Simple and sensitive detection of 4-nitrophenol in real water samples using gold nanoparticles modified pretreated graphite pencil electrode

A novel, simple, sensitive and disposable gold nanoparticles modified pretreated graphite pencil electrode (AuNPs-PGPE) has been developed to overcome the surface fouling of carbon electrodes due to polymerization of phenols. The unmodified PGPE electrode displayed distinct electrocatalytic properties while reducing 4-nitrophenol (4-NP). The PGPE was prepared using a simple electrochemical treatment step of the bare GPE in NaOH solution, and the resulting electrode exhibited highly sensitive, selective and fast performance towards the determination of 4-NP. The influence of various voltammetric techniques as well as other related factors affecting the reduction peak current of 4-NP was investigated. The reduction current against 4-NP concentration at PGPE displayed a good linearity between 0.01 μM to 0.8 μM with R² = 0.9994. The PGPE was further modified by AuNPs to increase the working range of PGPE for sensing 4-NP. Both of the developed PGPE and AuNPs-PGPE could be employed to a vast concentration range of 4-NP varying between 0.01 and 100 μM. The modified electrodes were successfully tested at different amounts of 4-NP varying form low concentration 0.2 μM to high concentration i.e. 25 μM in water models.