Fabrication of a New Electrochemical Sensor Based on Carbon Paste Electrode Modified by Silica gel/ MWCNTs for the Voltammetric Determination of Salicylic Acid in Tomato

Abstract

Walled Carbon Nano-tubes a fabrication and application of a novel sensor of carbon paste electrode modified by silica gel/MWCNTs for the determination of salicylic acid (SA) by different voltammetric techniques such as Linear Sweep, Cyclic and Square Wave Voltammetry. The electrochemical behavior of SA has been investigated and the optimum experimental conditions such as the effect of supporting electrolyte, pH and scan rate on the anodic peak of SA was determined. Square Wave Voltammetry (SWV) was employed to determine SA, where the important parameters such as frequency were achieved. Moreover, the results showed that modified electrode exhibited excellent electrocatalytic activity towards the oxidation of SA. The results showed irreversible process with one oxidation peak of SA at the surface of modified electrode and the overpotential of SA decreased significantly compared with that at the bare carbon paste electrode (CPE). This electrochemical sensor shows an excellent performance for detecting SA with a detection limit and limit of quantification were 0.9 × 10 -9 M and 2.99 × 10 -9 M respectively. In addition, the peak currents increased linearly in the concentration range of 3.0-70 nM. The results showed also, the fabricated sensor was successfully applied to the detection of SA in tomato with good recovery ranging from 96.60 to 103%, Moreover, the proposed electrode revealed good reproducibility and stability, with standard deviation (S.D.) 2.3% for eight successive measurements of SA.

A Novel Electrochemical Sensor for Detection of Nicotine in Tobacco Products Based on Graphene Oxide Nanosheets Conjugated with (1,2-Naphthoquinone-4-Sulphonic Acid) Modified Glassy Carbon Electrode

“…The slope of the above relation (α = 0.54) is close to the theoretical value calculated, 0.5, as expected for a diffusion-controlled process [ 56 , 57 , 58 ].…”

“…Moreover, Ep and Log scan rate was determined to inform the number of electron that contributed in the oxidation process of NIC on the surface ofGO/Nq/GCE as seen in Figure 10a,b. For more support, a linear relationship with a slope of 0.54 was obtained when plotting the log peak current versus log scan rate (inset Figure 9) and can be expressed by: log I p = 0.54 log υ + 0.681 (R 2 = 0.996) (4) The slope of the above relation (α = 0.54) is close to the theoretical value calculated, 0.5, as expected for a diffusion-controlled process [56][57][58].…”

“…I p (µA) = 6.117υ For more support, a linear relationship with a slope of 0.54 was obtained when plotting the log peak current versus log scan rate (inset Figure 9) and can be expressed by: log Ip = 0.54 log ʋ + 0.681 (R 2 = 0.996) (4) The slope of the above relation (α = 0.54) is close to the theoretical value calculated, 0.5, as expected for a diffusion-controlled process [56][57][58].…”

A Novel Electrochemical Sensor Based on Modified Carbon Paste Electrode with ZnO Nanorods for the Voltammetric Determination of Indole‐3‐acetic Acid in Plant Seed Extracts

“…The results indicate that increasing scan rates cause an increase and a positive slight shift in the oxidation peak current of IAA [37,38] as shown in Figure 4, however, increasing scan rate higher than 200 mV/s leads to distortion on the peak shape especially at high concentrations of IAA. Figure 4, represents the relation between peak currents and the square root of the applied scan rates which follows the relationship; Ip (mA) = 3.87 + 0.76 n 0:5 (mV/s) 0:5 (r 2 = 0.998); indicating that the oxidation process of IAA was diffusioncontrolled [39], and to confirm that, the relation between log Ip and the logarithm of scan rate was plotted, resulting in a straight line following the equation; log(Ip) = 1.3 + 0.62 log(n) (r 2 = 0.996); with a slope of 0.62 which is very close to the theoretical value of 0.5, which is supposed for a diffusion-controlled process [40]. The total number of participate electrons was calculated from Laviron eq; DE=D(n) = 0.059/na; by plotting the Ep versus log(ν), which followed the equation; Ep (V) = 0.77 + 0.052 �logðn) (r 2 = 0.996); (where a represents the electron transfer coefficient) and found to be (1.92�2).…”

Electrochemical sensor based on a poly-murexide modified carbon paste electrode for determination of fluoroquinolone antibiotic ciprofloxacin

“…However, despite their high sensitivity and precision, these methods take a long time to implement and require expensive and intricate equipment. Electroanalytical methods have recently been widely used for sensing electroactive pharmaceutical compounds due to many advantages, including low instrumental costs and simplicity and reliability of the methods, as well as their practical sensitivity with low detection limits and a wide dynamic range (Assaf et al, 2021;Rabie et al, 2019;Toghan et al, 2019;Toghan, Abou-Krisha, et al, 2021;Toghan, Gadow, et al, 2021). Chemical modification of the electrodes can improve the electrochemical detection of electroactive substances.…”