In this study, an in situ synthesis approach based on electrochemical reduction and ion exchange was employed to detect carbaryl species using a disposable, screen-printed carbon electrode fabricated with nanocomposite materials. Reduced graphene oxide (rGO) was used to create a larger electrode surface and more active sites. Gold nanoparticles (AuNPs,) were incorporated to accelerate electron transfer and enhance sensitivity. A cation exchange Nafion polymer was used to enable the adhesion of rGO and AuNPs to the electrode surface and speed up ion exchange. Cyclic voltammetry (CV), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), electrical impedance spectroscopy (EIS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were performed to study the electrochemical and physical properties of the modified sensor. In the presence of differential pulse voltammetry (DPV), an rGO/AuNP/Nafion-modified electrode was effectively used to measure the carbaryl concentration in river and tap water samples. The developed sensor exhibited superior electrochemical performance in terms of reproducibility, stability, efficiency and selectivity for carbaryl detection with a detection limit of 0.2 µM and a concentration range between 0.5µM and 250 µM. The proposed approach was compared to capillary electrophoresis with ultraviolet detection (CE-UV).

Recently, non-steroidal anti-inflammatory drugs (NSAIDs) have been increasingly used in humans and animals.

A simple, rapid method using CE and microchip electrophoresis with C⁴D has been developed for the separation of four nonsteroidal anti‐inflammatory drugs (NSAIDs) in the environmental sample. The investigated compounds were ibuprofen (IB), ketoprofen (KET), acetylsalicylic acid (ASA), and diclofenac sodium (DIC). In the present study, we applied for the first time microchip electrophoresis with C⁴D detection to the separation and detection of ASA, IB, DIC, and KET in the wastewater matrix. Under optimum conditions, the four NSAIDs compounds could be well separated in less than 1 min in a BGE composed of 20 mM His/15 mM Tris, pH 8.6, 2 mM hydroxypropyl‐beta‐cyclodextrin, and 10% methanol (v/v) at a separation voltage of 1000–1200 V. The proposed method showed excellent repeatability, good sensitivity (LODs ranging between 0.156 and 0.6 mg/L), low cost, high sample throughputs, portable instrumentation for mobile deployment, and extremely lower reagent and sample consumption. The developed method was applied to the analysis of pharmaceuticals in wastewater samples with satisfactory recoveries ranging from 62.5% to 118%.

Polychlorinated biphenyls (PCBs) have been found in soil, which has typically been the result of industrial pollution in the past two decades. Although they are banned, PCBs can still be found in soils and other environmental media. For this reason, it is critical to develop an analytical method that can reliably identify and monitor their sources. This study describes a gas chromatography with mass spectrometry (GC-MS) technique, which was used to detect PCBs in soil samples by using a fast extraction method. Using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, PCBs were more effectively extracted from soil. Different related parameters, such as time of shaking and centrifuging, type of solvent, and clean-up adsorbents, were compared and optimized. As the extraction solvent, acetonitrile/water produced the best results, and as the dispersive solid-phase extraction sorbent, diatomaceous earth produced the best results. Procedures allowed recovery values between 95.3% and 103.2%. A limit of detection of 1.9 µg/kg was determined with relative standard deviations (n = 3) of 2.1–4.0% for intra-day assays and 3.6–5.8% for inter-day assays. It was demonstrated that the method was simple, sensitive, efficient, and environmentally friendly when applied to soil samples. To our knowledge, an integrated approach based on QuEChERS for the determination of Aroclor 1254 in soil has not been published before. It is believed that this approach will eliminate the significant challenge of sample extraction in GC-MS processing, which was considered to be a procedural challenge in previous analyses.

PCBs (polychlorinated biphenyls) are a very large group of organic compounds that have between two and ten chlorine atoms attached to the biphenyl. These compounds have an acute impact as environmental pollutants, causing cancer and other adverse health effects in humans. It is therefore imperative to develop techniques for the cost-effective detection of PCBs at very low concentrations in ecosystems. In this paper, a novel label-free, indirect, competitive electrochemical immunosensor was first developed with a PCB-BSA conjugate. It is shown herein to compete with free PCBs for binding to the anti-PCB polyclonal primary antibody (IgY). Then, we used a secondary antibody to enhance the sensitivity of the sensor for the detection of PCB in a sample. It has been successfully immobilized on an 11-mercaptoundecanoic acid (11-MUA)-modified gold electrode via a carbodiimide-coupling reaction using cross-linking 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) on the electrode surface. The immunosensor was investigated by cyclic voltammetry and differential pulse voltammetry in a standard solution of [Fe(CN)₆]^3−/4−. A linear range of 0.011–220 ng/mL⁻¹ and a limit of detection (LOD) of 0.11 ng/mL⁻¹ for PCBs detection were achieved by the developed immunosensor, showing advantages over conventional assays. The novel label-free electrochemical immunosensor discussed in this paper is a solution for simple, rapid, cost-effective sample screening in a portable, disposable format. The proposed immunosensor has good sensitivity, and it can prove to be an adequate real-time monitoring solution for PCBs in soil samples or other samples.