TLC Detection and Theoretical Structure Elucidation of Nitrogen Containing Compounds with Cobalt Thiocyanate

Forensic Science Laboratories of Maharashtra state, India, receives large number of poisoning cases pertaining pharmaceutical drug overdose and illicit drugs. Thin-layer chromatography (TLC) is a method of choice for chemical analysis due to large number of biological/non-biological samples received. This study reports cobalt thiocyanate reagent to be more effective in detecting nitrogen containing drugs like chloroquine, chlorphenamine, mephedrone, cocaine, ketamine in addition to pesticides like pretilachlor, thiamethoxam and tebuconazole when aided by TLC. These compounds (except for ketamine which gives purple) form blue color when reacted with cobalt thiocyanate due to the formation of tetrahedral cobalt (II) thiocyanate complex. However due to lack of experimental evidences, quantum mechanical calculations have been employed to deduce their structures. The theoretical structure elucidation methodology is based on examining crystal structures of ligands having similar structural relationship to present drug molecules and investigating reactive sites in each drug molecule via. Molecular Electrostatic Potential.