Green Synthesis of Gold Nanoparticles Using Peach Extract Incorporated in Graphene for the Electrochemical Determination of Antioxidant Butylated Hydroxyanisole in Food Matrices

Chitosan-Based Hydrogel Functionalized with Fe(II) Phthalocyanine for Butylated Hydroxyanisole Determination

The synthesis of functional electrode sensing materials is the key to the construction of electrochemical sensors. A new hydrogel electrode sensing material was developed by incorporating Fe(II) phthalocyanine (FePc) into chitosan-based hydrogels. The chitosan-based hydrogel plays a crucial role in dispersing FePc nanoparticles uniformly and generating a stable environment for the redox reaction of butylated hydroxyanisole (BHA) on the electrode surface. Under optimized conditions, the prepared electrochemical sensor exhibited a detection range of 0.1-30 and 30-1000 μmol/L, with a detection limit of 0.035 μmol/L (S/N = 3). Moreover, this sensor demonstrated exceptional resistance to interference and maintained its stability. These findings suggest that the developed electrochemical sensor is promising for reliable detection of BHA in real samples, highlighting the potential of combining conductive hydrogels with functionalized metal phthalocyanines for accurate and rapid BHA determination.

Electrochemical needle sensor based on a B, N co-doped graphene microelectrode array for the on-site detection of salicylic acid in fruits and vegetables

In this study, a microelectrode array sensor based on boron and nitrogen co-doped vertical graphene (BNVG) was assembled to quantify salicylic acid (SA) in living plants. The influence of B and N contents on the electrochemical reaction kinetics and SA response signal was investigated. A microneedle sensor with three optimized BNVG microelectrodes (3.57 at.% B and 3.27 at.% N) was used to quantitatively analyze SA in the 0.5-100 μM concentration range and pH 4.0-9.0, with limits of detection of 0.14-0.18 μM. Additionally, a quantitative electrochemical model database based on the BNVG microelectrode sensor was constructed to monitor the growth of cucumbers and cauliflowers, which confirmed that the SA level and plant growth rate were positively correlated. Moreover, the SA levels in various vegetables and fruits purchased from the market were measured to demonstrate the practical application prospects for on-site inspection and evaluation.

Heparin-stabilized gold nanoparticles embedded in graphene for the electrochemical determination of esculetin

A conductive nanocomposite consisting of heparin-stabilized gold nanoparticles embedded in graphene was prepared and characterized to develop an electrochemical sensor for the determination of esculetin in tea and jam samples. The gold nanoparticles were characterized by spectroscopic and microscopic techniques. The different proportions of graphene in the nanocomposite were evaluated and characterized by electrochemical practices. The heterostructure material on the glassy carbon electrode with esculetin showed π-π stacking interactions with an adsorption-controlled process. The voltammetric profile of esculetin using the proposed nanomaterial presented oxidation and reduction peaks at +0.61 and +0.58 V vs. Ag/AgCl, respectively, facilitating the electron transfer with esculetin through the transfer of two moles of protons and two moles of electrons per mole of esculetin. Using optimized conditions and square wave voltammetry, the calibration curve was obtained with two linear ranges, from 0.1 to 20.5 μmol L-1, with a detection limit of 43.0 nmol L-1. The electrochemical sensor showed satisfactory results for repeatability and stability, although interferences were observed in the presence of high concentrations of ascorbic acid or quercetin. The sensor was successfully applied in the determination of esculetin in samples of mulberry jam, white mulberry leaf tea, and white mulberry powder tea, presenting adequate recovery ranges. This directive provides valuable insights for the development of novel electrochemical sensors using heparin-based conductive nanomaterials with improved sensitivity and sensibility.

Screen-Printed Carbon Electrode Modified with Carbon Nanotubes and Copper Film as a Simple Tool for Determination of Trace Concentrations of Lead Ions

A copper film-modified, carboxyl-functionalized, and multi-walled carbon nanotube (MWCNT-COOH)-modified screen-printed carbon electrode (CuF/MWCNTs/SPCE) was used for lead determination using anodic stripping voltammetry. The main parameters were investigated and optimized during the development of the research procedure. The most optimal electrolyte concentrations were determined to be 0.4 M HCl and 6.3 × 10-5 M Cu(II). The optimal parameters for voltammetric stripping measurements are as follows: an accumulation potential of -0.7 V; an accumulation time of 120 s; and a pulse amplitude and pulse time of 120 mV and 2 ms, respectively. The effect of surface active substances and humic substances as potential interferents present in aqueous environmental samples was investigated. The validation of the procedure was carried out using certified reference materials, like waste water SPS-WW1 and environmental matrix TM-25.5. In addition, the developed procedure was applied to investigate lead recovery from natural environmental water, such as rivers and lakes.