Certain stable isotopes—particularly deuterium and isotopically enriched materials with nuclear or dual-use applications—may be controlled under the EAR administered by the Commerce Department's Bureau of Industry and Security. Importers should confirm the ECCN classification of the specific isotope and its intended end use. While import controls are less common than export controls for these materials, re-export restrictions can affect purchasing decisions for US distributors.

Isotopic enrichment level (expressed as atom percent of the target isotope) and chemical purity are the two key specifications. For pharmaceutical tracer applications, isotopic purity typically must exceed 99 atom percent, and chemical impurities must meet USP or ICH guidelines. For NMR solvents such as deuterated chloroform or DMSO-d6, deuterium content and residual proton signal are the critical quality parameters. Mismatched specifications between buyer and seller are a common source of commercial disputes in this niche market.