Under optimized conditions, the calibration plot was constructed
using chemically modified amino-calixarene graphite as an electrode
interface towards mercury ions in the range 10–100 nM (Fig. 2(a) and
Fig. 2(b)). The peak current has increased during successive additions
of mercury in to an electrochemical cell containing phosphate buffer of
pH 8. The detection limit (3σ) was found to be 2.49 nM. In the present
investigation, graphite has been used as substrate material and aminocalixarene
as a modifier molecule. The amino-calixarene modified
graphitic material has shown a good analytical response towards the
mercury ion due to the presence of functional groups such as amide
bond(CONH) which enhances the electron transfer rate. The presence
of these groups on the surface of graphite provide enhances the
analytical signal intensity due to the coordination between functional
motifs on the substrate surface and metal ions present in electrolyte
solution at the interface which is mainly responsible in the enhancement
of the detection limit in the present study.