You indicate that the subject merchandise consists of synthetic RNA molecules, which are nucleic acids. The artificially made RNA vary in size and usually have a molecular weight between 6 kg/mol to 1500 kg/mol or 20 nucleotides (nt) to 5,000 nt in length. You state that shipments usually consist of less than 1mg. RNA has many scientific applications, including those used for drug development and discovery or bioengineering. They can be used as a reference material for molecular assays, a probe for detecting/capturing DNA molecules, and an expression template in cellular assays. You indicate that your RNA product is strictly for non-clinical pharmaceutical or academic research purposes. Short RNAs (oligonucleotide synthesizer and long RNAs (>200nt) are usually made enzymatically by a process known as in vitro transcription. RNA can be shipped in either a liquid or a dry form. The liquid RNA is resuspended in either molecular grade deionized water or TE buffer (water + Tris-EDTA). TE buffer helps solubilize and protects the RNA from degrading. When the RNA is shipped dry, it is air dried in a vacuum. The CAS number for the RNA is 63231-63-0.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N319797