Novel polymer-supported quenching reagents of Formula (I): P-L-Q, wherein P is a polymer of low chemical reactivity which is soluble or insoluble; Q is one or more quenching reagents, or an acid or base addition salts thereof, that are capable of selective covalent reaction with unwanted byproducts, or excess reagents; and L is one or more chemically robust linkers that join P and Q; are described, as well as methods for their preparation and methods for their use in the rapid purification of synthetic intermediates and products in organic synthesis, combinatorial chemistry and automated organic synthesis.