Simultaneous Electrochemical Determination of Paracetamol and Diclofenac Based on Poly(diallyldimethylammonium chloride) Functionalized Graphene

Polyester resin and graphite flakes: turning conductive ink to a voltammetric sensor for paracetamol sensing

The development of a disposable electrochemical paper-based analytical device (ePAD) is described using a novel formulation of conductive ink that combines graphite powder, polyester resin, and acetone. As a proof of concept, the proposed sensor was utilized for paracetamol (PAR) sensing. The introduced ink was characterized via morphological, structural, and electrochemical analysis, and the results demonstrated appreciable analytical performance. The proposed ePAD provided linear behavior (R² = 0.99) in the concentration range between 1 and 60 µmol L^-1, a limit of detection of 0.2 µmol L^-1, and satisfactory reproducibility (RSD ~ 7.7%, n = 5) applying a potential of + 0.81 V vs Ag at the working electrode. The quantification of PAR was demonstrated in different pharmaceutical formulations. The achieved concentrations revealed good agreement with the labeled values, acceptable accuracy (101% and 106%), and no statistical difference from the data obtained by HPLC at the 95% confidence level. The environmental impact of the new device was assessed using AGREE software, which determined a score of 0.85, indicating that it is eco-friendly. During the pharmacokinetic study of PAR, it was found that the drug has a maximum concentration of 23.58 ± 0.01 µmol L^-1, a maximum time of 30 min, and a half-life of 2.15 h. These results are comparable to other studies that utilized HPLC. This suggests that the combination of graphite powder and polyester resin can transform conductive ink into an effective ePAD that can potentially be used in various pharmaceutical applications.

Enhanced Acetaminophen Electrochemical Sensing Based on Nitrogen-Doped Graphene

Because of the widespread acetaminophen usage and the danger of harmful overdosing effects, developing appropriate procedures for its quantitative and qualitative assay has always been an intriguing and fascinating problem. A quick, inexpensive, and environmentally friendly approach based on direct voltage anodic graphite rod exfoliation in the presence of inorganic salt aqueous solution ((NH₄)₂SO₄-0.3 M) has been established for the preparation of nitrogen-doped graphene (exf-NGr). The XRD analysis shows that the working material appears as a mixture of few (76.43%) and multi-layers (23.57%) of N-doped graphenes. From XPS, the C/O ratio was calculated to be 0.39, indicating a significant number of structural defects and the existence of multiple oxygen-containing groups at the surface of graphene sheets caused by heteroatom doping. Furthermore, the electrochemical performances of glassy carbon electrodes (GCEs) modified with exf-NGr for acetaminophen (AMP) detection and quantification have been assessed. The exf-NGr/GCE-modified electrode shows excellent reproducibility, stability, and anti-interfering characteristics with improved electrocatalytic activity over a wide detection range (0.1-100 µM), with a low limit for AMP detection (LOD = 3.03 nM). In addition, the developed sensor has been successfully applied in real sample analysis for the AMP quantification from different commercially available pharmaceutical formulations.

A bibliometric analysis of graphene in acetaminophen detection: Current status, development, and future directions

Acetaminophen is a widely used analgesic throughout the world. Detection of acetaminophen has particular value in pharmacy and clinics. Electrochemical sensors assembled with advanced materials are an effective method for the rapid detection of acetaminophen. Graphene-based carbon nanomaterials have been extensively investigated for potential analytical applications in the last decade. In this article, we selected papers containing both graphene and acetaminophen. Bibliometrics was used to analyze the relationships and trends among these papers. The results show that the topic has grown at a high rate since 2009. Among them, the detection of acetaminophen by an electrochemical sensor based on graphene is the most important direction. Graphene has moved from being a primary sensing material to a substrate for immobilization of other active ingredients. In addition, the degradation of acetaminophen using graphene-modified electrodes is also an important direction. We analyzed the research history and current status of this topic through bibliometrics. Authors, institutions, countries, and key literature were discussed. We also proposed perspectives for this topic.

Effects of poly(diallyldimethylammonium chloride) addition on the curing kinetics of urea-formaldehyde adhesives for particleboards

Addition of poly(diallyldimethylammonium chloride) (PDDA) on the performances of urea-formaldehyde (UF) adhesives was evaluated in this work. Three types of UF adhesives were prepared, one without PDDA addition, and two types with PDDA addition of 1 and 3 wt.% per dry UF adhesive mass. These UF adhesive systems were used for producing experimental particleboard panels. The addition of PDDA decreased the thickness swelling of the panel samples, while the internal bond of the particleboards increased significantly only at the highest PDDA content (3 wt.%). Differential scanning calorimetry (DSC) was applied to address the influence of PDDA on UF adhesive curing kinetics. DSC scans were performed in non-isothermal regimes using different heating rates (5, 10, and 20 ?C?min?1). The activation energy (Ea) of the curing reaction showed slightly lower values for the UF adhesive systems containing PDDA. However, the peak temperatures and enthalpy of reaction did not change significantly. The Kissinger-Akahira-Sunose and Friedman iso-conversional methods were applied to investigate the effects of PDDA addition on the UF adhesive curing process.

Electrochemical Method for Ease Determination of Sodium Diclofenac Trace Levels in Water Using Graphene-Multi-Walled Carbon Nanotubes Paste Electrode

Sodium diclofenac (DCF) presence reported in water use cycle at various concentrations including trace levels necessitates continuous development of advanced analytical method for its determination. In this work, ease electrochemical methods for DCF determination based on voltammetric and amperometric techniques were proposed using a simple combination of graphene with multi-walled carbon nanotubes as paste electrode. Integration of the graphene with multi-walled carbon nanotubes enlarged the electroactive surface area of the electrode and implicitly enhanced the electrochemical response for DCF determination. On the basis of the sorption autocatalytic effect manifested at low concentration of DCF, we found that the preconcentration step applied prior to differential-pulsed voltammetry (DPV) and multiple-pulsed amperometry (MPA) allowed for the enhancement of the electroanalytical performance of the DCF electrochemical detections, which were validated by testing in tap water. The lowest limit of detection (LOD) of 1.40 ng·L⁻¹ was found using preconcentration prior to DPV under optimized operating conditions, which is better than that reached by other carbon-based electrodes reported in the literature.

Simultaneous Analysis of Paracetamol and Diclofenac Using MWCNTs-COOH Modified Screen-Printed Carbon Electrode and Pulsed Potential Accumulation

A differential-pulse adsorptive stripping voltammetric (DPAdSV) procedure with the use of pulsed potential accumulation and carboxyl functionalized multiwalled carbon nanotubes modified screen-printed carbon electrode (SPCE/MWCNTs-COOH) was delineated for simultaneous analysis of paracetamol (PA) and diclofenac (DF). The use of carboxyl functionalized MWCNTs and pulsed potential accumulation improves the analytical signals of PA and DF, and minimizes interferences from surfactants. After optimization of analytical conditions for this sensor, the peak currents of the two compounds were found to increase linearly with the increase in their concentration (5.0 × 10^-9-5.0 × 10^-6 mol L^-1 with a detection limit of 1.4 × 10^-9 mol L^-1 for PA, and 1.0 × 10^-10-2.0 × 10^-8 mol L^-1 with a detection limit of 3.0 × 10^-11 mol L^-1 for DF). For the first time, the electrochemical sensor allows simultaneous determination of PA and DF at concentrations of 24.3 ± 0.5 nmol L^-1 and 3.7 ± 0.7 nmol L^-1, respectively, in wastewater samples purified in a sewage treatment plant.

Application of Nanostructured Carbon-Based Electrochemical (Bio)Sensors for Screening of Emerging Pharmaceutical Pollutants in Waters and Aquatic Species: A Review

Pharmaceuticals, as a contaminant of emergent concern, are being released uncontrollably into the environment potentially causing hazardous effects to aquatic ecosystems and consequently to human health. In the absence of well-established monitoring programs, one can only imagine the full extent of this problem and so there is an urgent need for the development of extremely sensitive, portable, and low-cost devices to perform analysis. Carbon-based nanomaterials are the most used nanostructures in (bio)sensors construction attributed to their facile and well-characterized production methods, commercial availability, reduced cost, high chemical stability, and low toxicity. However, most importantly, their relatively good conductivity enabling appropriate electron transfer rates-as well as their high surface area yielding attachment and extraordinary loading capacity for biomolecules-have been relevant and desirable features, justifying the key role that they have been playing, and will continue to play, in electrochemical (bio)sensor development. The present review outlines the contribution of carbon nanomaterials (carbon nanotubes, graphene, fullerene, carbon nanofibers, carbon black, carbon nanopowder, biochar nanoparticles, and graphite oxide), used alone or combined with other (nano)materials, to the field of environmental (bio)sensing, and more specifically, to pharmaceutical pollutants analysis in waters and aquatic species. The main trends of this field of research are also addressed.

First Electrochemical Sensor (Screen-Printed Carbon Electrode Modified with Carboxyl Functionalized Multiwalled Carbon Nanotubes) for Ultratrace Determination of Diclofenac

A simple, sensitive and time-saving differential-pulse adsorptive stripping voltammetric (DPAdSV) procedure using a screen-printed carbon electrode modified with carboxyl functionalized multiwalled carbon nanotubes (SPCE/MWCNTs-COOH) for the determination of diclofenac (DF) is presented. The sensor was characterized using optical profilometry, SEM, and cyclic voltammetry (CV). The use of carboxyl functionalized MWCNTs as a SPCE modifier improved the electron transfer process and the active surface area of sensor. Under optimum conditions, very sensitive results were obtained with a linear range of 0.1–10.0 nmol L⁻¹ and a limit of detection value of 0.028 nmol L⁻¹. The SPCE/MWCNTs-COOH also exhibited satisfactory repeatability, reproducibility, and selectivity towards potential interferences. Moreover, for the first time, the electrochemical sensor allows determining the real concentrations of DF in environmental water samples without sample pretreatment steps.

One-pot synthesis of a CdS-reduced graphene oxide-carbon nitride composite for self-powered photoelectrochemical aptasensing of PCB72

Graphitic carbon nitride (C3N4) is a carbon-based metal-free semiconductor, which has been widely explored as a photoactive material. In this work, the CdS, reduced graphene oxide (rGO) and C3N4 (CdS-rGO-C3N4) composite was synthesized by a simple one-pot hydrothermal method and utilized to construct a photoelectrochemical (PEC) sensor. Compared with CdS, C3N4 and CdS-C3N4, the CdS-rGO-C3N4 composite exhibited enhanced photoelectrochemical (PEC) performance, due to the expanded absorption of C3N4 in the visible region by CdS and promoted the charge carrier separation of a photoelectrode by rGO. Based on a glassy carbon electrode (GCE) modified with CdS-rGO-C3N4 and a PCB72-binding aptamer (ap/CdS-rGO-C3N4/GCE), a PEC aptasensor for the detection of 2,3',5,5'-tetrachlorobiphenyl (PCB72) was developed. When H2O2 was added into the electrolyte, the PEC sensor exhibited an amplified response toward PCB72, and could be operated in a self-powered mode at a potential of 0 V. Under optimum conditions, the constructed PEC aptasensor exhibited a wide linear range of 10 to 1000 ng mL-1 for PCB72 detection, with a low detection limit (S/N = 3) of 1.0 ng mL-1. Moreover, this aptasensor exhibited high selectivity, good reproducibility and high stability. The applicability of the developed PEC strategy was demonstrated by determining PCB72 in environmental water.

Taking advantage of CTAB micelles for the simultaneous electrochemical quantification of diclofenac and acetaminophen in aqueous media

Cetyltrimethylammonium bromide hemimicelles, formed on the surfaces of a carbon paste electrode, selectively adsorbed diclofenac molecules from a neutral aqueous solution containing acetaminophen, allowing simultaneous quantification of both drugs.