Prior to modification, the surface of glassy carbon was manually
polished to a mirror like finish with a paste of alumina powder
(gradeI) and ZnO on micro-cloth pad and was rinsed with
double distilled water.The electropolyamerization of melamine was
carried out on the polished surface of GCE in a solution of 10 mM
melamine (prepared in 0.1 M H2SO4). The cyclic voltammograms
were recorded by scanning the potential between 0 V and þ1.6V
at a scanrate of 100 mVs1 for 20 scans [32]. The film obtained
was rinsed with double distilled water and allowed to dry at room
temperature.To optimize the volume of AuNP , 2–15 mL was casted
on the modified GC surface and voltammograms were recorded in
10 mM of DOM.The maximum peak current was observed when
10 mL of AuNP solution was drop casted onto the poly-melamine
modified GC surface; therefore,it was selected as the optimum
volume and was used throughout the experiment as modification
protocol.The final sensing surface was obtained just after rinsing
with double distilled water, which was characterized with the help
of FE-SEM and used for further electrochemical studies.