SELECTRA-SIL® Reagents are packaged by weight but are liquid in form. UCT’s derivatizing reagents are synthesized and purified by UCT to exacting standards of purity and consistency. The reagents are packaged under nitrogen, sealed with a PTFE stopper and crimp topped to maintain an inert atmosphere. If stability of the reagents is a concern, UCT offers reagents packaged in sealed glass ampules, packaged under an inert atmosphere.