Common Interferences in Biofluid Analyses

Commonly used drugs, dietary constituents and food additives may be electroactive and consequently are potential sources of interference when biological samples are analysed. Quinine may originate from tonic water, for example, caffeine from coffee and cafifeinated soft drinks and some proprietary stimulants, nicotine and cotinine from tobacco smoke, chloroquine and related compounds from malaria prophylaxis, and pholcodine and other opiate analogues from cold cures. Many such compounds and their metabolites will show an EC response at carbon electrodes under appropriate conditions and can be sources of confusion if unrecognised. 

Paracetamol, for example, is a very widely used drug and is easily oxidised. The detection of paracetamol after therapeutic administration at concentrations 

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