Synthesis and characterization of cobalt nitroprusside nano particles: Application to sulfite sensing in food and water samples

A new protocol toward the synthesis of cobalt nitroprusside (CoNP) coordination nanoparticles has been described based on drop-by-drop (DbD) method without using any additives. It was also prepared by sonication as well as bulk mixing methods for comparison purpose. The prepared complex was characterized by Infrared spectroscopy (FTIR), XRD and cyclicvoltammetry (CV) techniques. The CoNP complexes prepared by different synthetic approaches were used as modifier molecules to fabricate carbon paste electrodes (CPE's) toward electrochemical oxidation of sulfite. The experimental results revealed that the cobalt nitroprusside nanoparticles (n-CoNP) prepared by drop-by-drop method showed a considerable enhancement in the electrocatalytic activity when compared to its counterparts prepared by other approaches. Electrochemical behavior of the n-CoNP CPE was studied and used as an electrochemical sensor for the quantification of sulfite at trace level. It showed a linear response over the concentration range 1–5.9 × 10−5 M and 2–8 × 10−3 M of sulfite. The limit of detection and limit of quantification were found to be 0.4 × 10−5 M and 2.29 × 10−5 M respectively. The interference of various organic acids and inorganic ions commonly present in different food and water sample matrices were studied. The n-CoNP modified electrode was used for the quantification of sulfite in different food samples and the results were in good agreement with those obtained by the standard iodometric protocol.

► n-CoNP was synthesized by drop-by-drop method under aqueous condition.
► Simple synthetic protocol and highly reproducible.
► No additives used during synthesis.
► n-CoNP showed significant enhancement in the electrocatalytic activity.
► It has been applied for sulfite quantification in food and water samples.