Analytical and Bioanalytical Chemistry Research
Volume:9 Issue: 2, Spring 2022

A cloud point extraction/solvation method (CPE-SM) based on the use of vitamin C as a chelating agent was developed for the separation and determination of silver in environmental samples. TritonX-100 was used to extract silver ions in aqueous solutions after forming solvation species with vitamin C in the presence of salting-out (0.5 mol L-1 KNO3) at 90 ̊C for 10 minutes. This study evaluated the main parameters affecting the CPE-SM method, such as the kind and concentration of the salting-out, organic reagents, silver ion, temperature, heating time, and volume of surfactant. Under the optimized experimental factors, the calibration curve was linear in the range (0.1 -10 μg/L). The relative standard deviation (RSD) was 1.1-2.9% for n:5 at 1,4,9 μg L-1, a low limit of detection (LOD), and a limit of quantification (LOQ) of 0.035, 0.116 μg L-1 respectively. The accuracy of the method was evaluated by two independent techniques (flame atomic absorption spectrometry – FAAS, and spectrophotometry - using dithizone as a complexing agent). The CPE-SM technique was used to preconcentrate and determine the silver ions in river water, tap water, and soil samples, and the results were favorable and good.

The main objective of this work was to evaluate the feasibility of the application of GO/Na2SiO3 nanocomposite as highly efficient adsorbent for the removal of malachite green as a cationic dye from aqueous solutions. To do so, first the synthesized nanosorbent was characterized via FTIR, SEM, TEM and XRD techniques. Surface area and pore mean size of above mentioned nanocomposite were determined using BET technique. Also, some important parameters affecting the efficiency of the absorption of malachite green, such as pH, adsorbent dosage, contact time, primary concentration of dye and salt effect were optimized. The malachite green (water-soluble) dye was analyzed at a maximum wavelength of 618 nm. The optimal conditions for removal of malachite green from aqueous solution included a 20 mg l-1 initial concentration with 25 mg adsorbent at pH 7, and adsorption equilibrium was achieved within 5 min. Kinetic studies confirmed that dye adsorption process followed pseudo-second order kinetic models (R2 = 0.9999) and adsorption equilibrium data showed good correlation with Freundlich isotherm (R2=0.9982 at 298 K). Thermodynamic analysis indicates that the adsorption process is spontaneous and exothermic in nature. In addition, the experimental data obtained from reusability studies showed that the prepared adsorbent could be used in up to six adsorption-desorption cycles without significant decrease in removal efficiency.

This study used a hydrothermal method to synthesize MoS2 nanosheets (NSs). The study also utilized various analytical procedures to characterize the MoS2 NSs. It has been found that XRD, in particular, gave information on the crystal structure of the MoS2 NSs. These NSs have been visible with SEM. In addition, EDX has been used to scrutinize MoS2 NSs formation. Moreover, MoS2 NSs modified graphite screen printed electrode (MoS2 NSS/GSPE) has been built by dropping the MoS2 NSS onto GSPE for making a voltammetric sensor as well as the evaluation of the morphine voltammetric behavior. Findings showed stronger electro-catalytic oxidation of MoS2 NSS for morphine with a more negative potential. Consequently, the modified electrode enabled the simultaneous detection of diclofenac and morphine with the peak potential at 0.47 V and 0.27 V. Results indicated linear response in a concentration range between 0.05 and 600.0 μM (morphine) with 0.03 μM limit of detection (LOD). Finally, the modified electrode has been substantially utilized for analyzing diclofenac and morphine in the samples of diclophenac tablet, urine, and morphine ampoule with acceptable recovery and accuracy.

Bacterial infection is a global problem, and detection of bacteria is the first step for solving such a problem. Herein, we developed an electrochemical biosensor for the detection of the bacteria Chlamydia Trachomatis. The hybridization-based biosensor was made by modifying the screen-printed gold electrode (SPGE) with the thiolated specific detection probes, which were complementary sequences to the target DNA molecule of the bacteria. The Oracet blue was used as an electrochemical label which was intercalated between two DNA sequences, and its reduction peak current was recorded by DPV method as an output signal of the biosensor. Conventional electrochemical characterization techniques, including cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS), were used to confirm the fabrication of the modified electrode. In addition, the Atomic Force Microscopy (AFM) imaging was performed to assess the electrode surface. The dynamic range of the biosensor was from 4 to 3000 pM with a detection limit of 1.3 pM. The simplicity and performance mentioned above of the biosensor, alongside the low cost and repeatability of the production, make it a great candidate for clinical applications for Chlamydia Trachomatis detection. Plus, it can be used for another species of bacteria with just a change of the thiolated probe.

In this study, new chemiluminescence (CL) method was proposed to determine the amount of remifentanil in pharmaceuticals. We found that the weak CL intensity in the reaction between acidic cerium(IV) and Ru(phen)32+ complex increases significantly in the presence of remifentanil. Effect of remifentanil was investigated in some other CL systems such as luminol-IO4-, direct oxidation using acidic cerium(IV) or acidic KMnO4. Moreover, the effect of different dyes as a sensitizer was investigated in the KMnO4-Dye CL system. The dyes used in this study were crystal violet, amido black, naphthol green, amaranth, rhodamine 6G, safranin, orange G, fluorescein, and chromotrope 2R. The results showed that remifentanil has the highest CL intensity and S/B ratio in the acidic cerium(IV)- Ru(phen)32+ CL system. The reaction mechanism was evaluated by studying the CL reaction kinetics in the presence and absence of remifentanil and spectrophotometric spectra. The results indicate that remifentanil can convert Ru(phen)33+ complex rapidly to Ru(phen)32+* complex, which emits light when it returns to its ground-state. The method's linear dynamic range, detection limit, and reproducibility for four repetitive measurements of 109.39 μg mL-1 were 1.75-145.85, 1.41 μg mL-1, and 2.3%, respectively. The method proposed in this study was used to determine the content of remifentanil in pharmaceutical preparations.

Kohl is a traditional eye cosmetic used as eyeliner in different parts of Iran. They have different natural sources such as oils, nuts and leaves, and so on. They possess different physical and chemical properties and usually they have lead toxicity. The characterization of Kohl is evaluated as an important issue since it is directly affecting human health. So, in this study, kohl samples from various sources were characterized by different analytical methods such as scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX). Moreover, the sources of kohl samples were analyzed by three-dimensional (3-D) fluorescence spectroscopy. The fluorescence spectra of samples were evaluated by chemometrics methods to discriminate between different kohl sources. Principal component analyses (PCA) as unsupervised and extended canonical variates analysis (ECVA) as supervised classification methods were employed. PCA made relative discrimination between the various kohl samples and could only discriminate kohl stone from the others. Instead, more accurate classification results were achieved by ECVA and it represented sufficient ability for classification of all kohl samples. This study is the first study on Iranian-made kohl discrimination through 3-D fluorescence spectra and multivariate methods.

In this article, polycaprolactone (PCL) polymer nanofibers has been used in the presence of curcumin (Cur) to control the corrosion rate of temporary magnesium (alloy AZ31) implants. PCL, PCL-Cur, and sodium alginate (SA)-polyvinyl alcohol (PVA)/PCL-Cur polymer coating were produced. The mentioned nanofibers were produced using a simple and cost-effective electrospinning technique. We used different techniques to examine the properties of the produced fibers, and it was demonstrated that the hydrophobic produced nanofibers with contact angle of 135.2 degrees have continuous strands and a diameter of 171.57 nm. The presence of Cur inside PCL nanofiber not only did not have any effect on the PCL nanofiber morphology, but also it increased adhesion of the coating, and 74.59% of Cur was released after 7 days. To investigate the effects of different polymeric coatings on the surface of Mg metal in the simulated body fluid (SBF), SEM, weight measurement tests, pH measurement, Polarization, and Electrochemical Impedance Spectroscopy (EIS) has been used. During the study period there was no degradation in any part of the PCL-Cur hydrophobic polymer coating. For this coating, the percentage of weight loss, pH value, corrosion potential (Ecorr) and corrosion rate (CR) were 0.19%, 8.39, -1.388 V and 0.198 mm/y, respectively, where these values indicate the significant decrease of corrosion rate while using PCL-Cur coating.

Due to the inherent properties of electrochemical immunosensors, they are widely considered to ‎detect various biomarkers. This study developed an electrochemical immunosensor via the ‎excellent catalytic effect of nitrogen-doped graphene quantum dot supported by graphene ‎nanoribbon (N-GQD/GNR) composite as a sensing platform. ‎Nafion was used as‎ a ‎binder for ‏binding of‎ N-GQD/GNRon the electrode surface ‏‎. The modified electrode with N-GQD/GNR ‎composite was applied to develop the label-free electrochemical immunosensor for the ‎measurements of carbohydrate antigen 15-3 (CA15-3) biomarker. The catalytic activity of N-‎GQD/GNR nanocomposite increases the peak currents of the proposed immunosensor due to the ‎accelerated electron transfer between the sensing platform and probe. This immunosensor has a ‎wide linear range of 0.5 to 150.0 U mL-1, with a detection limit of 0.1 U mL-1. Also, the ‎proposed immunosensor has significant specificity, high sensitivity, and accuracy. The prepared ‎electrochemical immunosensor was used to detect CA15-3 protein in blood samples. ‎

In this work, an effective and simple method was utilized for the synthesis of zinc(II)-doped manganese ferrite magnetic nanoparticles (Zn0.2Mn0.8Fe2O4 MNPs). The prepared Zn0.2Mn0.8Fe2O4 MNPS was studied and characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction spectroscopy and Brunauer–Emmett–Teller analysis. The prepared Zn0.2Mn0.8Fe2O4 nanomaterial was applied as an applicable magnetic nano-sorbent for solid-phase extraction of cadmium(II) (Cd(II)) ions. The enriched Cd(II) ion was desorbed from the surface of the MNPs using a diluted HNO3 solution, and quantified by flame atomic absorption spectrometry. The influential variables, including the adsorbent mass, sample volume, pH, extraction time, and desorption conditions were investigated and optimized. Based on the method validation, the limit of detection for the developed method was 0.03 ng mL‒1 and the calibration curve is linear in the range of 0.1‒30.0 ng mL‒1. The method’s repeatability based on intra-day and inter-day precisions are 1.9% and 3.3%, respectively. For evaluation of the method accuracy, a certified reference material, natural waters, and industrial wastewater samples were analyzed.

Rare earth elements (REEs) are important materials in various technologies and have high economic value. Indonesia has the opportunity to become a country that has the potential to produce rare earth metal because it has tin mining areas where the by-product is monazite sand that contains 50% REEs. Based on this, a precise and efficient method is needed for separating REEs from the mixture. This study is a continuation of previous studies that selected parameters that affect the separation of REEs in the medium group from other groups by the precipitation method. This research optimizes the parameters of the selected precipitation method using the response surface method (Box-Behnken Design). The method used in this study was the optimization of the selective deposition method of REE hydroxide samples based on the different REEs pH for heavy, medium, and light groups using Box-Behnken Design. The parameters used were the reactant concentration, temperature, stirring speed, and pH. The result of parameter optimization that gave relevance to the maximum response rate of the REEs medium group was the oxalic acid concentration (1.0 N), precipitation temperature with oxalic acid (25°C), pH of heavy REEs precipitation (3.10), pH of the REEs medium group precipitation (7.30), and precipitation temperature (90°C). The separation efficiency of the REEs from monazite-origin samples treated to obtain the REEs hydroxide was 72.55%.