Quantum chemical studies and electrochemical investigations of pyrogallol red modified carbon paste electrode fabrication for sensor application

•Quantum and electrochemical studies of pyrogallol red modified carbon paste electrode towards sensing application.•Density functional theory concepts were used to identify redox reactive sites on the pyrogallol red.•Proposed sensor was applied to paracetamol determination in pharmaceutical sample.•Interference free electroanalysis at electrode makes it as a promising sensing platform.