5.1 NTA is one of the very few techniques that are able to deal with the measurement of particle size distribution in the nano-size region. This guide describes the NTA technique for direct visualization and measurement of Brownian motion, generally applicable in the particle size range from several nanometers until the onset of sedimentation in the sample. The NTA technique is usually applied to dilute suspensions of solid material in a liquid carrier. It is a first principles method (that is, calibration in the standard understanding of this word, is not involved). The measurement is hydrodynamically based and therefore provides size information in the suspending medium (typically water). Thus the hydrodynamic diameter will almost certainly differ from size diameters determined by other techniques and users of the NTA technique need to be aware of the distinction of the various descriptors of particle diameter before making comparisons between techniques (see 8.7). Notwithstanding the preceding sentence, the technique is routinely applied in industry and academia as both a research and development tool and as a QC method for the characterization of submicron systems.1.1 This guide deals with the measurement of particle size distribution of suspended particles, from ~10 nm to the onset of sedimentation, sample dependent, using the nanoparticle tracking analysis (NTA) technique. It does not provide a complete measurement methodology for any specific nanomaterial, but provides a general overview and guide as to the methodology that should be followed for good practice, along with potential pitfalls.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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This guide specifies the format for representing and sharing information about nanomaterials, small molecules and biological specimens along with their assay characterization data using spreadsheet or TAB-delimited files. It is intended to facilitate the meaningful submission and exchange of nanomaterial descriptions and characterization data (metadata and summary data) along with the other files (raw/derived data files, image files, protocol documents, etc.) among individual researchers and to or from nanotechnology resources. It also provides researchers with guidelines for representing nanomaterials and characterizations to achieve cross-material comparison.1.1 This guide (ISA-TAB-Nano) specifies the format for representing and sharing information about nanomaterials, small molecules and biological specimens along with their assay characterization data (including metadata, and summary data) using spreadsheet or TAB-delimited files.1.2 The Appendices Sections contain a detailed listing of ISA-TAB-Nano fields (Appendix X1), a practical example (Appendix X2), a discussion of optional files (Appendix X3), and summary of background (Appendix X4).1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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5.1 The information and recommendations in this guide are relevant for imaging and identifying ENMs in cells and other biological (for example, fixed tissues, whole plants) and nonbiological (for example, drug formulations, filter media, soil, and wastewater) matrices after appropriate sample preparation procedures have been performed (3-5). DFM/HSI is a recently developed analytical tool; however, the relative simplicity of sample preparation combined with the potential to acquire high-contrast ENM images and high-content ENM spectral responses facilitates the increasing use of the tool for diverse applications in drug delivery, toxicology, environmental science, biology, and medicine.5.2 Verification of the uptake and spatial distribution of ENMs in cells, for example, is necessary for evaluating and understanding the biological effects of ENMs on living systems. Similarly, the closeness of the spatial distribution of ENMs in complex drug formulations can be an important criterion in establishing physicochemical similarity between formulations (6). Complex products are described in the most recent version of the Generic Drug User Fee Act (GDUFA) reauthorization commitment letter: (7). This guide covers the criteria and general considerations for performing DFM/HSI analyses on samples of biological and nonbiological origins containing ENMs (for example, metal and metal oxide nanoparticles, or carbon nanotubes, or both). This guide does not cover or address provisions for imaging or identifying, or both, non-engineered (natural) nanoparticles/nanomaterials in cells or other matrices, nor does this guide describe or discuss the application of DFM/HSI for determining the dimensions of ENMs.1.1 This guide has been prepared to familiarize laboratory scientists with the background information and technical content necessary to image and identify engineered nanomaterials (ENMs) in cells via darkfield microscopy/hyperspectral imaging (DFM/HSI) methodology.1.2 DFM/HSI is a hyphenated bioanalytical technique/tool that combines optical microscopy with high-resolution spectral imaging to both spatially localize the distribution of and identify ENMs within a suitably prepared test sample.1.2.1 In the context of mammalian cells, ENMs will have distinctive light-scattering properties in comparison to subcellular organelles and cell structural features, which can allow one to discriminate between the spectral profiles of ENMs and cellular components.1.2.2 The light-scattering properties of ENMs in other test samples, such as fixed tissues, plants, complex drug product formulations, filter media, and so forth, will also be different from the native matrix component scattering signals inherent to these other types of samples, thus allowing for ENM visualization and identification.1.3 This guide is applicable to the use of DFM/HSI for identifying ENMs in the matrices mentioned.1.4 This guide describes and discusses basic practices for setting up and using DFM/HSI instrumentation, sample imaging techniques, considerations for optics, image analysis, and the use of reference spectral libraries (RSLs). DFM/HSI is routinely used in industry, academia, and government as a research and development and quality control tool in diverse areas of nanotechnology.1.5 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 Natural and manufactured textiles fibers can be treated with chemicals to provide enhanced antimicrobial (fungi, bacteria, viruses) properties. In some cases, silver nanomaterials may be used to treat textile fibers (1).6 Silver nanomaterials are used to treat a wide array of consumer textile products, including, but not limited to, various clothing; primary garments (shirts, pants), outer wear (gloves, jackets), inner wear (socks and underwear), children’s clothing (sleepwear); children’s plush toys; bath towels and bedding (sheets, pillows); and medical devices (for example, wound dressings and face masks) (2).4.2 There are many different chemical and physical forms of silver that are used to treat textiles and an overview of this topic is provided in Appendix X1.4.3 Several applicable techniques for detection and characterization of silver are listed and described in Appendix X2 so that users of this guide may understand the suitability of a particular technique for their specific textile and silver measurement need.4.4 There are many different reasons to assay for silver nanomaterials in a textile at any point in a product’s life cycle. For example, a producer may want to verify that a textile meets their internal quality control specifications or a regulator may want to understand the properties of silver nanomaterials used to make a consumer textile product under their jurisdiction or what quantity of silver nanomaterial is potentially available for release from the treated textile during the washing process or during product use. Regardless of the specific reason, a structured approach to detect and characterize silver nanomaterials present in a textile will facilitate measurements and data comparison. Detection and characterterization of silver in textiles is one component of an overall risk assessment.4.5 The approach presented in this guide (see Fig. 1) consists of three sequential tiers: obtain a textile sample (Section 7), detection of a silver nanomaterial (Section 8), and characterization of a silver nanomaterial (Section 9). If no forms of silver are detected in a textile sample using appropriate (fit for purpose) analytical techniques then testing can be terminated. If silver is detected, but present in a non-nanoscale form, the textile is a chemical or bulk silver-containing material. Silver ions may be released from silver-containing materials, and under reducing conditions these can transform into nanoscale silver-containing particles. If nanoscale silver is detected, one concludes that the textile contains a silver nanomaterial. Subsequent measurements can characterize the chemical and physical properties of the silver nanomaterial.FIG. 1 Tiered Approach for Determining if a Textile Contains a Silver Nanomaterial (*It might not be possible to know how the nanomaterial formed in the textile. It may have been engineered or intentionally applied or transformed from another silver source.)4.6 Numerous techniques are available to detect and characterize silver nanomaterials in textiles. The breadth of options can cause confusion for those interested in developing an analytical strategy and selecting appropriate techniques. Some techniques apply only to certain chemical forms of silver and all have limited ranges of applicability with respect to a measurand. No single technique is suitable to both detect and fully characterize silver nanomaterials in textiles. This guide describes and defines a tiered approach using commercially available measurement techniques so that manufacturers, producers, analysts, policymakers, regulators, and others may make informed and appropriate choices in assaying silver nanomaterials in textiles within a standardized framework. The user is cautioned that this guide does not purport to address all conceivable textile analysis scenarios and may not be appropriate for all situations. In all instances, professional judgment is necessary.4.7 This guide provides a tiered approach to determine an efficacious and efficient procedure for detecting and characterizing silver in textiles and determine whether any silver nanomaterial is present. This tiered approach may also be used to determine whether a reported measurand for silver nanomaterials in a textile was obtained in an appropriate and meaningful way.4.8 Material property measurement depends on the method. Caution is required when comparing data for the same measurand from techniques that operate on different physical or chemical principles or with different measurement ranges.4.9 The amount of silver in a textile might decrease over time. Silver metal and silver compounds can react with oxygen and other oxidation-reduction (redox) active agents present in the environment to form soluble silver species. These soluble silver species can be released by contact with moisture (for example, from ambient humidity, washing, body sweat, rain, or other sources). As described in Appendix X1, release of soluble silver species may occur at varying rates. Release rates depend on many characteristics, including chemical nature, surface area, crystallinity, and shape, where the silver is applied to the textile (on the fiber surface, in the volume of the fiber, and so forth), and in what form the silver is applied to the textile (discrete particles, with carriers, and so forth). The condition and age of textile test samples must be considered when drawing temporal inferences from the results, as only a moment in time of the textile life cycle will be captured in the results.4.10 Textile acquisition, storage, handling, and preparation can also affect silver content.1.1 This guide covers the use of a tiered approach for detection and characterization of silver nanomaterials in consumer textile products, which can include some medical devices (for example, wound dressings or face masks), made of any combination of natural or manufactured fibers.1.2 This guide covers, but is not limited to, fabrics and parts (for example, thread, batting) used during the manufacture of textiles and production of consumer textile products that may contain silver-based nanomaterials. It does not apply to analysis of silver nanomaterials in non-consumer textile product matrices nor does it cover thin film silver coatings with only one dimension in the nanoscale.1.3 This guide is intended to serve as a resource for manufacturers, producers, analysts, policymakers, regulators, and others with an interest in textiles.1.4 This guide is presented in the specific context of measurement of silver nanomaterials; however, the structured approach described herein is applicable to other nanomaterials in consumer textile products, including some medical devices.1.5 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 PCS is one of the very few techniques that are able to deal with the measurement of particle size distribution in the nano-size region. This guide highlights this light scattering technique, generally applicable in the particle size range from the sub-nm region until the onset of sedimentation in the sample. The PCS technique is usually applied to slurries or suspensions of solid material in a liquid carrier. It is a first principles method (that is, calibration in the standard understanding of this word, is not involved). The measurement is hydrodynamically based and therefore provides size information in the suspending medium (typically water). Thus the hydrodynamic diameter will almost certainly differ from other size diameters isolated by other techniques and users of the PCS technique need to be aware of the distinction of the various descriptors of particle diameter before making comparisons between techniques. Notwithstanding the preceding sentence, the technique is widely applied in industry and academia as both a research and development tool and as a QC method for the characterization of submicron systems.1.1 This guide deals with the measurement of particle size distribution of suspended particles, which are solely or predominantly sub-100 nm, using the photon correlation (PCS) technique. It does not provide a complete measurement methodology for any specific nanomaterial, but provides a general overview and guide as to the methodology that should be followed for good practice, along with potential pitfalls.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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