<prompt> Which is not an aryl phosphate -ParathionTIK-20MalathionParaoxon  <response>: Organophosphate poisoning is the most common poisoning in India followed by aluminium phosphide. Organophosphorus compounds are classified as 1. Alkyl compounds -- such as tetraethyl pyrophosphate TEPP, hexa ethyl tetraphosphate HETP, octa methyl pyrophosphate OMPA, malathion etc. 2. Aryl compounds -- such as parathion, chlorothion, diazinon Tik-20, paraoxon etc. REF;THE SYNOPSIS OF FORENSIC MEDICINE:KS NARAYANA REDDY;28th EDITION;PAGE NO 291 