The development of a sample preparation protocol is challenging for a number of reasons. ENMs have large surface-to-volume ratios and, on exposure to various media, may undergo transformations such as agglomeration and adsorption of natural organic matter during sample preparation. Typically, each type of measurement requires that a sample be in a specific physical form; thus, a number of different sample preparation procedures are required for measurements of ENMs, composites, or NEPs by multiple methods. Finally, reproducibility of sample preparation procedures can only be ascertained via measurements of specific ENM properties.
Following is a list of sample preparation protocols. The first five address dispersion of nanoparticles for subsequent environmental or biological testing and were developed in collaboration with researchers at the Center for the Environmental Implications of NanoTechnology (CEINT) at Duke University.
NIST SP 1200-24: Sucrose density gradient centrifugation for efficient separation of engineered nanoparticles from a model organism, Caenorhabditis elegans