Synthesis and Introducing Au-Cu Alloy Nanoparticles/Porous Silicon as a Novel Modifier of Screen Printed Carbon Electrode in Simultaneous Electrocatalytic Detection of Codeine and Acetaminophen

In the present study, a bimetallic nanostructure of gold-copper (Au-CuNPs) was decorated on the surface of porous silicon (PSi) using an easy galvanic replacement reaction between metal ions and PSi in the presence of 0.1 M hydrofluoric acid solution. The morphology and structures of the Au-CuNPs@PSi nanocomposite were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) energy-dispersive X-ray spectroscopy (EDX) and cyclic voltammetry (CV) techniques. Then, prepared nanocomposite was used as a modifier in screen-printed carbon electrode (SPCE) for the highly sensitive simultaneous determination of codeine (COD) and acetaminophen (ACE). The combination of PSi and metals nanoparticles provide a porous and high surface area with excellent electrical conductivity which leads to reduce the peak potentials and enhance the oxidation peak currents of COD and ACE at the surface of the Au-CuNPs@PSi/SPCE nanosensor. The dynamic linear ranges were obtained from 0.06 to 0.6 µM for both COD and ACE and the detection limits (3.0 S/N) estimated 0.35 µM for COD and 0.30 µM for ACE, respectively. Moreover, recovery tests were carried out in real samples such as urine, human blood plasma, and tablets.

Electrochemical sensor based on screen printed carbon electrode–zinc oxide nano particles/molecularly imprinted-polymer (SPCE–ZnONPs/MIP) for detection of sodium dodecyl sulfate (SDS)

The foremost objective of this work is to prepare a novel electrochemical sensor-based screen-printed carbon electrode made of zinc oxide nanoparticles/molecularly imprinted polymer (SPCE–ZnONPs/MIP) and investigate its characteristics to detect sodium dodecyl sulfate (SDS).

Graphene oxide modified screen-printed electrode for highly sensitive and selective electrochemical detection of ciprofloxacin residues in milk

The monitoring of antibiotic residues in foodstuffs by using rapid detection method is essential for food safety. In this work, the electrochemical sensor was developed by modification of screen-printed carbon electrode with graphene oxide, and then the ciprofloxacin (CIP) was detected based on the complexation of CIP with Mn2+. On modified electrode, the anodic stripping peak current response of Mn2+ was prohibited in the presence of CIP, and a peak current response of the complex was occurred. Thus, the peak current response of the complexation peak was employed as the indicating signal for CIP determination, which was more sensitive than the direct electrochemical oxidation response of CIP. Parameters that affect the signal response have been investigated in method. Under the optimum conditions, the peak current of the complexation peak was linearly correlated with the CIP content in the milk sample solution at 1.0 to 8.0 μM, and the linear correlation coefficients (R2) was 0.994. The limits of detection (LOD) was 0.30 μM. Recoveries of CIP in milk sample were ranged from 81.0 to 95.4% with relative standard deviations (RSDs) below 4.6%. The method showed high selectivity and sensitive, good reproducibility, indicated that this method has potential to be applied in CIP residue analysis.

Smartphone-based molecularly imprinted sensors for rapid detection of thiamethoxam residues and applications

In order to achieve rapid detection of thiamethoxam residues in mango, cowpea and water, this study modified the screen printed carbon electrode (SPCE) to make a specific molecular imprinting sensor (Thiamethoxam-MIP/Au/rGO/SPCE) for thiamethoxam. An integrated smartphone platform was also built for thiamethoxam residue analysis. The performance of the complete system was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The system was then applied for the rapid determination of thiamethoxam residues in water, mango and cowpea samples. The results showed that the molecular sensor showed good linearity in the range 0.5–3.0 μmol/L of thiamethoxam. The detection limit of thiamethoxam was 0.5 μmol/L. Moreover, the sensor had good reproducibility and anti-interference performance. The average recovery rates of the pesticide residues in water, mango and cowpea samples were in the range of 90–110% with relative standard deviations < 5%. The rapid detection system for thiamethoxam residue constructed in this study was simple, reliable, reproducible and had strong anti-interference. It has broad application prospects in the field detection of thiamethoxam residue, and serves as a valuable reference for the further development of rapid detection technology of pesticide residues in the field of environment and food safety.

Development of a New Screen-Printed Transducer for the Electrochemical Detection of Thiram

A new transducer based on a screen-printed carbon electrode has been developed for the quantification of thiram. Detection of this fungicide is based on the performance of two enzymes: (1) aldehyde dehydrogenase catalyzes the aldehyde oxidation using NAD+ as a cofactor and simultaneously, (2) diaphorase reoxidizes the NADH formed in the first enzymatic process due to the presence of hexacyanoferrate(III) which is reduced to hexacyanoferrate(II). Taking into account that aldehyde dehydrogenase is inhibited by thiram, the current decreases with pesticide concentration and thiram can be electrochemically quantified below legal limits. The transducer proposed in this work involves the modification of the carbon WE with the co-factors (NAD+ and hexacyanoferrate(III)) required in the enzymatic system. The new device employed in this work allows the detection of 0.09 ppm thiram, a concentration below legal limits (Maximum Residue Limits 0.1–10 ppm).

Electrochemically Activated Screen-Printed Carbon Electrode for Determination of Ibuprofen

In this study, we present a simple, sensitive and selective analytical procedure for the ibuprofen (IBP) analysis using the commercially available screen-printed carbon electrode electrochemically activated (aSPCE) by cyclic voltammetry in 0.1 M NaOH. The quantitative determinations of IBP were carried out in 0.25 M acetate buffer solution of pH 4.5 ± 0.1 using the differential-pulse voltammetry (DPV). Different experimental parameters for DPV analysis were optimized, including pH and concentration of supporting electrolyte, amplitude (ΔEA), scan rate (ν) and modulation time (tm). The linear ranges of calibration curve were from 0.50–20.0 and 20.0–500.0 µM. The detection and quantification limits were estimated to be 0.059 and 0.20 µM. The aSPCE displayed satisfactory repeatability, reproducibility, and selectivity. Furthermore, the DPV procedure with the use of aSPCE was used to determination of IBP in pharmaceutical formulations. The results achieved by DPV show satisfactory agreement with those obtained by manufacturers (the relative errors are in the range of 3.1–4.7%).