comprises means for removing the composition from the protective atmosphere and introducing it to the reservoir concurrently with a provision of a sample to the reservoir, which sample vessel is referred to hereinafter as "the sample vessel of the invention" The sample vessel of the invention may comprise any of the features as defined above in relation to the apparatus of the invention. In particular, the sample may be provided to the reservoir by using a sampler as defined above. Furthermore, the sample vessel may be a sample vessel as defined above. By the term concurrently, it is meant that the sample and the composition are introduced into the sample vessel at substantially the same time. For example, the composition may be introduced into the reservoir within one minute of the sample, such as within 30, 20 or 10 seconds, for example within 9, 8, 7, 6, 5, 4, 3, 2, or 1 second of the sample. The sample vessel of the invention may be comprised in a kit-of-parts, which may contain any of the further features detailed above in respect of the kit-of-parts containing the end cap. The kit-of-parts may comprise a plurality of sample vessels, such as at least 10, for example at least 20, 30, 40, 50 or 100 sample vessels. The apparatus of the invention and the sample vessel of the invention may both be used for sampling a fluid, e.g. bodily fluid, such as blood, urine, or saliva. Such a use can be to sample a target compound in the fluid for future quantification and qualification. Such a compound may be a biomarker, a pharmaceutically active compound, endogenous or exogenous toxins, illegal drugs, veterinary drugs or other chemicals that are valuable to measure in bodily fluids, preferably in blood. Herein chemicals, compounds and biomarkers that may be present in one or several body fluid sample(s) may be referred to as "target chemicals / compounds" or "analytes". The apparatus / sample vessel is envisaged to be supplied to end users with the compound for analysis having been predetermined and, therefore, the Internal Standard included in the composition may have been preselected as a suitable Internal Standard for future analysis, quantification and / or qualification of the target compound. With the composition comprising the Internal Standard being stored in an atmosphere that protects it from degradation, at the time of supplying the apparatus to the user the amount of non-degraded Internal Standard will be known. On releasing the composition comprising the Internal Standard to the interior of the sample vessel at the same time the Internal Standard and target compound will degrade at the same rate, meaning that on future analysis the concentration of the target compound in the fluid at the time of sampling can be reliably determined based on the relative concentration of the Internal Standard on the basis that the Internal Standard and target compound degrade at the same rate. One particular advantage of the present invention is that samples may be taken by the user (e.g., patient) themselves rather than needing a medical professional. Therefore, the patient may sample the bodily fluid at home rather than in a hospital setting. Another advantage of the present invention is that samples do not need to be analysed immediately on being taken to reliably calculate concentrations of target compounds in the fluid sample, which means that delays in laboratory analysis will not impact the reliability of the analysis. This means that the technology is suitable for regular mail transport to the laboratory without this impacting the reliability of the analysis due to variations in time from sampling, through to delivery and then to analysis. In addition, users can be supplied with kit-of-parts comprising multiple apparatuses allowing for the sampling of bodily fluids over a period of time. Therefore, such apparatuses can be useful in, for example, precision medicine settings by sampling blood serum levels of an active pharmaceutical ingredient over time after taking a drug composition and, following analysis of target compound levels in the sample, the drug dose may be tailored to that particular patient. Following from this, such kits may also find use in clinical trials where rather than keeping trial candidates in hospital settings for analysing blood serum levels they can take samples themselves and send the samples on for further analysis in a laboratory setting. The apparatus may, therefore, be for use in sampling blood serum levels of pharmaceutically active compounds that have been administered to a subject. The subject may be a mammal, such as a human or animal. Suitable target compounds that may been sampled by the present invention may be compounds that have a narrow therapeutic index, such as those selected from the list consisting of Abemaciclib, Acalabrutinib, Acenocoumarol, Alatrofloxacin, Aldesleukin, Alectinib, Alemtuzumab, Alpelisib, Altretamine, Amikacin, Amineptine, Aminoglutethimide, Aminophylline, Amiodarone, Amitriptyline, Amitriptylinoxide, Amoxapine, Amphotericin B, Amsacrine, Anagrelide, Arbekacin, Argatroban, Arsenic trioxide, Asparaginase Erwinia chrysanthemi, Asparaginase Escherichia coli, Astemizole, Atezolizumab, Avelumab, Axitinib, Azacitidine, Baricitinib, Bekanamycin, Belinostat, Bendamustine, Bevacizumab, Bicalutamide, Binimetinib, Bleomycin, Blinatumomab, Bortezomib, Bosutinib, Brentuximab vedotin, Brigatinib, Busulfan, Butriptyline, Cabazitaxel, Cabergoline, Cabozantinib, Capecitabine, Capreomycin, Carbamazepine, Carboplatin, Carfilzomib, Carmustine, Cemiplimab, Ceritinib, Cetuximab, Chlorambucil, Chloramphenicol succinate, Cisplatin, Cladribine, Clofarabine, Clomipramine, Clonidine, Cobimetinib, Colistin, Conivaptan, Copanlisib, Crizotinib, Cyclophosphamide, Cyclosporine, Cytarabine, Dabrafenib, Dacarbazine, Dacomitinib, Dactinomycin, Dalfampridine, Daratumumab, Dasatinib, Daunorubicin, Decitabine, Denileukin diftitox, Desipramine, Dibekacin, Dibenzepin, Dicoumarol, Digitoxin, Digoxin, Dihydroergotamine, Dinutuximab, Docetaxel, Dofetilide, Dosulepin, Doxorubicin, Dronedarone, Durvalumab, Elotuzumab, Enasidenib, Entrectinib, Epirubicin, Erdafitinib, Ergotamine, Eribulin, Erlotinib, Etoposide, Everolimus, Flecainide, Floxridine, Fludarabine, Fluindione, Fluorouracil, Fosphenytoin, Gallium nitrate, Gemcitabine, Gemtuzumab ozogamicin, Gentamicin, Gentamicin Cla, Heparin, Hydroxyurea, Idarubicin, Idelalisib, Ifosfamide, Imipramine, Imipramine oxide, Inotuzumab ozogamicin, Interferon alfa-2b, lobenguane, Ipilimumab, Iprindole, Irinotecan, Isatuximab, Isepamicin, Ivosidenib, Ixabepilone, Ixazomib, Kanamycin, Levacetylmethadol, Levothyroxine, Lithium carbonate, Lithium citrate, Lithium hydroxide, Lomitapide, Lomustine, Mechlorethamine, Melitracen, Melphalan, Melphalan flufenamide, Mercaptopurine, Methotrexate, Micronomicin, Midostaurin, Mitomycin, Mitotane, Mitoxantrone, Mogamulizumab, Moxetumomab pasudotox, Mycophenolic acid, Necitumumab, Nedaplatin, Nelarabine, Neomycin, Neratinib, Netilmicin, Nilotinib, Niraparib, Nortriptyline, Olaparib, Omacetaxine mepesuccinate, Opipramol, Osimertinib, Oxaliplatin, Paclitaxel, Palbociclib, Panobinostat, Pazopanib, Peginterferon alfa-2°, Pemetrexed, Pentostatin, Pexidartinib, Phenindione, Phenobarbital, Phenprocoumon, Phenytoin, Pimozide, Pixantrone, Plazomicin, Pomalidomide, Ponatinib, Pralatrexate, Procainamide, Procarbazine, Protriptyline, Quinidine, Raltitrexed, Ramucirumab, Regorafenib,, Ribociclib, Ribostamycin, Rituximab, Romidepsin, Rucaparib, Ruxolitinib, Siponimod, Sirolimus, Sisomicin, Sodium phosphate P 32, Sonidegib, Sorafenib, Sotalol, Streptomycin, Streptozocin, Sunitinib, Tacrolimus, Tagraxofusp, Talazoparib, Tamoxifen, Tegafur, Teicoplanin, Temoporfin, Temozolomide, Temsirolimus, Teniposide, Theophylline, Thiopental, Thiotepa, Tianeptine, Tioguanine, Tipiracil, Tizanidine, Tobramycin, Tolvaptan, Topotecan, Trabectedin, Trametinib, Trastuzumab, Trastuzumab emtansine, Trilostane, Trimetrexate, Trimipramine, Uracil mustard, Valproic acid, Vancomycin, Vandetanib, Vemurafenib, Venetoclax, Vinblastine, Vincristine, Vindesine, Vinflunine, Vinorelbine, Vorinostat, Warfarin, Zanubrutinib, Ziconotide and mixtures thereof. The substance suitable for use as an Internal Standard may be a derivative of the target compound that has been predetermined for analysis, which Internal Standard is isotopically substituted (e.g., labelled). The substitution (e.g., labelling) may be via nonradioactive isotopes (i.e. stable isotopes) or via radioactive isotopes. Preferably the Internal Standard is substituted (e.g., labelled) with a stable isotope. Alternatively, the substance suitable for use as an Internal Standard may be a compound that is structurally different to the target compound, but is known to degrade at the same rate as the target compound. Such Internal Standards may be isotope substituted compounds as defined above. The isotope with which the compound is isotopically substituted may be selected from the list consisting of deuterium (2H, d), carbon-13 (13C), nitrogen-15 (15N), oxygen-18 (18O) and mixtures thereof. For the avoidance of doubt, the compound suitable for use as an Internal Standard may be substituted either at a single location or multiple locations. Furthermore, the composition may comprise multiple substances suitable for use as Internal Standard, such that the apparatus is able to be used to sample multiple target compounds for onward analysis, quantification and / or qualification. The present invention may also be used to quantify bodily fluid levels (e.g., blood levels) of antifungal drugs. Such antifungal drugs may be selected from the list presented in the table 1. below, with this table showing suitable Internal Standards that may be incorporated into the composition for analysing the drugs. Table 1. Examples of antifungal drugs and used Internal Standards. Drug Internal Standard Voriconazole Ketocoazole Posaconazole SCH56984 Posaconazole 15N213 Cposaconazole Itraconazole and hydroxyitraconazole Fluconazole lodiconazole lodiconazole analogue Voriconazole, fluconazole, itraconzole, hydroxyitraconazole and posaconazole Cyandimipramine Itraconazole, voriconazole and posaconazole Quinoxaline Voriconazole, fluconazole, posaconazole, itraconazole and hydroxyitraconazole Ketoconazole Fluconazole, itraconazole, Posaconazole, voriconazole, caspofungin and anidulafungin Deuterated compounds Anidulofungin, caspofungin, isavuconazole, micafungin, Posaconazole and voriconazole Itraconazole Fluconazole, itraconazole, Posaconazole and voriconazole Dimethylitraconazole The present invention may also be used to quantify bodily fluid levels (e.g., blood levels) of antiviral drugs. Such antiviral drugs may be selected from the list presented in Table 2. below, with this table showing suitable Internal Standards that may be incorporated into the composition for analysing the drugs. Table 2. Examples of viral drugs and used Internal Standards. Drug Internal Standard Nelfinavir, indinavir, ritonavir, saquinavir and amprenavir Methyl indinavir Zalcitabine, 2,3-dideoxythymidine, 3-azido-3-deoxythymidine, indinavir, abacavir, nelfinavir, saquinavir, nevirapine, lamivudine, ritonavir and lopinavir Cimetidine Nelfinavir, indinavir, ritonavir, saquinavir, amprenavir, lopinavir and M8 A86093 Amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir Ro31-9564 Efavirenz, nelfinavir, nevirapine, saquinavir, zalcitabine, amprenavir, zidovudine, atazanavir, delavirdine, indinavir, lopinavir and ritonavir D5-Saquinavir. Cyclospropyl ritonavir and S-CH3-saquainvir Efavirenz, nevirapine, zidovudine, stavudine, abacavir, lamivudine, zalcitabine, didanosine, indinavir, nelfinavir, ritonavir, atazanavir, saquinavir, lopinavir and amprenavir Cimetidine Amprenavir, Atazanavir, efavirenz, indinavir, lopinavir, nelfinavir, nevirapine, ritonavir, saquinavir and tipranavir d5-Saquinavir d6-indonavir 13C-efavirenz and dibenzipine Abacivir, lamivudine, zidovudine, tenofovir, emtricitabine, didanosine and stavudine 6p-Hydroxy-theophylline Darunavir, etravirine, maraviroc, raletegravir and ritonavir D9-Darunavir Emtricitabine and tenofovir 13C15N-isoemtricitabine and 13C-isotenofovir Amprenavir, atazanavir, lopinavir, ritonavir, nevirapine, darunavir, etravirine and rilpirivine Quinoxalone Amprenavir, lopinavir, ritonavir, saquinavir, tipranavir A86093 Amprenavir, atazanvir, efavirenz, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, tipranavir d5-Atazanavir d6-indinavir d5-saquinavir 13C-ritonavir, d8-lopinavir, d4-efavirenz Ribavirin 13C5-ribavirin Ribavirin Bamethan Ribavirin Acyclovir Ribavirin and viramidine 13C-ribavirin 13C-viramidine Ganciclovir (G) and valganciclovir (V) d5-Ganciclovir and d5-valganciclovir Ganciclovir and valganciclovir Acyclovir and valaciclovir The present invention may also be used to quantify bodily fluid levels (e.g., blood levels) of anticonvulsants. Such anticonvulsants may be selected from the list presented in the Table 3. below, with this table showing suitable Internal Standards that may be 5 incorporated into the composition for analysing the anticonvulsant. Table 3. Examples of anticonvulsants drugs and used Internal Standards. Drug Internal Standard Gabapentin Metformin Gabapentin 1,1,cyclo-Hexane diacetic acid monoamide Gabapentin (S)-(a)-amino-cyclohexane-propionic acid hydrate Gabapentin Acetaminophen Carbamazepine 2-Methyl carbamazepine Carbamazepine Nitrazepam Ethosuximide Pravastatin Lamotrigine 13C2, 15N-LTG Lamotrigine 3,5-Diamino-6-(2-methoxyphenyl)-l,2,4-triazine Levetiracetam UCB17025 Levetiracetam Ritonavir Levetiracetam Adenosine Levetiracetam Ritonavir Levetiracetam Clonazepam Oxcarbazepine Impiramine Oxcarbazepine Cyheptamide Oxcarbazepine dlO-Carba mazepine Oxcarbazepine d3-Trimipramine Phenobarbital o-Acetamidophenol Phenytoin Phenacetin Free phenytoin Phenobarbital Primidone None Topiramate dl2-To pi ramate Topiramate Amlodipine Topiramate Prednisone Topiramate dl2-To pi ramate Topiramate l,2:3,4-bis-o-(l-Methylethylidene-a-D-ga lactopyranose Sulfamate Topiramate None Valproate Betamethasone valerate Valproate Benzoic acid Valproate None Pregabilin Rosuvastatin 10 The present invention may also be used to quantify bodily fluid levels (e.g., blood levels) of antidepressants. Such antidepressants may be selected from the list presented in Table 4. below, with this table showing suitable Internal Standards that may be incorporated into the composition for analysing the antidepressant. Table 4. Examples of antidepressants drugs and used Internal Standards. Drug Internal Standard Amisulpride d5-Amisulpride Amisulpride Eticlopride Aripiprazole Papaverine Aripiprazole OPC 14714 Citalopram Desipramine Citalopram Imipramine Clozapine Mirtazepine Clozapine Congener of risperidone Doxepin Benzoctamine-HCI Duloxetine Haloperidol Escitalopram Paroxetine Fluoxetine Metronidazole Fluoxetine Methylfluoxetine Fluoxetine d2-Fluoxetine Fluoxetine Oxazepam Fluoxetine Desipramine Flupentixol Mosapride Haloperidol Chlorohaloperidol Mianserin Cinnarizine Mirtazepine Haloperidol Moclobemide R011-9900 Nortriptyline d4-Nortriptyline Olanzapine d3-Olanzapine Olanzapine Loratadine Olanzapine LY170158 Olanzapine 2-Ethyl-4-(4-methyl-I-piperazinyl)-10H-thieno[2,3-b] [l,5]benzo-diazepine) Olanzapine LY170222 Paroxetine d5- Fentanyl Paroxetine Pholedrine Paroxetine Fluoxetine Pimozide Cinnarizine Prochlorperazine Amitryptiline-HCI Quetiapine 13C6-quetiapine Quetiapine Clozapine-HCI Quetiapine Clozapine Risperidone d2-13C2-risperidone Risperidone Methyl risperidone Risperidone R 68808 Sertraline Fluoxetine Sertraline Diphenhydramine Sertraline Imipramine Trazodone Nefazodone Tryptophan d5-Tryprophan Tryptophan None used Venlafaxine Verapamil Venlafaxine Fluoxetine Venlafaxine Nadolol Venlafaxine Clozapine Venlafaxine Estazolam Venlafaxine Sildenafil Venlafaxine Escitalopram Zuclopenthixol Flupenthixol The present invention may also be used to quantify bodily fluid levels (e.g., blood levels) of anticancer drugs. Such anticancer drugs may be selected from the list presented in Table 5. below, with this table showing suitable Internal Standards that may be 5 incorporated into the composition for analysing the anticancer drug. Table 5. Examples of anticancer drugs and used Internal Standards. Drug Internal Standard Aromatase inhibitors None Busulfan D8-Busulfan Busulfan Structural analogue Busulfan l,6-bis-(Methanesulfonyloxy)hexane Busulfan d8-Busulfan Cisplatin None Ifosfamide None Epirubicin Doxorubicin Erlotinib, gefitinib and imatinib d8-Imatinib Imatinib d8-Imatinib Imatinib, dasatinib and nilotinib Quinoxaline Irinotecan Camptothecin Lapatinib D6-Lapatinib Lenalidomide and flavopiridol Genistein Melphalan N-phenyldiethanolamine Methotrexate Methotrexate-gamma-(2-hydroxy)ethyl-amide Mycophenolate N-phthaloyl-L-phenylalanine Mycophenolate Indomethacin Nilotinib [13C2, 15N2]-nilotinib Paclitaxel 13C6-paclitaxel Paclitaxel d5-Paclitaxel Doxorubicin Daunorubicin Docetaxel and paclitaxel Cephalomannine Paclitaxel 13C6-paclitaxel Paclitaxel Paclitaxel analogue Docetaxel and paclitaxel Paclitaxel (D) Docetaxel (P) Paclitaxel None Paclitaxel Methyl paclitaxel Pemetrexed Dampa Carboplatin None Procarbazine 3-Dimethylamino-2-methylpropiophenonoe Palbociclib None Ribociclib None Abemaciclib None Ralitritrexed Benazeprilat Sorafenib d3-13C-sorafenib Sunitinib Clozapine Tamoxifen d5-Tamoxifen Tegafur Strychnine Tegafur and 5-fluorouracil 5-Chlorouracil Thalidomide Thalidomide analogue Cyclophosphamide and thiotepa Hexamethyl-phosphoramide All-trans retinoic add Acitretin Vincristine Vinblastine Vincristine and actinomycin-D Vinorelbine Vincristine and actinomycin-D Vinorelbine (V) 7-Amino-actinomycin-D(A) Vincristine and vinblastine Vinorelbine Common pharmaceuticals and drugs of abuse that may be analysed using the apparatus / vessel of the present invention may be selected from the list consisting of Alprazolam (Diazepam-D5), Amitriptyline (Mianserin-D3), Amphetamine (Amphetamine-D5), Benzoylecgonine (Amphetamine-D5), Bromazepam (Diazepam-D5), Buprenorphine (Methadone-D3), Chlordiazepoxide (Diazepam-D5), Chlorprothixene (Mianserin-D3), Citalopram (Mianserin-D3). Clonazepam (Diazepam-D5), 7-Aminoclonazepam (Diazepam-DS), Clozapine (Mianserin-D3), Cocaine (Methadone-D3), Codeine (Methadone-D3), Diazepam (Diazepam-D5), Flunitrazepam (Diazepam-D5), 7-Aminoflunitrazepam (Diazepam-D5), Fluoxetine (Mianserin-D3), Ketamine (Amphetamine-D5), Ketobemidone (Amphetamine-D5), Lamotrigine (Mianserin-D3), Levomepromazine (Mianserin-D3), Lidocaine (Mianserin-D3), Lorazepam (Diazepam-D5), 6-MAM (Amphetamine-D5), MDA (Amphetamine-D5), MDEA (Amphetamine-D5), MDMA (Amphetamine-D5), Methamphetamine (Amphetamine-D5), Methadone (Methadone-D3), Metoclopramide (Dibenzepine), Metoprolol (Mianserin-D3), Mianserin (Mianserin-D3), Mirtazapine (Mianserin-D3), Morphine (Methadone-D3), Nitrazepam (Diazepam-D5),7-Aminonitrazepam (Diazepam-D5), Norfluoxetine (Dibenzepine), Nortriptyline (Mianserin-DS), Orphenadrine (Mianserin-D3), Oxazepam Diazepam-D5), Oxycodone (Dibenzepine), Paroxetine (Dibenzepine), Promethazine (Mianserin-D3), Quetiapine (Mianserin-D3), Sertraline (Dibenzepine) Tramadol (Mianserin-D3), Triazolam (Diazepam-D5),Venlafaxine (Mianserin-D3), Zaleplon (Methadone-D3), and combinations thereof. The apparatus / vessel of the present invention may also be used to sample bodily fluid levels of controlled substances such as narcotics and stimulants, such as controlled substances selected from the list consisting of heroin, marijuana, LSD, codeine, fentanyl, hydrocodone, hydrocodone combinations (e.g., with acetaminophen), hydromorphone, morphine, methadone, oxycodone, oxycodone combinations (e.g., with acetaminophen) tapentadol, amphetamine, methamphetamine and methylphenidate, cocaine, pentobarbital, secobarbital, buprenorphine, dronabinol, ketamine, tramadol, alprazolam, diazepam, clonazepam, lorazepam, midazolam, and combinations thereof. In addition to measuring fluid levels of active pharmaceutical ingredients, the apparatus / vessel of the invention may also be for use in the diagnosis of diseases or conditions by, for example, measuring certain target compounds in bodily fluid samples indicative of those diseases. For example, the apparatus / vessel of the invention may be for use in diagnosing a disease or condition selected from the list consisting of addiction (for example drug addiction or alcoholism), cancer (such as breast cancer or prostate cancer), cardiovascular diseases, high blood pressure, viral infections, fungal infections, bacterial infections, epilepsy, depression, pain, vitamin deficiency, immune-deficiency and steroid deficiency. Rather than having an end cap separate to the sample vessel for the end user to construct, the apparatus may already comprise a sample vessel coupled to the end cap. The sample vessel may contain an analysis solution, which may also be referred to as an extraction fluid or solution. Such an analysis / extraction solution may comprise chemicals that increases the stability of the target molecules enabling cold chain free transports. Chemicals may also be added to pre-process the sample by enriching target molecules or to further lower the time of handling at the lab. Known methods to preserve analytes in samples are precipitation with water miscible solvents such as acetone, 1-butanol, 2-butanol, 2-metyl-l-propanol, 2-metyl-2-propanol, dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, dimethylpropyleneurea, sulfonate. Preservation by "salting out" principle obtained e.g., by ammonium sulfate, and by magnesium sulfate and by saltingout assisted liquid / liquid extraction with acetonitrile. Chemicals acting as pH modifiers e.g., acids such as formic acid, trifluoro acetic acid, acetic acid, by trichloroacetic acid (10-20%), trichloroacetic acid in acetone, ammonium acetate in methanol. Bases such as ammonia, tris(hydroxymethyl)aminomethane, triethylamine and non-nucleophilic amines e.g., N,N-Diisopropylethylamine, l,8-Diazabicycloundec-7-ene, 1,5-Diazabicyclo(4.3.0)non-5-ene, 2,6-Di-tert-butylpyridine, and buffers e.g., the amines exemplified above being 10-90% protonated with e.g., hydrochloric acid, Ammonium acetate, Phosphate-buffered saline, tris EDTA buffer, Britton-Robinson buffer, 2,2'-[(2-amino-2-oxoethyl)azanediyl]diacetic acid, N-(2-Acetamido)-2-aminoethanesulfonic acid, HEPES, HEPBS and HEPPPS. The use of the apparatus or sample vessel according to the invention may follow a method comprising the steps of: a. providing a sampler comprising a fluid sample; and b. introducing the sampler into the interior of the sample vessel so as to introduce the sample to the interior of the sample vessel concurrently with the composition comprising a substance suitable for use as an Internal Standard. According to a further aspect of the invention there is provided a method for analysing, quantifying and / or qualifying the presence and / or concentration of a target compound in a fluid sample from a subject, which method comprises the steps of: providing a kit-of-parts for sampling a fluid as defined above; distributing the kit-of-parts to a location of the subject; receiving a sample vessel comprising a fluid sample with the end cap coupled to the sample vessel; processing and analysing the sample to determine the concentration of the target compound and the Internal Standard; and calculating the concentration of the target compound in the fluid sample at the time of sampling. The processing step may include a step of centrifuging the sample in order to remove proteins and / or polar chemicals in the sample. In any aspect of the invention, the sample may be analysed by any means known in the art that would be suitable to calculate the concentration of the target compound in the sample. For example, the sample may be analysed using liquid chromatography single or tandem mass spectrometry such as (LC-MS / MS), mass spectrometry (MS / MS), or gas chromatography (GC-MS / MS). The apparatus may be produced according to regulatory guidelines. The apparatus can be sold directly to the customer online or in pharmacies or given to the end customer at a healthcare facility with instructions on how to use it. The customer / patient may be provided with the apparatus in a box containing instructions for the sampling procedure, including the following items which may be included in the kit-of-parts as defined herein and used according to the following method: 1: Small sterilisation towel to sterilise the area that will be punctured; 2. A lancet to puncture the skin, e.g., fingertip; 3. A capillary to collect a specified exact amount of blood, preferably 20-50 uL; 4. A plaster; 5. The device (fluid sample collector) may be marked with a specific and unique barcode and a digital or analogue solution to mark the date and time of sampling; 6. A envelope pre-addressed and prepaid envelope for posting to a laboratory; 7. The results will be returned to the customer registered for that unique barcode (the patient or a health care institution). With regard to point 5, the apparatus of the invention may be identified with a unique marking, e.g., barcode, which identifies the sample for onward analysis. Brief Description of the Figures Figure 1 shows a side cross-sectional view of an end cap according to the invention. Figure 2 shows an aerial view of the end cap of figure 1. Figure 3 shows a side, non-cross-sectional view of the end cap of figures 1 and 2. Figure 4 shows a series of depictions of an embodiment of how the device according to the invention is used, with figure 4A showing the sampler and the sample vessel separate to one another, figure 4B showing the sampler extending through the aperture of the end cap, and figure 5C showing the sample holder coupled to the end cap. Figure 5A to 5E shows a series of depictions of another embodiment of how the device according to the invention is used, with figures 5A to 5C showing how a syringe and plunger sampler is used with a sample vessel coupled to an end cap according to the invention, and figures 5D and 5E showing how the end cap can be coupled to a lid after sample introduction. Detailed Description of the Figures and the Invention Specific embodiments of the invention will now be described with reference to the accompanying figures. Figure 1 shows a side profile cross-sectional view of an end cap (100) according to the present invention. The end cap (100) comprises an aperture (102) in which a dry pellet (104) is positioned. The dry pellet contains a substance suitable for use as an Internal Standard. The dry pellet (104) is sealed on both sides of the aperture (102) by penetrable films (106). The end cap (100) has two sets of threads, one at the lower portion (108) for coupling to a sample vessel and another set at the upper portion (110) for coupling to a lid or sampler handle. Figure 2 shows an upper profile view of the end cap (100) of Figure 1 with the center showing the aperture (102). On this end cap (100) the outer section (112) has a series of ridges for ease of user handling. Figure 3 shows a side profile non-cross-sectional view of the end cap of figure 1. Here the upper threading portion (110) can be more clearly seen. Figures 4A, 4B and 4C shows an embodiment of the invention. When in use the user provides a fluid sample for analysis. The fluid sample may be provided by any means, such as by use of a lancet for drawing blood via a finger prick. On the fluid (e.g. blood) being provided, the user grasps the sampler (200) by the handle portion (202) and dips the exposed end of the sampler (204), in this case a capillary tube, into the blood sample. On doing so the capillary draws up a defined amount of blood sample. Following this, the user takes a sample vessel (300), which has been coupled to the end cap (100) and advances the capillary tube (204) through the aperture thus penetrating the upper film and pushing the dry pellet (104) through the lower film and exposing the dry pellet to the interior of the sample vessel (300). The sample vessel (300) contains an analysis / extraction solution (302), which is shown in Figure 4B, and on penetrating the lower film (106) the dry pellet (104) drops into the analysis / extraction solution (302) and releases the substance suitable for use as an Internal Standard into the solution. Simultaneously the user advances the capillary tube (204) fully into the sample vessel (300) and contacts the end of the capillary tube with the analysis / extraction solution (302). On doing so the blood sample is contacted with the analysis / extraction solution concurrently with the dry pellet (104). On full advancement of the capillary tube (204) into the sample vessel (300) the handle portion (202) of the sampler (200) is then screw fit onto the top of the end cap for storage. Figures 5A, 5B, 5C, 5D and 5E show an alternative embodiment of the invention. In this embodiment, when in use the user provides a fluid sample for analysis. The fluid sample may be provided by any means, such as by use of a lancet for drawing blood via a finger prick. On the fluid (e.g. blood) being provided, the user grasps the sampler (400), which in this embodiment is in the form of a syringe (402) with a plunger (404), and draws up the blood sample into the syringe (402) by withdrawing the plunger (404). In this embodiment the syringe may comprise volume markings so that the user can draw up a determined amount of fluid (e.g., blood). Following this, the user takes a sample vessel (300), which has been coupled to the end cap (100) and advances the end of the syringe (402) through the aperture (102) thus penetrating the upper film and pushing the dry pellet (104) through the lower film and exposing the dry pellet to the interior of the sample vessel (300). The sample vessel (300) contains an analysis / extraction solution (302), which is shown in Figure 4B, and on penetrating the lower film (106) the dry pellet (104) drops into the analysis / extraction solution (302) and releases the substance suitable for use as an Internal Standard into the solution. Simultaneously the user presses the plunger (404) on the syringe (402) to expel the fluid sample into the interior of the sample vessel (300). When the fluid sample is fully expelled from the syringe, the user may withdraw the syringe out of the end cap aperture (102) and fit a lid (500) onto the top of the end cap (100) to close the apparatus. Once the sample and substance suitable for use as an Internal Standard have been contacted with the analysis / extraction solution the apparatus is closed and further analysis of the target compounds can be pursued. For example, analysis of the target compounds can be performed by any means known in the art, such as liquid chromatography mass / mass spectrometry (LC-MS / MS). With the fluid sample and the substance suitable for use as an Internal Standard contacting the analysis / extraction solution concurrently, and with the substance suitable for use as an Internal Standard having been previously protected from degradation in the apparatus, the target compound and the Internal Standard will degrade at the same rate. With the mass of Internal Standard being known prior to contacting the analysis / extraction solution, the concentration of the target compound in the fluid sample at the time of taking the sample can, therefore, be back calculated. Therefore, the apparatus of the present invention provides a number of advantages, including: 5 • ease of use not necessarily requiring a trained medical practitioner, meaning that users may self-sample; • accurate analysis of levels of target compounds in fluid samples with reliability not affected by processing delays; and • reduce costs due to the users being able to self-sample and not being located in a 10 clinical setting to do so.

Claims

1. A fluid sample collection apparatus comprising an end cap, a sample vessel comprising an analysis / extraction solution, and a sampler configured to sample a defined volume of sample fluid, wherein the sampler has a handle portion, wherein the end cap comprises a composition comprising a substance suitable for use as an Internal Standard, wherein the composition is sealed within the end cap in an atmosphere that protects the substance suitable for use as an Internal Standard from degradation and wherein the end cap is reversibly coupled to the sample vessel and configured to controllably release the composition to the interior of the sample vessel, wherein the composition is a matrix composition comprising a polymeric stationary phase that retains the Internal Standard by hydrophobic interactions, wherein the end cap comprises an aperture for receiving the sampler with the composition being positioned within the aperture and wherein the end cap is configured to release the composition into the interior of the sample vessel by introducing the sampler through the aperture, wherein the composition is sealed on both sides of the aperture by an upper and a lower penetrable film, such that on the sampler being introduced through the aperture the penetrable films are broken resulting in the composition being released into the interior of the sample vessel, wherein the apparatus further comprises a lid that is reversibly couplable to the end cap.

2. The fluid sample collection apparatus according to Claim 1, wherein the polymeric stationary phase comprises aliphatic groups.

3. The fluid sample collection apparatus according to Claim 2, wherein the aliphatic groups are C1-C18 chains, phenyl or diphenyl groups.

4. The fluid sample collection apparatus according to any preceding claim, wherein the polymeric stationary phase is modified with polar groups.

5. The fluid sample collection apparatus according to Claim 4, wherein the polar groups are aromatic or aliphatic hydroxyl groups, or aromatic or aliphatic amines.

6. The fluid sample collection apparatus according to any preceding claim, wherein the matrix composition comprises polypropylene, polyethylene or polyamide.

7. The fluid sample collection apparatus according to any preceding claim, wherein the matrix composition comprises a cosolvent.

8. The fluid sample collection apparatus according to any preceding claim, wherein the matrix composition comprises a solid phase that is soluble in the analysis / extraction solution.

9. The fluid sample collection apparatus according to any preceding claim, wherein the matrix composition comprises scavengers configured to further increase the stability of the Internal Standard.

10. The fluid sample collection apparatus according to any preceding claim, wherein the composition is a dry pellet.

11. The fluid sample collection apparatus according to Claim 10, wherein the end of the dry pellet that is towards the lower penetrable film is shaped to a tapered point.

12. A kit-of-parts comprising a plurality of sample vessels comprising an analysis / extraction solution according to any one of Claims 1 to 11, a plurality of samplers according to any one of Claims 1 to 11, a plurality of lids according to any one of Claims 1 to 11 and a plurality of end caps according to any one of Claims 1 to 11, wherein the sample vessels and end caps are configured to be reversibly couplable together.

13. The kit-of-parts according to Claim 12, further comprising a lancet.

14. A method of using a kit-of-parts according to Claims 12 or 13, wherein the method comprises the steps of:a. providing one of the samplers comprising a fluid sample; andb. introducing the sampler into the interior of one of the sample vessels so as to contact the fluid sample with the analysis / extraction solution and concurrently releasing the composition into the interior of the sample vessel.

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