Analytical and Bioanalytical Chemistry Research
Volume:8 Issue: 2, Spring 2021

The corrosion inhibition capabilities of menthone which discovered in 2014 by our team have encouraged us to prepare again a new derivative of menthone called 7-isopropyl-4-methyl-4,5,6,7-tetrahydrobenzoisoxazole (MD). This compound was characterized by FT-IR, 1H NMR and 13C NMR techniques. Then, the evaluation of corrosion inhibition and adsorption behavior of MD onto carbon steel (CS) carried out in 1 M HCl using the weight loss (WL) analysis and electrochemical methods such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS). The inhibition efficiency (IE %) was increased by the increase of both the dose of MD (0.72 to 5.65 mM) and the temperature of the medium (298 to 323K). The thermodynamic kinetic parameters showed that the adsorption of MD on the carbon steel surface follows the Langmuir adsorption isotherm. Furthermore, PDP measurements exhibited that the studied MD inhibitor performs as a mixed-type inhibitor. Finally, the density functional theory (DFT), molecular electrostatic potential (MEPS) and Monte Carlo (MC) studies provide further insights about adsorption mechanism; indicating that the MD inhibitor can effectively limit corrosion onto the carbon steel surface. As a conclusion of this work, we have concluded that the synthesized MD can be used as an efficient inhibitor to stop carbon steel surface corrosion.

A microwave-assisted headspace solid-phase microextraction technique (MA-HS-SPME) with a periodic mesoporous organosilica based on alkylimidazolium ionic liquid (PMO-IL) was created and utilized as a greatly porous fiber covering substance effectively in investigating the Stachys lavandulifolia’s essential oil composition. The specimen was exposed to microwave radiation and its volatile constituents were gathered via the fiber from the specimen headspace and straightly inserted into a GC-MS addition port for investigation. A simplex technique was utilized for optimizing 3 various factors influencing the extraction effectiveness. Under the enhanced circumstances (indeed the sample weight of 2 g, extraction time of 2.0 min and microwave power of 300 W), the PMO-IL nanoporous fiber could proficiently adsorb volatile components of Stachys lavandulifolia. In optimum conditions, the repeatability for one fiber (n = 3), expressed as relative standard deviation (R.S.D.%), was between 3.5% and 12.1% for the test compounds. The suggested technique, relative to hydrodistillation (HD) can equally be used to monitor all the sample components easily, but it will require less sample quantity and duration. A few experiments based on the simplex method proved it to be fast while an efficient method that can be used to optimize micro-extraction conditions.

Determination of cetirizine, diltiazem, or verapamil and amlodipine in an active and in dosage formulations has been performed using a simple RP-HPLC method. Rosuvastatin is used in this novel RP-HPLC method as an internal standard to improve the selectivity of the method. At 230 nm, the separation was performed using a mobile phase consisting of methanol, acetonitrile, and water mixture in a ratio of 65:5:30, and pH at 2.8 allowed improved separation and faster times of analysis. ICH guidelines have pursued the validation of the method by assessing accuracy, precision (%RSD>2), and linearity (>0.999). The retention times of diltiazem, verapamil, amlodipine, cetirizine, and rosuvastatin was found to be 2.5, 3.2, 4.1, and 6 minutes, respectively. Method specificity was good as no interference of excipients of the tablets were observed in the analysis. The developed method could be used for routine quality control and in biological samples for the analysis of these drugs.

Essential oils (EO) represent an important source of bioactive molecules and are widely used for their great efficacy relating to their different therapeutic properties. Maire, an aromatic and native plant spontaneously growing in the North-Eastern regions of Algeria, by analyzing the chemical composition of its essential oil and evaluating the antioxidant and antimicrobial activities, together with the assay of the enzyme inhibitory effects against α-glucosidase and cholinesterase. Daucus virgatus EO was extracted by hydrodistillation and analyzed by gaschromatography-mass spectroscometry analysis (GC–MS). Twenty-one constituents accounting for 98% of the whole components were identified. β- pinene (77.9%) and α-pinene (7.6%) were the most abundant components. The antimicrobial activity against the pathogen microorganisms Listeria innocua, Salmonella typhimurium, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli and Candida albicans was investigated. The best antimicrobial effect was observed against S. typhimurium and C. albicans, which showed high sensitivity, with inhibition zones ranging between 27.3 and 25 mm; the minimum inhibitory concentrations were 15.63 and 31.25 μg ml-1, respectively. In the DPPH test, the essential oil showed a moderate antioxidant effect, with an IC50 value of 39.61 mg ml-1. D.virgatus EO exhibited an interesting inhibitory effect against α-glucosidase enzyme (IC50= 0.35 mg ml-1) compared with the positive control Acarbose (IC50= 0.24 mg ml-1), and a moderate inhibitory effect against cholinesterases enzymes, with IC50 values of 0.33 and 0.20 mg ml-1 for acetylcholinesterase and butyrylcholinesterase, respectively. D. virgatus EO might be used as a promising source of natural products with potential antimicrobial, antihyperglycemic and anti-Alzheimer effects.

An efficient method was developed for the synthesis of amino functionalized magnetic metal organic framework composite (Fe3O4-NH2@MOF-235) and the prepared composite was used as an adsorbent in magnetic solid-phase extraction (MSPE) for the separation and enrichment of Bisphenol A (BPA) from water samples followed by high performance liquid chromatography analysis. The prepared framework composite was characterized using transmission electron microscopy, x-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller and vibrating sample magnetometer techniques. Several parameters affecting the efficiency of magnetic separation including the amount of absorbent, extraction time, desorption solvent, and desorption volume were optimized. Under optimum conditions, the response of the method was linear over the concentration range of 0.1 to 20 ng ml-1 for studied BPA. The limit of detection of the method was 0.03 ng ml-1 at a signal-to-noise ratio of 3 with an RSD of lower than 6.5%. Finally, the proposed method was successfully applied for the determination of trace amounts of target analyte in mineral water samples.

A procedure, depending on the mutual derivatization and determination of thymol and Dapsone was developed and validated in this study. Dapsone was used as the derivatizing agent for the determination of thymol, and thymol was used as the derivatizing agent for the determination of Dapsone. An optimization study was performed for the derivatization reaction, i.e., the diazonium coupling reaction. Linear regression calibration plots for thymol and Dapsone in the direct reaction were constructed at 460 nm, within the concentration range of 0.3-7 μg.mL-1 for thymol and 0.3-4 μg.mL-1 for Dapsone, with limits of detection 0.086 and 0.053 μg.mL-1, respectively. Corresponding plots for the cloud point extraction of thymol and Dapsone were constructed at 460 nm, within the concentration range of 0.1-2 μg.mL-1 for thymol and 0.1-1.8 μg.mL-1 for Dapsone, with limits of detection 0.0445 and 0.023 μg.mL-1, respectively. Correlation coefficients and molar absorptivities, were improved using cloud point extraction. The proposed method can be applied for their trace detection in different matrices.

A Fast and centrifuge-less method called dispersive –restoration suspended droplet microextraction was developed for selective determination of trace amounts of Tl(III) by flame atomic absorption spectroscopy. In this method, 8-hydroxy quinoline was used as a complexing agent and toluene was used as an extracting solvent. The effective parameters for determination of Tl(III), such as, type of extraction solvent, dispersive time, resting time, magnetic stirrer speed and time, and pH were optimized. Under optimum conditions the calibration curve was found to be linear in the range of 8.0-1000 µg L-1 with R2 = 0.997. The percent of relative standard deviation (n=15), limit of detection and enrichment factor were 1.4%, 3.1 µg L-1 and 33, respectively. The method was successfully applied for determination of total thallium in real samples including water, nail and hair samples. The good recoveries in the range of 96-103% for real samples confirmed the accuracy and applicability of the present method

We successfully synthesized TMU-24 as metal-organic framework (MOF) and employed as an effective sorbent for preconcentration of the letrozole (LTZ) from biological samples. Using high-performance liquid chromatography with UV detector (HPLC-UV) coupling with solid-phase extraction (SPE) a sensitive, fast, and simple method for deteing of LTZ has been developed. The optimal conditions, such as pH, type of eluent solvents, contact time amount of adsorbent, and adsorption capacity were discussed. Under the optimized conditions, relative recoveries (RR) and preconcentration factor (PF) of the LTZ was obtained in the range of 92.4–99.6% and 33 respectively. Under the optimal conditions, LTZ can be determined with a limits of detection (LODs) 0.5 μg L-1 (based on S/N = 3), a linearity in the range of 1–250 μg L-1, and a reasonable linearity of 0.995. Also, the experimental adsorption isotherms models were investigated. The developed method was successfully used to the analysis of LTZ in urine samples.