Chemical compounds known as pan-assay interference chemicals (PAINS) frequently produce results that are false-positive (false hits) in high-throughput screening assays. Instead of directly impacting intended targets, they frequently react in a non-specific manner with many biological targets. Since the PAINS compounds are bad hits, they are frequently removed from compound libraries. Compounds that have the potential to be reactive or promiscuous are also found using the alert NMR rule. A reliable indication of potential phase I and phase II metabolic reactions of substances can be found in the reactivity warnings from alarm NMR. The Bristol-Myers Squibb (BMS) rule is used to screen out harmful reactive substances and chemicals that have the potential to be toxic. Chelators such as crown-ether-like compounds are especially undesirable in drug discovery inputs and are rejected because of their potential to act as ionophores in addition to their poor druggability. However these filters, it cannot distinguish between bad or innocent suspects this includes covalent inhibitors.