Adsorptive stripping voltammetric determination of chloramphenicol residues in milk samples using reduced graphene oxide sensor

Electrochemistry of chloramphenicol on laser-induced graphene electrodes and its voltammetric determination in honey

Laser scribing is a promising technology for the rapid and large-scale production of low-cost electrochemical sensors from diverse substrates. Polyimide has been the most popular so far because of its low cost, flexibility and capability of generating high-quality porous graphene films, known as laser-induced graphene (LIG). Herein we report the electrochemistry of chloramphenicol (CAP) on LIG electrodes and its determination in honey samples. LIG electrodes were fabricated by the photothermal conversion of sp3 carbon within the polymeric matrix into sp2 carbon using a CO2 laser cutter. The LIG electrode associated with differential pulse voltammetry (DPV) showed good linearity (R2 > 0.99) in the range from 10 to 160 μmol L-1 with a limit of detection of 1.0 μmol L-1 and good precision (RSD < 5%) for the electrochemical reduction of CAP species. Detection was possible free from the interference of other antibiotics, such as amoxicillin, tetracycline, sulfanilamide, and sulfamethoxazole. Spiked honey samples were analyzed by the standard-addition method and recovery values between 86 and 109% were obtained, which confirmed the absence of sample matrix effects. Therefore, the proposed sensor is an alternative, feasible, low-cost, and powerful analytical tool for the determination of CAP in honey.

MoS2_CNTs_aerogel-based PEDOT nanocomposite electrochemical sensor for simultaneous detection of chloramphenicol and furazolidone in food samples

Toxic intermediates in food caused by chloramphenicol (CP) and furazolidone (FZ) have gained interest in research toward their detection. Hence, fast, reliable, and accurate detection of CP and FZ in food products is of utmost importance. Here, a novel molybdenum disulfide-connected carbon nanotube aerogel/poly (3,4-ethylenedioxythiophene) [MoS2/CNTs aerogel/PEDOT] nanocomposite materials are constructed and deposited on the pretreated carbon paste electrode (PCPE) by a facile eletropolymerization method. The characterization of MoS2/CNTs aerogel/PEDOT nanocomposite was analyzed by scanning electron microscopy (SEM), cyclic voltammetry, and differential pulse voltammetry. The modified MoS2/CNTs aerogel/PEDOT nanocomposite has improved sensing characteristics for detecting CP and FZ in PBS solution. For this work, we have studied various parameters like electrocatalytic activity, the effect of scan rates, pH variation studies, and concentration variation studies. Under optimum conditions, the modified electrode exhibited superior sensing ability compared to the bare and pretreated CPE. This improvement in electrocatalytic activity can be the higher conductivity, larger surface area, increased heterogeneous rate constant, and presence of more active sites in the MoS2/CNTs aerogel/PEDOT nanocomposite. The modified electrode demonstrated distinct electrochemical sensing toward the individual and simultaneous analysis of CP and FZ with a high sensitivity of 0.701 µA. µM-1 .cm-2 for CP and 0.787 µA. µM-1 .cm-2 for FZ and a low detection limit of 3.74 nM for CP and 3.83 nM for FZ with good reproducibility, repeatability, and interferences. Additionally, the prepared sensor effectively detects CP and FZ in food samples (honey and milk) with an acceptable recovery range and a relative standard deviation below 4%.

CO2-plasma surface treatment of graphite sheet electrodes for detection of chloramphenicol, ciprofloxacin and sulphanilamide

Graphite sheet (GS) electrodes are flexible and versatile substrates for sensing electrochemical; however, their use has been limited to incorporate (bio)chemical modifiers. Herein, we demonstrated that a cold (low temperature) CO2 plasma treatment of GS electrodes provides a substantial improvement of the electrochemical activity of these electrodes due to the increased structural defects on the GS surface as revealed by Raman spectroscopy (ID/IG ratio), and scanning electron microscopy images. XPS analyses confirmed the formation of oxygenated functional groups at the GS surface after the plasma treatment that are intrinsically related to the substantial increase in the electron transfer coefficient (K0 values increased from 1.46 × 10-6 to 2.09 × 10-3 cm s-1) and with reduction of the resistance to charge transfer (from 129.8 to 0.251 kΩ). The improved electrochemical activity of CO2-GS electrodes was checked for the detection of emerging contaminant species, such as chloramphenicol (CHL), ciprofloxacin (CIP) and sulphanilamide (SUL) antibiotics, at around + 0.15, + 1.10 and + 0.85 V (versus Ag/AgCl), respectively, by square wave voltammetry. Limit of detection values in the submicromolar range were achieved for CHL (0.08 μmol L-1), CIP (0.01 μmol L-1) and SFL (0.11 μmol L-1), which enabled the sensor to be successfully applied to natural waters and urine samples (recovery values from 85 to 119%). The CO2-GS electrode is highly stable and inexpensive ($0.09 each sensor) and can be easily inserted in portable 3D printed cells for environmental on-site analyses.

A review on nanomaterial-based electrodes for the electrochemical detection of chloramphenicol and furazolidone antibiotics

To grow food for people, antibiotics were used, and these antibiotics can accumulate in the human body through food metabolism, which may have remarkably harmful effects on human health and safety. Therefore, low-cost sensors are needed for the detection of antibiotic residues in food samples. Recently, nanomaterial-based electrochemical sensors such as carbon nanoparticles, graphene nanoparticles, metal oxide nanoparticles, metal nanoparticles, and metal-organic nanostructures have been successfully used as sensing materials for the detection of chloramphenicol (CP) and furazolidone (FZ) antibiotics. However, additional efforts are still needed to fabricate effective multi-functional nanomaterial-based electrodes for the preparation of portable electrochemical sensor devices. The current review focuses on a quick introduction to CP and FZ antibiotics, followed by an outline of the current electrochemical analytical methods. In addition, we have discussed in-depth different nanoparticle supports for the electrochemical detection of CP and FZ in different matrices such as food, environmental, and biological samples. Finally, a summary of the current problems and future perspectives in this area are also highlighted.

Recent developments on graphene and its derivatives based electrochemical sensors for determinations of food contaminants

The sensing of food contaminants is essential to prevent their adverse health effects on the consumers. Electrochemical sensors are promising in the determination of electroactive analytes including food pollutants, biomolecules etc. Graphene nanomaterials offer many benefits as electrode material in a sensing device. To further improve the analytical performance, doped graphene or derivatives of graphene such as reduced graphene oxide and their nanocomposites were explored as electrode materials. Herein, the advancements in graphene and its derivatives-based electrochemical sensors for analysis of food pollutants were summarized. Determinations of both organic (food colourants, pesticides, drugs, etc.) and inorganic pollutants (metal cations and anions) were considered. The influencing factors including nature of electrode materials and food pollutants, pH, electroactive surface area etc., on the sensing performances of modified electrodes were highlighted. The results of pollutant detection in food samples by the graphene-based electrode have also been outlined. Lastly, conclusions and current challenges in effective real sample detection were presented.

Past and Present of Electrochemical Sensors and Methods for Amphenicol Antibiotic Analysis

Amphenicols are broad-spectrum antibiotics. Despite their benefits, they also present toxic effects and therefore their presence in animal-derived food was regulated. Various analytical methods have been reported for their trace analysis in food and environmental samples, as well as in the quality control of pharmaceuticals. Among these methods, the electrochemical ones are simpler, more rapid and cost-effective. The working electrode is the core of any electroanalytical method because the selectivity and sensitivity of the determination depend on its surface activity. Therefore, this review offers a comprehensive overview of the electrochemical sensors and methods along with their performance characteristics for chloramphenicol, thiamphenicol and florfenicol detection, with a focus on those reported in the last five years. Electrode modification procedures and analytical applications of the recently described devices for amphenicol electroanalysis in various matrices (pharmaceuticals, environmental, foods), together with the sample preparation methods were discussed. Therefore, the information and the concepts contained in this review can be a starting point for future new findings in the field of amphenicol electrochemical detection.