5.1 Silver may be used to treat consumer textile products to provide enhanced antimicrobial (fungi, bacteria, viruses) properties (3, 4). At any point in a textile product's lifecycle, there may be a need to measure the amount of silver present. This standard prescribes a test method based on ICP-OES or ICP-MS analysis that manufacturers, producers, analysts, policymakers, regulators, and others may use for measurement of total silver in textiles. As described in Guide E3025, determination of total silver in a consumer textile product is one component of a tiered approach to determine if silver is present, possibly as nanomaterial(s) (one or more external dimensions in the nanoscale), prior to measuring the form and dimension of the Ag that is found. ICP-OES or ICP-MS analysis alone is not sufficient to determine whether a textile contains silver nanomaterial(s).

Note 4: 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 Guide E3025.

5.2 As described in Guide E3025, the amount of silver in a textile can decrease over time as silver metal and silver compounds can react with oxygen and other oxidation-reduction (redox) active agents present in the environment to form soluble ionic species which are released by contact with moisture (for example, from ambient humidity, washing, body sweat, rain, or other sources). Hence, if silver is measured in a textile, the result may only be indicative of that moment in the article's life cycle and great care is necessary in drawing temporal inferences from the results.

5.3 If silver is measured by ICP-OES or ICP-MS analysis, additional analyses are needed to elucidate the form of silver in the textile specimen. This step is necessary because ICP-OES or ICP-MS results are for total silver independent of chemical and physical form and textiles may be treated with silver in sizes that range from the nanoscale (for example, salt nanoparticles) to the micrometer scale (for example, particulates or fibers).

5.4 If no silver is detected by ICP-OES, the more sensitive ICP-MS should be used to determine if silver is present in a test specimen. If no silver is detected in a textile sample using appropriate (fit for purpose) analytical techniques, then testing can be terminated.

Note 5: Typical method detection limits are 0.6 µg Ag/L by ICP-OES and 0.002 µg Ag/L by ICP-MS which are comparable to limits successfully used to detect silver in a range of products, including sports textiles and wound dressings (2).

5.5 Results of ICP-OES or ICP-MS analysis may be qualitative or quantitative, depending upon the efficacy of the digestion procedure for the textile matrix. Regardless, ICP-OES or ICP-MS analysis is recommended as a first step to screen for the presence of silver in a textile and results can be used to inform subsequent more detailed analyses as part of a tiered approach to determine if a textile contains silver nanomaterial(s).