Sensitive and selective determination of paracetamol using a composite of carbon nanotubes and nanoparticles of samarium oxide and zirconium oxide

Development of an electrochemical sensor for the quantification of ascorbic acid and acetaminophen in pharmaceutical samples

This work presents the modification of glassy carbon electrodes (GCE) by using a dispersion resulting from the non-covalent functionalization of multi-walled carbon nanotubes (MWCNT) with polyarginine (polyArg). MWCNT-polyArg is used for the quantification of ascorbic acid (AA) in the presence of acetaminophen (APAP) and viceversa. Since ascorbic acid and acetaminophen are strongly absorbed on GCE/MWCNT-polyArg, they can be detected in the presence of 4.0×10-5 M acetaminophen (and 3.0×10-5 M ascorbic acid) by using adsorptive stripping with media exchange and differential pulse voltammetry. Using water as the solvent for the MWCNT dispersion, the result was Z-potential of 0.053 ± 0.006 V. The developed sensor showed excellent specificity, sensitivity, stability and reproducibility compared to previously published sensors. The GCE/MWCNT-polyArg sensor shows a fast response time of ∼5 minutes, low limits of detection and quantification for AA (0.95 and 2.9 μM respectively) and APAP (0.27 and 0.82μM, respectively), high sensitivity of 0.0616 μA/M for AA or APAP 0.240μA/M. It was used to test its practicability by determining the concentration of AA or APAP (AA and APAP) in pharmaceutical samples. Finally, the simultaneous measurement of ascorbic acid and acetaminophen in pharmaceuticals showed a good correlation, with a maximum error and RSD of 4.5 and 5.1 %, respectively.

Sensitive and selective determination of paracetamol in antipyretic children's syrup with a polyglycine modified glassy carbon electrode

A sensitive and selective electrochemical sensor for the determination of paracetamol (acetaminophen) is proposed based on a polyglycine-coated glassy carbon electrode. The electrochemical behavior of paracetamol was studied by cyclic voltammetry and differential pulse voltammetry. Under optimal experimental conditions, the peak oxidation current of paracetamol increases linearly in the range of 0.5-75 μM. The limit of detection of paracetamol was 0.03 μM and the limit of quantitation was 0.09 μM. In addition, modified glassy carbon with polyglycine as the sensor was successfully used for the determination of paracetamol in antipyretic children's syrup samples, with a recovery rate of over 95.3%, showing its great application potential in drug analysis.

NO2 Sensing Behavior of Compacted Chemically Treated Multi-Walled Carbon Nanotubes

This article is devoted to the investigation of the sensing behavior of chemically treated multi-walled carbon nanotubes (MWNTs) at room temperature. Chemical treatment of MWNTs was carried out with a solution of either sulfuric or chromic acids. The materials obtained were investigated by transmission electron microscopy, scanning electron microscopy, Raman-spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The active layer of chemiresistive gas sensors was obtained by cold pressing (compaction) at 11 MPa of powders of bare and treated multi-walled carbon nanotubes. The sensing properties of pellets were investigated using a custom dynamic type of station at room temperature (25 ± 2 °C). Detection of NO₂ was performed in synthetic air (79 vol% N₂, 21 vol% O₂). It was found that the chemical treatment significantly affects the sensing properties of multi-walled carbon nanotubes, which is indicated by increasing the response of the sensors toward 100-500 ppm NO₂ and lower concentrations.

Novel Self-assembly Pd(II)-Schiff Base Complex Modified Glassy Carbon Electrode for Electrochemical Detection of Paracetamol

A self-assembly Pd-Schiff base complex was synthesized and used as an electrochemical sensor in phosphate buffer solution, where it enhanced the electrocatalytic activity toward the paracetamol detection. The Schiff base {(HL) = (4-(((Z)-3-(hydroxyimino) butan-2-ylidene) amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one)} was selected to prepare Pd-based complexes due to its high antimicrobial activity. A linear calibration curve was constructed using GC/Pd-SB in paracetamol concentration range of 1–50 μM and its detection limit was calculated as 0.067 μM. The modified electrode, GC/Pd-SB, could successfully determine the paracetamol concentration in human blood serum and commercial drug tablets with high sensitivity. The prepared metal complex was characterized using techniques, namely, X-ray diffraction (XRD) and scanning electron microscope (SEM). In addition, electrochemical studies were performed using different electrochemical techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). DFT calculations were used to estimate the equilibrium geometry, molecular orbital, ground-state properties, and interaction energy between paracetamol and palladium.

Graphical Abstract

PAA/ZnO Raspberry-Shaped Composite Microspheres Decorated with Ag Nanoparticles as Cleanable SERS Substrates

A PAA/ZnO/Ag heterostructure composite material was prepared by a reduction method. The properties of composite particles are analyzed by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), UV-visible spectroscopy, and Raman spectroscopy. Ag nanoparticles play an important role in PAA/ZnO/Ag composite microspheres, conferring new SERS properties and functions to PAA/ZnO/Ag. The intensity of the SERS signal of PAA/ZnO/Ag irradiated with UV light decreased from 10 000 to below 500. The SERS detection limit of R6G obtained was reduced to 1 × 10^-6 M. The PAA/ZnO/Ag composite particles show a very good degradation effect on R6G under UV light irradiation. This study has developed a new synthesis method to prepare SERS signal enhancement materials with self-cleaning effects. According to the experimental results, the PAA/ZnO/Ag composite material has higher sensitivity than the PAA/ZnO composite material.