Synthesis of albumin capped gold nanoparticles and their direct attachment on glassy carbon electrode for the determination of nitrite ion

Development of a facile method for the detection of nitrite ion is very important due to its huge impact on environment. In the present study, water soluble bovine serum albumin capped gold nanoparticles (BSA-AuNPs) were directly attached on glassy carbon (GC) electrode for the sensitive determination of nitrite ion. The BSAAuNPs were synthesized and HR-TEM images showed that the average size was similar to 5 nm. The BSA-AuNPs were then directly attached on GC electrode without any external linker and confirmed by SEM, EDS, XPS, DRS and CV. The appearance of peak at 286 eV (C-N) in XPS confirmed that BSA-AuNPs were attached on GC substrate through Michaeli's nucleophilic addition. The GC/BSA-AuNPs electrode showed an excellent catalytic activity towards nitrite by not only shifting its oxidation potential towards less positive potential by 150 mV but also enhanced its oxidation current by 3-fold compared to bare GC electrode. The amperometric current was increased linearly while increasing nitrite concentration from 10 x 10(-9) to 1 x 10(-6) M (R-2 = 0.9917) and the limit of detection (LOD) by amperometry was found to be 2 x 10(-9) M (S/N = 3). The real-time application of the present electro-catalyst was evidenced by determining nitrite in water samples.