The product in question is a cell conditioning solution (CC1). You state that CC1 is used as a pre-treatment step in the processing of tissue samples for immunohistochemistry reactions carried out on the Ventana BenchMark® and BenchMark XT automated slide stainers. CC1 is said to consist of over 99.5% water with the balance being: 2-Amino-2-(hydroxymethyl)propane-1,3-diol (Tris), Disodium dihydrogen ethylenediaminetetraacetate (EDTA2Na), 2-methyl-2H-isothiazol-3-one, Silicon dioxide, Boric acid, and Polyoxyethylene (20) sorbitan monolaurate (Tween 20).
[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/N320439