Rapid Electrochemical Sensing Of Hydrogen Sulfide And Nitrite In Food Based On Carbon Material Modified Electrodes

Electrochemical analysis method is a class of instrumental analysis method based on the relationship between electricity and chemical reactions on the qualitative and quantitative detection of substances, which has several advantages, such as good selectivity, high sensitivity, low cost, easy miniaturization and automation.. Hydrogen sulfide (H2S) and nitrite (NO2) which are harmful to human health, are commonly used as a food preservation substances. So it is necessary to develop fast and effective detecting methods for these poisonous species. This paper mainly study on rapid detection of H2S and nitrite. Here, using screen-printed electrodes (SPE) and glassy carbon electrode (GCE) as basis electrodes, electrochemical methods based on carbon materials are exploited for the rapid detection of these substances.1. Rapid electrochemical detection of hydrogen sulfide on SPEDifferential Pulse Voltammetry (DPV) was adopted as the main method to detect the hydrogen sulfide on SPE in a electron mediator containing solution. The logarithm of the concentration of hydrogen sulfide was related linearly with the anodic peak current of hydrogen sulfide. The linear range was from 3.16 to 1000μM. The linear equation was i=-0.0403C+0.1838 with a correlation coefficient R of 0.998, and the detection limit was 5.889 × 10-8 M. This method can be used to detect hydrogen sulfide in plant cell, and the method was further verified with recovery studies.2. Electrochemical detection of sulfide using alizarin/reduced graphene oxide modified GCE (Az/rGO/GCE)This work describes a new approach for rapid detection of sulfide using a GCE) modified with alizarin and rGO. The fabricate Az/rGO/GCE sensor shows a notable electrocatalytic activity to sulfide oxidation. The cyclic voltammetric studies showed that the currents of anodic peak centered at+465 mV in 0.2 M pH 7.0 phasphate buffer were related linearly to the concentrations of sulfide. The linear range was 0.002-3.28 mM with a correlation coefficient of 0.996. The detection limit was 1 μM. The proposed method was applied in sulfide determination of hydrogen sulfide pretreated fruits, and the method was further verified with recovery studies.3. Rapid detection of nitrite using hemoglobin (Hb) and gold nanoparticles-reduced graphene oxide composite (AuNPs-rGO) modified GCEThis work presents a new kind of biosensor which combined Hb with AuNPs-rGO to modify the gGCE to detect NO2. The biosensor utilizes the signal of direct electron transfer that generated by the redox reaction between hemoglobin and NO2, which result in methemoglobin and NO3 for the qualitatively and quantitatively detection of N NO2. AuNPs-rGO composite, Hb and Nation were dropped onto GCE performed in a sequence to fabricated the nitrite biosensor. The biosensor has an excellent property of selectivity and sensitivity by cyclic voltammetry (CV) method. The calibration curve (the reduce-peak current vs. concentration of nitrite) was fitted as equation:Ip= 0.0369 C (NO2)+0.2245 (R= 0.9918), the linear range was from 0.5 to 100 μM, and the detection limit was 0.1 μM. The method is simple, rapid and sensitive, which can be used for the nitrite detection in food and environmental samples.