Electroanalysis Determination of Nitrite Ions Using Nano Zeolite Modified Carbon Paste Electrode

The determination of nitrite concentration, especially for drinking water quality, wastewater treatment, for the food industry , dyes, bleaches, fertilizers as well as for medicinal purposes and for the control of remediation procedures, is of rapidly increasing interest[1-2]. Nitrite ions are critical precursors in the formation of nitrosamines, many of which have been shown to be carcinogens and harmful on our environment [3]. Nitrite ions are used as food preservatives against food poisoning microorganisms such as clostridium botulinum[4]. The nitrite salts are known to occur in high quantity in soil and ground waters. Then, determination of nitrite has received substantial attention. several methods have been developed to determination nitrite, which are laborious to perform or require chemical reagents , the electrochemical approaches are favorable due to the rapid response, low costs and simple operation in compare of other methods [5]. In this research nano zeolite-modified electrodes have been developed for the determination of nitrite ions. Zeolite-supported electrocatalysts can be subjected to improve the performance of the electrocatalytic responses with reduced overpotentials and increased electroanalysis signals allowing low detection limits and high sensitivities. The used nano ZSM-5 zeolite was synthesized as literature [6]. Graphite powder and ferrous chloride ,phosphoric acid, and sodium nitrite used in this work were also purchased from Merck. Electrochemical experiments were carried out using a potentiostat/galvanostat (Auto Lab PG 302 N). An Ag|AgCl|KCl (3M) electrode as reference electrode, a platinum wire as the auxiliary electrode and carbon paste electrode modified with nano zeolite as the working electrode were used. Appropariated ammount of synthesized nano zeolite was lightly ground and immersed to 10 ml 1 M FeCl2 414 solution for 3 h. Then the solid was dried. The 30% (W/W) Fe2+-zeolite to graphite powder paste was made by mixing the given quantity of Fe2+-zeolite and graphite powder in diethyl ether and the solvent was evaporated by stirring a mixture. Then paraffin was blended by hand mixing and the resulting paste was inserted in the bottom of a glass tube. The electrical connection was implemented by a copper wire fitted into the opposite opening of the glass tube. For the comparission the unmodified carbon paste was prepared. Obtained results show that proposed modified carbon paste electrode can used for couantitative determination of nitrite inos with detection limit 1.45*10-6 M and the catalytic rate constant for this process was calculated as 2.75*103 M-1 s-1 (Fig 1). Figure 1, Cyclic voltammograms of (a) CPE in the absence and (b) Zeolite/CPE (c) Fe/Zeolite/CPE in the presence of nitrite in phosphate buffer The scan rate was 10 mV s-1.