Detection of Lead (II) on a Boron-doped Diamond Electrode by Differential Pulse Anodic Stripping Voltammetry

Lead, even in low concentrations, can be dangerous and toxic to humans and their environment. Due to the toxicity of this metal, an electroanalytical method has been developed for the direct quantitative determination of Pb2+. The Pb2+ detection was performed using Differential Pulse Anodic Stripping Voltammetry. The quantification of Pb2+ by these electrochemical methods was carried out on a boron-doped diamondmicro electrode in HNO3 medium (0.01 M). This work made it possible to efficiently detect lead with a detection limit equal to 0.052 μM and a quantification limit equal to 0.173 μM. This method made it possible to selectively detect and quantify the Pb2+ in the presence of other metals such as Cd2+ and Cu2+. In the presence of other metals, a recovery rate of 94.53% was observed. This value is close to the recovery rate obtained (98.6%) when the Pb2+ is alone in electrolyte.

Development of a Novel Sensor Based on Polypyrrole Doped with Potassium Hexacyanoferrate (II) for Detection of L-Tryptophan in Pharmaceutics

This study describes the development of a new sensor with applicability in the determination and quantification of yjr essential amino acid (AA) L-tryptophan (L-TRP) from pharmaceutical products. The proposed sensor is based on a carbon screen-printed electrode (SPCE) modified with the conductor polymer polypyrrole (PPy) doped with potassium hexacyanoferrate (II) (FeCN). For the modification of the SPCE with the PPy doped with FeCN, the chronoamperometry (CA) method was used. For the study of the electrochemical behavior and the sensitive properties of the sensor when detecting L-TRP, the cyclic voltammetry (CV) method was used. This developed electrode has shown a high sensibility, a low detection limit (LOD) of up to 1.05 × 10−7 M, a quantification limit (LOQ) equal to 3.51 × 10−7 M and a wide linearity range between 3.3 × 10−7 M and 1.06 × 10−5 M. The analytical performances of the device were studied for the detection of AA L-TRP from pharmaceutical products, obtaining excellent results. The validation of the electroanalytical method was performed by using the standard method with good results.

A strategy of electrochemical simultaneous detection of acetaminophen and levofloxacin in water based on g-C3N4 nanosheet-doped graphene oxide

A novel electroanalytical method for the simultaneous determination of acetaminophen (AC) and levofloxacin (LEV) in environmental water was proposed based on graphitic carbon nitride nanosheet-doped graphene oxide (CNNS/GO).

Selective Sensing Platform Utilizing Graphitized Multi-Walled Carbon Nanotubes for Monitoring of Ondansetron and Paracetamol

Background: Ondansetron and paracetamol are often co-administrated to prevent and treat nausea and vomiting caused by anaesthesia and to control of postoperative pain. In addition, ondansetron is used as the first-line antiemetic in paracetamol overdose. Therefore, selective and sensitive method for their simultaneous analysis is of a great importance. The electroanalytical methods are highly sensitive and offer many possibilities for new sensor platform design. However, at present, no electroanalytical method for simultaneous determination of these drugs has been proposed. Objective: The aim of this study was to develop a novel nanosensor for selective monitoring of ondansetron and paracetamol in pharmaceutical and biological samples without expensive and time-consuming pretreatments. Methods: The graphitized multi-walled carbon nanotubes embedded in a cation exchange polymer matrix was selected, among various surface functionalizations evaluated, to design novel sensor. Based on its excellent sensing performance, the first electroanalytical method was developed for rapid concurrent determination of investigated drugs. Results: The scanning electron microscopy study showed interlinked nanoporous network structure and highly enlarged active surface. The developed sensor facilitated electron transfer in the oxidation of both drugs and tremendously enhanced the adsorption capacity for ondasetron, thus exhibiting significant increase of drug responses and sensitivity. To obtain much sensitive response of investigated drugs the effect of pH values of supporting electrolyte, dispersed nanomaterial amount, the cation exchange polymer concentration, drop-casting volume of nanocomposite suspension, accumulation potential and deposition time on the peak current was evaluated. The developed electroanalytical method was validated and practical utility of the proposed nanosensor was tested. Conclusion: The developed sensor is promising sensing platform with a fast response time for analysis of ondansetron and paracetamol at very different concentration levels found in their fixed-dose combination and human serum sample after recommended daily doses showing its potential usage in pharmaceutical quality control and clinical research.

Development of a Novel Electrochemical Biosensor Based on Carbon Nanofibers–Gold Nanoparticles–Tyrosinase for the Detection of Ferulic Acid in Cosmetics

The present paper deals with the electrochemical behavior of three types of sensors based on modified screen-printed electrodes (SPEs): a sensor based on carbon nanofibers (CNF/SPE), a sensor based on nanofibers of carbon modified with gold nanoparticles (CNF-GNP/SPE) and a biosensor based on nanofibers of carbon modified with gold nanoparticles and tyrosinase (CNF-GNP-Ty/SPE). To prepare the biosensor, the tyrosinase (Ty) was immobilized on the surface of the electrode already modified with carbon nanofibers and gold nanoparticles, by the drop-and-dry technique. The electrochemical properties of the three electrodes were studied by cyclic voltammetry in electroactive solutions, and the position and shape of the active redox peaks are according to the nature of the materials modifying the electrodes. In the case of ferulic acid, a series of characteristic peaks were observed, the processes being more intense for the biosensor, with the higher sensitivity and selectivity being due to the immobilization of tyrosinase, a specific enzyme for phenolic compounds. The calibration curve was subsequently created using CNF-GNP-Ty/SPE in ferulic acid solutions of various concentrations in the range 0.1–129.6 μM. This new biosensor allowed low values of the detection threshold and quantification limit, 2.89 × 10−9 mol·L−1 and 9.64 × 10−9 mol·L−1, respectively, which shows that the electroanalytical method is feasible for quantifying ferulic acid in real samples. The ferulic acid was quantitatively determined in three cosmetic products by means of the CNF-GNP-Ty/SPE biosensor. The results obtained were validated by means of the spectrometric method in the infrared range, the differences between the values of the ferulic acid concentrations obtained by the two methods being under 5%.

Andrographolide: A Review of Analytical Methods

Bicyclic diterpenoid lactone andrographolide is regarded as a “natural antibiotic” as it is known to exhibit a range of bioactivities including anti-inflammatory, antibacterial, antipyretic, antineoplastic, cardioprotective, hepatoprotective and hypoglycaemic, and is present in Andrographis paniculata. The aim of this article is to review the information on analytical methods for andrographolide in biological samples, pharmaceutical formulations and plant materials. This article includes various techniques such as Spectrophotometry, Chemiluminescence method, Electroanalytical method, Chromatography and various hyphenated techniques.