Nitrite detection

Diamond electrodes are useful for the detection of other electroactive anions, such as nitrite [30]. Nitrite is used in the manufacture of diazo dyes and other organic compounds, dyeing and printing of textile fabrics, and in meat curing and preserving processes. In recent years there has been increasing public concern about levels of the compound in processed foods. Exhaustive electrolysis revealed that the reaction proceeds as (30) 

The linear dynamic range is 5 orders of magnitude. The theoretical detection limit (S/N = 3), based upon extrapolation of the linear-response curve, is 7 nM (16 pg or 0.3 ppb). Experimentally, an ion chromatogram for 50 pL of 0.01 pM nitrate had a peak easily detected with a S/N of 5. The response variability ranged from 2% at high concentrations to 8% at the lowest injected concentration (10 nM). 

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Reshetelov AN, Iliasov PV, Knackmus HJ, Boronin AM (2000) The nitrite oxidizing activity of Nitrobacter strains as a base of microbial biosensor for nitrite detection. Anal Lett 33 29-41... 

Fig. 7.14 Nitrite detection by IC electrolysing water in a discontinuous cell with rotating BDD anode (300 rpm, Ir02 cathode, 100 mL, initial concentration 47 ppm nitrate + 9 ppm chloride as sodium salts, 20° C)...

The required working potential ( =-700mV and 200 mV for nitrate and nitrite detection, respectively), which requires sample purging, is not the only problem confronting these sensors. When developed with commercially... 

Figure 33. (A) CV response of GC electrode modified with CoOx Nanoparticles in pH 12 solutions at v = 20 mVs 1 (B) SEM image of the electrodeposited CoOx on GC electrode. Reprinted from Analytica Chimica Acta, 594, A. Salimi, R. Hallaj, H. Mamkhezri, S. Soltanian, Nanomolar detection of hydrogen peroxide on glassy carbon electrode modified with electrodeposited cobalt oxide nanoparticles,26,Copyrights(2007) and J. Electroanalytical Chemistry, 619-620, A. Salimi, R.Hallaj, H. MamKhezri, S.M.T. Hosaini, Electrochemical properties and electrocatalytic activity of FAD immobilized onto cobalt oxide nanoparticles Application to nitrite detection,33, Copyrights (2008) with permission from Elsevier.

The concentration of azo compound obtained can be determined either color-imetrically, using a comparator, or spectrophotometrically. The nitrite-detection limit of this method is 0.02 mg/L of nitrite, specified as N, which is equivalent to 0.02 ppm or 20 ppb N in fresh waters [24]. 

V. Biagiotti, F. Valentini, E. Tamburri, M.L. Terranova, D. Moscone and G. Palleschi, Synthesis and characterization of polymeric films and nanotubule nets used to assemble selective sensors for nitrite detection in drinking water. Sens. Actuat. B, 122, 236-242 (2007). 

Amperometric nitrite detection at 0 V was conducted with a PANl-MWCNT-Au electrode [52]. The electrode showed a large electrocatalytic activity towards reduction of nitrite compared to the bare Au, MWCNT-Au and PANl-Au electrodes on which the nitrite reduction response was almost undetectable. Na", K", Ca ", Mg2", AP", CP, NO3, CIO3, H2PO , HPO , C0 , S0 (50-fold excess to nitrite) and Zn ", Cd ", Ba ", and Br (10-fold excess), UA and AP did not interfere with the nitrite detection, whereas Fe ", Cu ", P, BrOj, IO3, and AA were interfering. 

The determination of nitrite in egg highlights the beneficial aspects of sonoelec-trochemical analysis in difficult matrices. Moreover, the advantages of the technique include significant simplification over the liquid chromatographic procedure currently employed for nitrite detection [69], which involves hot water extraction, protein precipitation and solid-phase extraction / purification. 

Winnischofer, H., S.D. Lima, K. Araki, and H.E. Toma (2003). Electrocatalytic activity of a new nanoslmctured polymeric tetraruthenated porphyrin film for nitrite detection. Arud. Chim. Acta 480,97—107. 

Figure 15 Reaction-based aggregation protocol for nitrite detection." ...

The cell concentration was determined by optical density (OD) measurement at 600 nm and compared with an OD versus dry weight calibration curve. Nitrate and nitrite concentrations were measured using a segmented flow analyzer (Skalar analytic ). Nitrite detection was based on the colorimetric reaction with N-(l-naphthyl)-ethylenediamine nitrate was detected as nitrite by the same method after reduction by hydrazine. DOC was also measured using the segmented flow analyzer. Carbon compounds were detected as... 

Winnischofer H, Lima SD, Araki K, Toma HE (2003) Electrocatal5rtic activity of a new nanostmctured polymeric tetraruthenated porphyrin film for nitrite detection. Anal Chim Acta 480(1) 97-107... 

Liu S, Tian J, Wang L, Luo Y, Sun X (2011) Production of stable aqueous dispersion of poly (3,4-ethylenedioxythiophene) nanorods using graphene oxide as a stabilizing agent and their application for nitrite detection. Analyst 136 4898... 

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