Microplastic standard reference material (MP-SRM)

Abstract

A Microplastic Standard Reference Material (MP-SRM) designed to enhance the accuracy and reliability of microplastic (MP) analysis in environmental science. The MP-SRM comprises an effervescent tablet

Description

Field of the Disclosure [1] The present disclosure pertains to the field of environmental science, specifically the identification and quantification of microplastics (MPs) in environmental samples. More particularly, the present disclosure relates to the creation of a Microplastic Standard Reference Material (MP-SRM) designed to enhance the accuracy, consistency, and reliability of MP analysis procedures by including microplastics from waste streams, which are the major contributors of microplastics in the environment. The rationale for using MPs from waste streams is based on the fact that it is often degraded and is similar to MPs found in environmental samples. Background [2] PIastic pollution, particularly in the form of microplastics (MPs), has emerged as a global environmental challenge. MPs are minute plastic particles with dimensions typically ranging from 1 pm to 5 mm, and they result from the fragmentation of larger plastic items, as well as the direct release of small plastic particles into the environment. These particles have infiltrated various ecosystems, including aquatic environments, terrestrial ecosystems, and even the atmosphere. [3] The ubiquitous presence of MPs in the environment is a matter of increasing concern due to their potential adverse impacts on ecosystems, wildlife, and human health. MPs can be ingested by aquatic organisms, subsequently entering the food chain and posing risks to both marine and terrestrial organisms, including humans. Ingestion of MPs by marine organisms can lead to physical harm, malnutrition, reproductive disorders, and toxicity due to the chemicals associated with plastics. Furthermore, the propensity of MPs to adsorb and transport hydrophobic contaminants, as well as the leaching of chemicals, adds further complexity to the ecological and environmental risks associated with these particles. [4] The alarming prevalence and persistence of MPs in the environment have spurred significant scientific interest and research worldwide. As of November 2023, a bibliographic search yielded approximately 9,000 articles dedicated to microplastics, reflecting the profound scientific engagement with this issue. The majority of these studies have centred on MPs in the marine environment, with fewer addressing MPs in freshwater ecosystems and fewer even exploring their presence in aerosols. [5] While the scientific community has made substantial progress in documenting the occurrence of MPs in various environmental matrices, such as water, sediments, soil, biota, sludge, and aerosols, several challenges persist. These challenges include the lack of standardized protocols for sample collection, preparation, identification, and reporting units. The absence of standard reference material to assess the accuracy and efficacy of MP determination in environmental samples makes it challenging to ensure the consistency and reliability of the MP results from a study or a laboratory and to cross-compare between different analysis protocols and analysis providers. [6] In any scientific field, the accuracy, reliability and repeatability of analytical data are of paramount importance. In the context of MPs, the precise identification and quantification of these particles are essential for understanding their distribution, ecological impacts, and potential risks to human health. Achieving this level of precision requires standardized procedures and reference materials against which the accuracy of results can be assessed. [7] Currently, most laboratories and analysts rely on sample blanks to assess laboratory contamination, but this provides limited insights into the efficacy of laboratory protocols, operator biases, and errors. The lack of a universally accepted standard reference material similar to MPs in the environment is a much-needed analytical tool to provide insight into the uncertainties in analyses from a laboratory and / or an analyst. Researchers have grappled with variations in sample preparation techniques, density separation methods, and identification procedures, leading to disparities in reported results. [8] Accordingly, it is desirable to provide a Microplastic Standard Reference Material (MP-SRM) that overcomes the limitations of non-existing reference materials and offers a comprehensive solution for enhancing the accuracy, consistency, and reliability of microplastic (MP) analysis in environmental samples. In particular, it would be desirable to introduce an MP-SRM that accurately replicates the diversity of MP characteristics found in real-world samples, while also simulating their behaviour during density separation and flotation processes. The products and methods described herein should enable analysts to systematically assess the accuracy of laboratory procedures, identify and quantify potential errors and biases introduced at various stages of MP analysis, and ultimately contribute to the reliability of MP results for pollution assessment, pollution control, and regulatory efforts aimed at mitigating the global issue of plastic pollution. Summary of the Disclosure [9] In a first aspect, a Microplastic Standard Reference Material (MP-SRM) is provided comprising an effervescent tablet, said tablet containing a predetermined quantity of microplastic particles varying in one or any combination of two or more of: shapes, sizes, and polymer types.

[10] In embodiments, the tablet is between 10mm and 100mm along a major axis, such as diameter or length, extending parallel to opposed parallel surfaces and between 5mm and 50mm in thickness between the opposed parallel surfaces.

[11] In embodiments, the microplastic particles within the tablet range in size from 1 pm to 5000 pm, optionally 10 pm to 3000 pm.

[12] In embodiments, the microplastic particles within the tablet include at least one of: primary microplastics manufactured for incorporation into products and secondary microplastics resulting from the breakdown of larger plastic debris.

[13] In embodiments, the microplastic particles within the tablet are of various polymer types, optionally including any combination of two or more of: polyethylene, polypropylene, polyethylene terephthalate, and polystyrene.

[14] In embodiments, the tablet is suitable for serving as a reference material for assessing the accuracy and efficacy of microplastic analysis procedures.

[15] In another aspect, a method for assessing the accuracy of microplastic analysis procedures is provided, comprising the steps of dissolving the MP-SRM of any preceding claim in a solution used for density separation, and subsequently processing the solution using microplastic analysis techniques.

[16] In embodiments, the method further comprises the step of comparing the results obtained from the microplastics analysis techniques with known characteristics of the microplastic particles within the tablet to identify errors.

[17] In embodiments, the method further comprises quantifying the identified errors based on the comparing.

[18] In embodiments, the comparing is performed by at least one processor executing computer program instructions.

[19] In another aspect, a method for producing the Microplastic Standard Reference Material (MP-SRM) is provided, comprising the steps of segregating microplastic particles from environmental samples, analysing the segregated microplastic particles to determine characteristics of the microplastic particles, providing reference data representing the determined characteristics and incorporating the segregated microplastic particles into an effervescent tablet using at least a binding agent.

[20] In embodiments, the reference data is provided as a digital file and / or in hardcopy.

[21] In a further aspect, a packaged MP-SRM tablet is provided. The package and / or the MP-SRM tablet includes reference data characterizing the microplastic particles in one or any combination of two or more of: shapes, sizes, and polymer types or wherein the reference data is associated with the package or the tablet in the form of an identifier or a link to the reference data included in a server or other remotely accessible computer.

[22] In embodiments a server or remotely accessible computer is included having the reference data stored on memory thereof.

[23] Described herein is a Microplastic Standard Reference Material (MP-SRM) that addresses a need for standardized reference materials to enhance the accuracy and reliability of microplastic assessments in diverse environmental matrices. MP-SRM is an effervescent tablet designed with meticulous attention to detail, encapsulating a variety (e.g. greater than 100) of microplastic particles of varying sizes, shapes, and polymer types. The tablet may be sized to have a volume of, for example, between 1ml (or 1cm3) and 50 ml (50 cm3). The tablet exhibits effervescent properties, so when added to the solution, will release the MPs encapsulated within and particles floating in solution mimicking the behaviour of real-world microplastics during density separation and flotation processes.

[24] The MP-SRM serves as an invaluable tool for analysts, laboratories, and organizations engaged in microplastic analysis. By dissolving the tablet in media (the same media that will be used for environmental samples) and analyzing the results, researchers can assess the efficacy of their laboratory protocols, identify the scale of error, and quantify biases introduced at different stages of the analysis process. This standardized reference material offers a practical means to evaluate the accuracy of microplastic determination, identify uncertainties (both from method and operator) and enhance the reproducibility of results. MP-SRM's versatility enables its use across a wide range of environmental samples, including seawater, sediment, soil, biota, sludge and aerosols.

[25] The MP-SRM is crafted to comprehensively represent the diverse nature of microplastics in the environment. The tablet's composition—featuring a range of microplastics from 1 to 5000 pm or 10 to 3000 pm—enables it to accurately simulate the variety of microplastics typically encountered in environmental samples. This range includes both primary and secondary microplastics, reflecting the current state of pollution across various ecosystems. The tablet's formulation is designed to ensure a consistent and homogenous distribution of these particles, guaranteeing reliability and consistency in every analysis.

[26] The significance of the MP-SRM extends beyond analysis accuracy. By providing a standardized benchmark, facilitating assessment of analytical bias in reported results and making comparative studies across different regions and time periods more realistic, thus contributing to a broader understanding of microplastic pollution patterns globally. This standardized reference can be instrumental in ensuring the reliability of data in evaluating the effectiveness of pollution control measures and in guiding policy decisions. Furthermore, it enhances the confidence within the scientific community's capacity to conduct longitudinal studies, tracking the progression and impact of microplastic pollution reliably overtime.

[27] The MP-SRM is a crucial step towards addressing the global environmental challenge of microplastic pollution. It not only empowers researchers and environmental scientists with a tool for accurate assessment but also provides industries, regulators, and policymakers with the reliable data needed to formulate effective strategies for managing and mitigating plastic pollution. As the concern over microplastic pollution grows, the MP-SRM stands as a key enabler for data quality that is key in advancing research, informing policy, and fostering global environmental stewardship in the face of this pervasive data quality issue.

[28] Other aspects and features of the present disclosure will become apparent, to those ordinarily skilled in the art, upon review of the following description of the various embodiments of the disclosure. Brief Description of the Drawings

[29] Embodiments will now be described with reference to the attached drawings in which: FIG. 1 shows a functional block diagram of a microplastics analysis evaluation system using an MP-SRM tablet, in accordance with an embodiment of the disclosure; FIG. 2 shows a flowchart for a method of using the MP-SRM tablet, in accordance with the present disclosure; and FIG. 3 shows a flowchart for a method of using the MP-SRM tablet, in accordance with the present disclosure. Detailed Description of Embodiments

[30] It should be understood at the outset that although illustrative implementations of one or more embodiments of the present disclosure are provided below, the disclosed systems and / or methods may be implemented using any number of techniques. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[31] FIG. 1 provides a functional block diagram of a microplastics analysis evaluation system 24 that includes an MP-SRM tablet 10, to be added to a blank solution at sample preparation stage 12, an MPs separation and analysis stage 16 and a performance evaluation stage 22. The MP-SRM tablet 10 is associated with reference data 18, which is a result of analysis during production of the MP-SRM tablet 10. The MP-SRM tablet 10 is mixed with the filtered solution at sample preparation stage 12 to provide the sample 26. The MPs separation and analysis stage analyses solution 16 to provide the analysis data 20. The reference data 18 and the analysis data 20 are compared in the performance evaluation stage 22 to produce a findings report 28.

[32] In one exemplary embodiment, the MP-SRM tablet 10 is constructed from a mixture of sodium bicarbonate, citric acid, and glycocol. Alternatives to these materials could include other biodegradable binding and effervescent agents. In the exemplary embodiment where the MP-SRM tablet 10 is made from a mixture of sodium bicarbonate, citric acid, and glycocoll, alternative compositions can be considered to achieve similar effervescent and binding properties while maintaining biodegradability. Alternative compositions can include sodium bicarbonate and tartaric acid. The sodium bicarbonate: can act as a base and is a component for effervescence. When combined with an acid in the presence of water, it releases carbon dioxide, causing the effervescence. Tartaric acid is an organic acid that can react with the sodium bicarbonate to produce the effervescent effect. Tartaric acid is biodegradable and commonly used in food and pharmaceutical products. Gelatin or Agar-Agar are natural binders and can be used as an alternative binding agent to glycocoll. These substances are biodegradable and help in forming a cohesive tablet structure. In another alternative composition, potassium bicarbonate and citric acid can be combined. The potassium bicarbonate provides alternative to sodium bicarbonate and acts similarly as a base and effervescent agent. Potassium bicarbonate is often used in organic farming. Citric acid provides effective acidic properties that contribute to the effervescent reaction. These alternative compositions maintain the characteristics of an effervescent tablet - the ability to dissolve rapidly in water while releasing microplastics. The choice of alternative materials should consider the environmental impact, biodegradability, and the interaction of these materials with the encapsulated microplastics to ensure they do not alter the properties of the microplastics in the MP-SRM tablet 10.

[33] In this example, the MP-SRM tablet measures 30 mm in diameter and 8 mm in thickness. The MP-SRM tablet 10 contains 150 microplastic particles, ranging in size from 10 to 3000 pm, in various shapes, colours, and / or polymer types. The MP-SRM tablet 10 composition simulates real-world environmental microplastic samples, including both primary and secondary MPs. When considering alternative specifications for the MP-SRM tablet 10 in terms of size, shape, number of microplastic particles, and size ranges of these particles, it is important to ensure that these alternatives still effectively serve the purpose of standardizing and evaluating microplastic analysis methods. The diameter (or other longest axis for non-cylindrical tablets extending parallel to opposed surfaces of the tablet where those opposed surfaces are separated by tablet thickness) can be 20 mm to 50 mm in some exemplary alternatives. The thickness can be 5 mm to 12 mm in some exemplary alternatives. These ranges accommodate different analysis equipment and testing scenarios, ensuring the tablet can be used in a variety of settings. The MP-SRM tablet is generally cylindrical in one embodiment but may also be spherical (with diameter range as described above), have oval or elliptical opposed major surfaces (separated by the thickness) or oblong or any other shape. Different shapes may offer a different dissolution profile, which might be useful in certain experimental setups. The number of microplastics included in the MP-SRM tablet may range from 100 to 300 particles per tablet. This range offers flexibility, allowing for tablets to be tailored to specific research needs or analysis sensitivities. The microplastics may range in size from 1 pm to 5000 pm. The MP-SRM tablet 10 may include microplastics in each of the following size ranges, or any combination of two of the following size ranges: large microplastics (size range - greater than 1 mm and up to 5 mm), medium microplastics (size range - between 1000 pm (1mm) and 100 pm (0.1 mm) and smaller microplastics (size range: Less than 100 pm (0.1 mm), going down to 1pm). These size ranges allow the MP-SRM tablet 10 to simulate a wide variety of environmental microplastic conditions, accommodating different research focuses and methodologies.

[34] The chosen size of the MP-SRM, shape, number, and size range of microplastics should align with the intended application and testing requirements. For instance, larger tablets or more particles might be useful in high-volume testing scenarios. The size and shape of the tablet can influence its dissolution rate, which is crucial for releasing microplastics in a controlled and predictable manner. The size range and quantity of microplastics should adequately represent the environmental conditions being simulated, ensuring the relevance and applicability of the analysis. The tablet's physical properties should be compatible with standard laboratory equipment used in microplastics analysis.

[35] The MP-SRM tablet 10 is associated with reference data 18. Accompanying the MP-SRM tablet 10, the reference data 18 includes detailed information on the size, shape, polymer type, and quantity of microplastic particles in the MP-SRM tablet 10. The quantity of microplastics may be provided for each of a plurality of size ranges such as the size ranges described above including large microplastics, medium and small microplastics. A greater number of non-overlapping size bins may be provided in the reference data 18. This reference data 18 can be in digital or hardcopy format and is crucial for subsequent performance evaluation.

[36] The MP-SRM tablet 10 can be manufactured according to a more detailed description provided with reference to FIG. 3. In one exemplary embodiment, microplastics are collected from environmental sources such as wastewater influent and / or sludge samples. The collection may involve using amber glass bottles for water samples and wide-mouth glass jars for sludge, ensuring minimal contamination. The collected samples undergo processes like organic matter oxidation using potassium hydroxide and heating at controlled temperatures (around 40 °C). Vacuum filtration systems with Silver membrane filters (0.45 pm pore size) may be used and density separation setups using KI or ZnCl2 solution may be employed. Segregated microplastics are stained (e.g., with Nile Red), and identified using UV-stereomicroscopy and micro-Raman spectroscopy. Sizes, shapes, and polymer types are meticulously recorded for the reference data 18. Advanced microscopes and spectroscopy units may utilized for accurate characterization. The separated microplastics are formulated into a tablet and compacted. In one example, a blend of sodium bicarbonate, citric acid, and glycocoll (or other biodegradable binders) is mixed with the characterized microplastics. The mixture is then compacted into tablets of specified size (e.g., 30 mm diameter, 8 mm thickness). Standard pharmaceutical-grade tablet compaction machinery may be used for uniform tablet formation. Each batch of tablets may undergo quality control to ensure consistent microplastic content and tablet integrity.

[37] During manufacturing, detailed data about each batch of MP-SRM tablets is compiled. This includes the count, size range (e.g., 10 to 3000 pm), shape and polymer type of microplastics in each tablet. The count may be distributed across plural (e.g. 3, 4, 5, or more) size bins. This data is documented in a standardized format as the reference data 18. The reference data 18 is then associated with individual tablet batches, either through direct inclusion in packaging, unique identification numbers, QR codes, or digital links. Data management systems and software may be utilized to link each tablet batch (or individual tablet) to its corresponding reference data seamlessly.

[38] The reference data 18 may be associated with the MP-SRM tablet 10 in a variety of ways. For example, the MP-SRM tablet 10 may be packaged and each package of the MP-SRM tablet 10 comes with printed documentation that includes comprehensive reference data 18 about the tablet. This data encompasses details like the size, shape and polymer types of the microplastic particles contained in the tablet, as well as their quantity. In another example, a QR code is printed on the packaging of the MP-SRM tablet. 10 When scanned, this QR code directs the user to a webpage or digital document containing the detailed reference data 18 for the specific batch or tablet. In another example, the MP-SRM tablet 10 package (or the tablet itself by printing, embossing or engraving on a surface of the tablet) may include a unique tablet identification number: Users can enter this number on a designated website or through a digital application to access the corresponding reference data. In another example, a small digital tag or chip, such as an RFID (Radio-Frequency Identification) chip, may be embedded in the tablet's packaging. When scanned with an appropriate device, the device retrieves the tablet's reference data 18 from a secure database. In a further example, a dedicated mobile (or other) application is developed where users can input the tablet’s identification details or scan a code. The application then displays or otherwise outputs the relevant reference data 18. Each tablet's reference data 18 may be securely stored and can be accessed via a blockchain ledger, ensuring data integrity and traceability. In another alternative example, upon purchase or registration of the MP-SRM tablet 10, the user receives an email with attached data sheets or gains access to a secure online portal where the data can be viewed and downloaded.

[39] Continuing to refer to FIG. 1, a clean / filtered solution 14, such as a saturated salt solution (e.g., NaCI, KI, Nai, ZnCI2), is prepared for dissolving the MP-SRM tablet 10. The solution should be same as the one used for environmental samples. Alternative solutions could be used depending on the desired simulation environment. The following exemplary possibilities for the solution 14 are envisaged. A saturated solution of sodium chloride may be used with varying concentrations. A saturated solution ensures adequate density for separating most types of microplastics. Potassium iodide solutions have a higher density compared to sodium chloride, making them effective for separating a wider range of microplastics. Adjustments in concentration can be made to suit specific types of microplastics, especially those with higher densities. Zinc chloride solutions may be used for their high density, which is effective in separating even dense microplastics from environmental samples. The saturated ZnCl2 solutions are preferred for maximum efficacy. Sodium iodide solutions have high density, aiding in the effective separation of microplastics. The density of the solution can be adjusted by varying the concentration of Nai. Ethanol, mixed with water in various proportions, can be used as a less dense alternative, suitable for specific types of microplastics. The ratio of ethanol to water can be altered to achieve the desired density and separation effectiveness. Custom-formulated salt solutions can be used for the solution 14, which use combinations of different salts (e.g., a mix of NaCI and KI) to achieve specific densities tailored to particular microplastic types. The proportions of different salts can be adjusted based on the types of microplastics being analyzed. Isopropanol can be used in varying concentrations for microplastic separation, particularly when working with samples that require gentle treatment. Dilution with water can be adjusted to modulate the density and separation characteristics. Glycerol, due to its higher density and viscosity, can be used either pure or mixed with water. The concentration of glycerol can be varied; higher concentrations are typically used for denser microplastic particles. Each of these solutions 14 offers different characteristics that can be leveraged depending on the types of microplastics being analyzed, the environmental matrix being simulated, and the specific requirements of the analysis procedure. The choice of solution should be guided by the goal of effectively mimicking the conditions in which microplastics are typically found and ensuring the accurate release and separation of microplastics from the MP-SRM tablet.

[40] In the sample preparation stage 12, the MP-SRM tablet 10 is mixed with the solution 14 to prepare the sample 26 for analysis. The MP-SRM tablet 10 is not mixed with an environmental sample. Rather, a separate MP-SRM sample is prepared to be processed in parallel to each batch of environmental samples. Equipment used in this stage may include standard laboratory mixers or shakers. Automated systems could be employed for consistent and reproducible sample preparation. The MP-SRM tablet 10 is introduced into the prepared solution 14. This can be done manually or through an automated dispensing system for consistency. In automated systems, precision dispensers ensure accurate placement of the tablet into the solution. Effervescence occurs when the tablet, composed of ingredients like sodium bicarbonate and citric acid, reacts with the solution. This reaction leads to the release of carbon dioxide gas. The effervescent reaction causes the MP-SRM tablet 10 to dissolve rapidly, ensuring a quick and uniform release of microplastic particles. As the tablet dissolves, the released gas bubbles help to agitate the solution, aiding in the separation of microplastic particles from the tablet's matrix. Following the introduction of the MP-SRM tablet 10, the solution may be gently mixed to ensure even distribution of the microplastics. This can be achieved using a magnetic stirrer, a shaker, or a mechanical mixer. For delicate samples, manual swirling or inversion techniques might be preferred to prevent damage to the microplastics. The dissolution of the MP-SRM tablet 10 and the distribution of microplastics may be monitored, visually or using sensors in automated systems to ensure complete dissolution and even distribution of microplastics.

[41] The MPs separation and analysis stage 16 involves analyzing the solution to identify and quantify MPs. The solution to which the MP-SRM 10 has been added is processed like any other environmental sample in a batch that is being processed so as to be analyzed as a sample with each batch of environment sample to capture any cross contamination in the laboratory and operator’s bias.

[42] Equipment like UV-stereomicroscopes, micro-Raman spectroscopy units, and filtration systems are employed. Automated systems with image analysis software can enhance efficiency and accuracy. In an exemplary embodiment, the MP separation and analysis stage 16 includes performing density separation, which may involve adding a dense medium to the solution to create a density gradient. Microplastics with lower density than the medium float, while heavier components sink. Commonly used separation mediums include saturated solutions of salts like NaCI, ZnCI2, or KI as described with respect to the solution 14 previously. Centrifuges or settling tanks can be used to expedite and enhance the separation process. The separated microplastics are then filtered from the solution 14. This step captures the microplastics on a filter surface for further analysis. Membrane filters with appropriate pore sizes (typically 0.2 to 0.45 micrometers) are used, to ensure all microplastics are captured. In some embodiments, a cascade of filters with reducing pore size is used in order to separate the microplastics into different size ranges. The choice of filter material is important to prevent the adherence or absorption of microplastics onto the filter. Exemplary materials for the filter membrane include glass fiber filters, anodized aluminum oxide (AAO) membrane filters, ceramic membrane filters and silver membrane filters.

[43] The MPs separation and analysis stage includes a step of microplastic identification and quantification. In one example embodiment, microplastics are examined under a microscope post-filtration. Stereomicroscopes or compound microscopes equipped with polarized light can be used for visual identification. In some examples, automated imaging techniques may be used with software capable of recognizing and counting microplastic particles based on size, and shape. Spectroscopic analysis may be performed to determine the chemical composition of the microplastics. Techniques like FTIR (Fourier-Transformed Infrared Spectroscopy) and Raman spectroscopy may be employed. These methods provide information about the polymer types of the microplastics. The information gathered from microscopy and spectroscopy, including the number, size, shape, and polymer type of microplastics, is recorded and output as analysis data 20. Specialized software can be used for data collection, management, and preliminary analysis. This software might include features for statistical analysis and visualization of data. To ensure accuracy, the MP separation and analysis stage 16 may include quality control measures. This might involve comparing results with known standards or conducting repeat analyses. The findings may be validated through parallel analysis using different techniques or repeat experiments to ensure reproducibility and reliability. A final step involves preparing a detailed report of the findings in the form of analysis data, including the concentration and characteristics of microplastics found in the sample. Many aspects of the MPs separation and analysis stage 16, particularly in the identification and quantification of microplastics, are amenable to automation. Advanced systems might incorporate Al (machine learning) algorithms for image analysis, pattern recognition, and data interpretation, further enhancing the efficiency and accuracy of microplastic analysis. It should be understood that the MPs separation and analysis stage 16 in which the MP-SRM 10 is being used may vary in protocols and equipment depending on the analysis stage being evaluated.

[44] Analysis data 28 provides values and labels for the size, shape, polymer type, and quantity of MPs in the sample 26. This analysis data 28 enables comparing with reference data 18 to evaluate the performance of the analysis equipment. The analysis data 20 (like the reference data 18) may include any one or any combination of two or more of the following main data items: Count data (total number of microplastic particles detected in the sample), optional density information (the concentration of microplastics per unit volume or weight of the sample), and size distribution. Size distribution may include one or more of the data items including size range of microplastics found, typically reported in micrometers (pm), category breakdown so that classification of microplastics into size categories (e.g., small microplastics, large microplastics, etc.) is provided and size frequency providing a frequency distribution of different size classes within the sample. The main data items may additionally include shape and type classification including morphology (description of the shapes of microplastic particles (e.g., fibers, fragments, films, beads)) and optionally aspect ratio (measurements of length, width, and possibly depth of particles to determine their shape characteristics). The main data items can include pattern information (e.g., identification of patterns or markings on microplastics that may link them to specific sources). The main data items may include polymer composition including polymer types (identification of the types of polymers the microplastics are composed of (e.g., polyethylene, polypropylene, polystyrene, etc. The main data items may include texture analysis (information on the surface texture of microplastics, which can indicate environmental degradation). The main data items may include degradation state such as weathering indicators (e.g. evidence of physical, chemical, or biological degradation processes that the microplastics have undergone). The main data items may include statistical metrics obtained from application of statistical tools to interpret the data, providing insights into the significance and reliability of the findings. The analysis data 20 may include photographic documentation such as microscopic images or photographs of the microplastics, serving as a visual record and aiding in the verification of the analysis.

[45] The performance evaluation stage 22 includes comparing the analysis data 20 with the reference data 18 to evaluate the efficacy of the MPs analysis process. Manual comparison can be performed, or algorithmic comparison may be conducted. In some embodiments, advanced Al algorithms can be implemented for automatic data comparison and error identification. Al systems could use machine learning techniques to identify patterns and deviations in data more efficiently. The reference data 18, which details the expected characteristics and quantities of microplastics in the MP-SRM tablet 10, is retrieved. This might be through package inserts, digital databases, QR codes, or unique identification numbers associated with the MP-SRM tablet 10. The collected analysis data 20 is methodically compared against the reference data 18. This comparison aims to identify any discrepancies or variations. Key aspects of the comparison step include the efficiency of microplastic recovery, accuracy in sizing and counting, fidelity in shape and color identification, and precision in polymer type determination. Advanced software and analytical tools, potentially incorporating Al and machine learning algorithms, can be used for in-depth data analysis. These tools can handle large datasets, perform statistical analyses, and highlight significant deviations or patterns. The software can automatically flag discrepancies, calculate recovery rates, and provide a detailed analysis of the performance of the analytical methods used. Based on the findings, recommendations for adjustments or improvements in the analysis protocol can be made. A comprehensive report is generated in the form of findings report 28, detailing the outcomes of the performance evaluation. This includes both the successes and any areas of discrepancy. The report may also include suggestions for methodological enhancements or further research needs. A feedback loop may be implemented such that the findings from the performance evaluation stage 22 can feed back into the overall microplastic analysis process (the MPs separation and analysis stage), aiding in the continuous improvement of methodologies and protocols. This feedback loop can be automated whereby settings and protocols of equipment and procedures in the MPs separation and analysis stage is automatically adjusted or manually adjusted or a combination of both.

[46] A result of the performance evaluation stage 22 is compiled into a findings report 22 detailing the accuracy and efficacy of the MPs analysis process. The findings report 22 may include discrepancies, potential sources of error, and recommendations for protocol improvements. The findings report 28 may include an executive summary including a concise summary of the key findings, including major observations and conclusions drawn from the analysis and performance evaluation. The findings report 28 may include a comparative analysis including in-depth comparison of the analysis data 20 with the reference data 18 of the MP-SRM tablet, highlighting (and quantifying) consistencies and discrepancies. The findings report 28 may include visual representations like graphs, tables, and charts to illustrate the comparison in a user-friendly manner. The findings report 28 may include presentation of statistical measures such as recovery rates, precision, accuracy, and error margins. The findings report may include an interpretation of the results including a detailed interpretation of what the data reveals about the performance of the microplastic analysis protocols and equipment. The finding report 28 may include identification and discussion of potential sources of error or variations observed. The findings report 28 may include adjustment recommendations such as protocol adjustment (suggestions for adjustments in the analytical methodologies to enhance accuracy and precision) and equipment calibration (recommendations for recalibration or adjustments in equipment settings, if needed). In some embodiments, Al-driven recommendations may be provided. When Al and machine learning tools are integrated, the findings report 28 could include automated instructions or algorithms for adjusting protocols and equipment settings based on the analysis outcome. Such machine implemented adjustment commands may include instructions for adapting separation and analysis protocols dynamically, optimizing them for future analyses.

[47] Each stage of the microplastics analysis and evaluation system 24 can be potentially automated. For sample preparation, automated dispensers and mixers ensure consistent sample quality. The MPs separation and analysis stage 16 can utilize image recognition software for automated particle identification. The performance evaluation stage 22 is particularly suited for Al implementation, where algorithms can process large datasets, comparing analysis results with reference data, and highlighting discrepancies efficiently. The entire pipeline from mixing the solution 14 and the MP-SRM tablet 10 to generating the findings report 28 may be automated by a combination of robotic equipment and control instructions defined by programming that is executed by one or more processors of a computer controller.

[48] Referring to FIG. 2, an exemplary method 200 of using the MP-SRM tablet 200 is illustrated in a flowchart. The method 200 involves a series of steps designed to assess and improve the accuracy and reliability of microplastics analysis methodologies using the MP-SRM tablet. In step 210, the testing solution 14 is prepared. In this initial step, a suitable testing solution 14 is prepared, which will be used to dissolve the MP-SRM tablet 10. The solution 14 is chosen based on its ability to mimic environmental conditions relevant to microplastic analysis and support the effervescent action of the tablet. The solution 14 could be a saturated salt solution or any other appropriate medium as described previously. The concentration and volume are carefully measured to ensure consistency in the testing process.

[49] In step 220, the MP-SRM tablet 10 is introduced to the solution 14. This is performed carefully to ensure that the tablet dissolves evenly and releases the microplastics uniformly. The effervescent nature of the tablet aids in the quick and even dispersion of microplastics in the solution 14, simulating how microplastics are distributed in natural water bodies.

[50] In step 230, microplastics analysis is performed on the sample 26 resulting from step 220. Once the tablet is dissolved, and microplastics are evenly dispersed in the solution 14, the analysis is performed. This involves separating the microplastics from the solution 14, usually through filtration or sedimentation, followed by their identification and quantification. Advanced analytical techniques like microscopy, spectroscopy, or automated imaging systems may be used to characterize the microplastics based on size, shape, color (optionally), and polymer type (optionally).

[51] In step 240, performance of microplastics analysis equipment and procedure is evaluated. This step involves comparing the results (analysis data 20) of the microplastics analysis (quantity, size distribution, shape, etc.) with the known reference data 18 associated with the MP-SRM tablet. The performance evaluation assesses the accuracy, precision, and overall effectiveness of the analysis equipment and procedures. Any discrepancies or anomalies are noted for further investigation and / or reporting.

[52] In step 250, the findings from the performance evaluation step 240 are compiled and reported. This report includes a detailed comparison of the analysis data 20 with the reference data 18, and optionally provides insights into the efficacy of the analysis methodology and / or recommendations for improvements. The report serves as a document for quality control, method validation, and as a guide for further refinement of microplastics analysis techniques. The findings report 28 may be provided to the user digitally through a dedicated application, via an online portal, by email or on a local computer screen or in any other way. In other embodiments, the findings report 28 is prepared manually.

[53] Referring to FIG. 3, a method 300 of producing the MP-SRM tablet 10 is represented by a flowchart. The method 300 encompasses the collection of environmental samples, extraction and characterization of microplastics, creation of the tablet, and its subsequent packaging and association with reference data.

[54] In step 310, an environmental sample is collected. The first step involves collecting environmental samples from which microplastics will be extracted. These samples can be sourced from various environments such as wastewater, ocean water, river sediments, or sludge. The collection methods are designed to minimize contamination and ensure a representative sample of the environment. This might involve using pre-cleaned containers, specific sampling techniques, and careful handling and transportation of samples. Step 310 may include removing large debris and particulate matter through sieving or settling. Step 310 may include digestion by which organic matter in the samples is digested to isolate microplastics. This may be carried out using oxidation agents like 30% hydrogen peroxide (H2O2) or potassium hydroxide (KOH). The digestion process breaks down organic material without affecting the microplastics.

[55] In step 320, microplastics are extracted from the collected environmental samples. This involves processes like filtration, sedimentation, and density separation to isolate microplastics from other materials. Once isolated, the microplastics are characterized. This includes determining their size, shape, and polymer type. Advanced techniques such as microscopy and spectroscopy are employed for accurate characterization. The data gathered in this step forms the basis of the reference data 18 for the MP-SRM tablet 10. Step 320 may perform an analysis on the extracted sample using similar techniques to those described above with respect to the MPs separation and analysis stage 16.

[56] Step 320 may thus include density separation, which utilizes the difference in density between microplastics and other components in the sample. The sample is mixed with a high-density solution (e.g., saturated salt solutions like NaCI, ZnCh and other described above). Microplastics, being less dense, float to the surface and can be separated. Step 320 may further include filtration by use of fine-mesh filters or membranes to capture microplastics from the solution. Filters with appropriate pore sizes (e.g., 0.2 to 0.45 micrometers) for removing microplastics. Step 320 may include characterization of microplastics by, for example, observing under a microscope to identify their physical attributes. The shape, and size, of each particle is documented. Common shapes include fragments, fibers, beads, and films. Polymer identification may be performed using techniques like Fourier-Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy to determine the chemical composition of the microplastics. The dimensions of each microplastic particle may be measured using software tools associated with microscopic analysis. The total number of microplastic particles within each category (size, shape, type) may be counted. The concentration of microplastics in the original sample may be calculated, which provide for reference data formulation.

[57] In step 330, the MP-SRM tablet 10 is created. The manner by which the MP-SRM tablet 10 is created has been described in the foregoing according to exemplary embodiments. A mixture is prepared comprising of binding agents (like sodium bicarbonate, citric acid, and glycocoll) and the characterized microplastics. The proportions are carefully calculated to ensure consistency and the desired effervescent property. This mixture is then compressed into tablets using tablet-making equipment. The dimensions of the tablet (e.g., 30 mm diameter, 8 mm thickness) are controlled to meet predefined specifications.

[58] In step 340, the MP-SRM tablet 10 is packaged and associated with reference data 18. This step involves packaging the MP-SRM tablet 10 in a way that protects it from contamination and degradation. The packaging material is chosen for its ability to preserve the tablet's integrity. Each tablet or batch of tablets is then associated with the corresponding reference data 18, which details the specifics of the microplastics contained within the tablet (such as number, size, shape, and polymer type). This association can be facilitated through various means such as including printed documentation with the package, using QR codes, or providing unique identification numbers that link to a digital database. The reference data 18 allows users of the MP-SRM tablet 10 to compare their analysis results with a known standard, thereby evaluating the efficacy of their microplastics analysis methods.

[59] The MP-SRM tablet 10 so manufactured can subsequently be used in the microplastics analysis evaluation system 24 of FIG. 1 and the method 200 of use of FIG. 2.

[60] In an alternative to the method 300 for manufacturing the Microplastic MP-SRM tablet 10 of FIG. 3, instead of extracting microplastics from environmental samples, standardized or laboratory-synthesized microplastic particles are used. These particles, encompass a variety of sizes, shapes, colors, and polymer types to reflect environmental samples. After thorough characterization for size, shape, and polymer composition using methods described with reference to FIG. 3 (step 230), these microplastics are mixed with a biodegradable binding agent and then compressed into tablets. Each tablet is then packaged and associated with detailed reference data that documents the characteristics of the included microplastics, ensuring consistency and accuracy for use in microplastics analysis.

[61] Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practised otherwise than as specifically described herein.

Claims

1. An environmentally degraded microplastic Standard Reference Material (MP-SRM) comprising an effervescent tablet, said tablet containing a predetermined quantity of microplastic particles recovered from environmental samples varying in one or any combination of two or more of: shapes, sizes, and polymer types.

2. The MP-SRM of claim 1, wherein the tablet is between 10mm and 100mm along a major axis, such as diameter or length, extending parallel to opposed parallel surfaces and between 5mm and 50mm in thickness between the opposed parallel surfaces.

3. The MP-SRM of claim 1 or 2, wherein the microplastic particles within the tablet range in size from 1 pm to 5000 pm.

4. The MP-SRM of claim 1,2 or 3, wherein the microplastic particles within the tablet include at least one of: primary microplastics manufactured for incorporation into products and secondary microplastics resultingfrom the breakdown of larger plastic debris.

5. The MP-SRM of any preceding claim, wherein the microplastic particles within the tablet are of various polymer types, including any combination of two or more of: polyethylene, polypropylene, polyethylene terephthalate, and polystyrene.

6. The MP-SRM of any preceding claim, wherein the environmental samples include wastewater influent and / or sludge samples and / or waste streams.

7. A method for assessing the accuracy of microplastic analysis procedures, comprising the steps of dissolving the MP-SRM of any preceding claim in a solution used for density separation, and subsequently processing the solution using microplastic analysis techniques.

8. The method of claim 7, further comprising the step of comparing the results obtained from the microplastics analysis techniques with known characteristics of the microplastic particles within the tablet to identify errors.

9. The method of claim 8, comprising quantifying the identified errors based on the comparing.

10. The method of claim 8 or 9, wherein the comparing is performed by at least one processor executing computer program instructions.

11. A method for producingthe Microplastic Standard Reference Material (MP-SRM) of claim 1, comprising the steps of segregating microplastic particles from environmental samples, analysing the segregated microplastic particles to determine characteristics of25the microplastic particles, providing reference data representing the determined characteristics and incorporating the segregated microplastic particles into an effervescent tablet using at least a binding agent.

12. The method of claim 11, wherein the reference data is provided as a digital file and / or in hardcopy.

13. A packaged MP-SRM tablet, the MP-SRM tablet being according to claim 1, wherein the package and / or the MP-SRM tablet includes reference data characterizing the microplastic particles in one or any combination of two or more of: shapes, sizes, and polymer types or wherein the reference data is associated with the package orthe tablet in the form of an identifier or a link to the reference data included in a server or other remotely accessible computer.

14. The packaged MP-SRM tablet according to claim 13 in combination with the server or the remotely accessible computer having the reference data stored on memory thereof.

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