Do you mean documentary or materials standards? For sizing, the generic international ISO (22412:2017 and earlier variants) and ASTM (E2490-09(15)) documentary norms are followed. These are general and not specific to the food industry. Concentration is a big discussion issue at present and there are projects in the US and the EU involved with providing material standards based on the European nano definitnion (number based). Measurements of concentration are usally ICP based and SP-ICP-MS has found considerable application as a technique.

See also the attached from ANSI-NSP.

Thanks Prof. Alan F Rawle

Thanks Prof. Magdy Zahran