5.1 A nano-object is an individual, well-defined, and separable piece of a nanomaterial; in practice, nanomaterials used in research, products, testing, and other uses are almost always collections of nano-objects. Individual nano-objects and collections of nano-objects are the two major types of nanomaterials in use. The description of a collection of nano-objects is covered in this guide. The description of an individual nano-object is covered in Guide E3144. Nano-objects, individually or as a collection, are often embedded in other materials for commercial, research, and other uses. These embedded nanomaterials can be described using the information categories and descriptors included in these guides.

5.2 Nanomaterials are of growing importance in research and commerce, and data on their physical and chemical characteristics are critical to predict performance, to transact commercial activities, to assess their potential for harm to human and animal health and the environment in general, and to support regulations that affect their use. A collection of nano-objects is the predominant type of nanomaterial tested and used in commerce.

5.3 The four types of data and information used to describe a collection of nano-objects are: physical and chemical characteristics; production; specifications; and general identifiers (names and classifications), as shown in Fig. 1.

FIG. 1 Data and Information Types Necessary to Describe a Collection of Nano-Objects

Used with permission of CODATA from "Uniform Description System for Materials on the Nanoscale," Version 2.0, http://doi.org/10.5281/zenodo.56720.

5.4 This guide deals solely with data and information to describe the physical and chemical characterization of a collection of individual nano-objects.

Note 2: Other guides and documents (see Section 2, Referenced Documents) deal with the data and information for production, specifications, and general identifiers (names and classifications).

Note 3: Specifications are formal or informal documents that provide guidance on specifying the composition, structure, or any other aspect of a nano-object or a collection of nano-objects.

5.5 In a practical sense, the amount of data and information reported to describe the physical and chemical characteristics of a collection of nano-objects differs widely depending on who is reporting and the reason they are reporting. Researchers examining specific aspects of a collection of nano-objects can choose to report a limited subset of characteristics. For example, a test report on the potential toxicity of a collection of nano-objects can choose to report numerous characteristics. This guide supports both limited and complete reporting of characteristics enumerated herein.

5.6 The science of characterizing collections of nano-objects is still evolving. Some information categories will require additional descriptors as new knowledge is developed. Some descriptors can become obsolete. Users should consult the latest guide for the most complete recommendations.

5.7 The technology for collecting, storing, analyzing, and disseminating scientific and technical data continues to evolve, and tools such as ontologies, database schemas, data repository reporting requirements, and data recoding formats are evolving similarly. This guide provides a clear, English language definition of information categories and descriptors used to describe a collection of nano-objects that can be used in these and other similar tools.

5.8 A collection of nano-objects has properties and functionalities that are measured under specific measurement conditions. The description of a collection of nano-objects requires data and information on its properties as well as on the conditions under which those properties were measured, as shown in Fig. 2.

FIG. 2 Data and Information Components Necessary to Describe a Nanomaterial and Its Properties

Used with permission of CODATA from "Uniform Description System for Materials on the Nanoscale," Version 2.0, http://doi.org/10.5281/zenodo.56720.

5.9 The characteristics of a collection of nano-objects defined in this guide address the important physical and chemical properties of that collection. Because the techniques and instruments used to measure these properties can greatly influence the property value, when available, the measurement result being used should include as much information as possible about the measurement conditions.

5.10 This guide is designed for use whenever the data and information on the physical and chemical characteristics of a collection of nano-objects are reported.