Analytical and Bioanalytical Chemistry Research
Volume:7 Issue: 2, Spring 2020

Hydrazine has been identified as a carcinogenic mutagenic, hepatotoxic, and neurotoxin material. A metal-organic framework with tetragonal symmetry, DMOF-1 (Zn2(bdc)2dabco) was synthesized by a versatile and facile technique, followed by its efficient development and validation as hydrazine electrochemical sensor. Differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) techniques were used as diagnostic techniques. In this study, scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to characterize the MOF. In the electro-oxidation of hydrazine, there was a highly catalytic activity shown by the modified electrode. In addition, there was a greater signal response, compared to the unmodified electrode, which was primarily because DMOF-1 offered the establishment of large active surface area. Also, the detection limit for hydrazine, linear range, and sensor sensitivity were reported to be 0.02 µM, 0.09-400.0 µM, and 0.0863 µA/µM-1, respectively. Ultimately, the amplified sensor was able to properly analyze hydrazine in different samples of water.

The use MOF-508a as sensing component for the precise discerning of bisphenol A via the electrochemical technique and its synthesis by a simple method were reported in the present study. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were applied to describe the MOF-508a’s composition and structure. In addition, MOF-508a was exploited so that the glassy carbon electrode could be altered for the bisphenol A’s electrochemical oxidation. The results were indicative of illustration of palpable oxidation peak with lowering over-potential by the designed MOF-508a /GCE. In addition, there was a greater signal response, compared to the unmodified electrode, which was primarily because MOF-508a offered the establishment of large active surface area. As such, this process led to a considerable improvement in the electrochemical surface area. Moreover, adding the elevating bisphenol A concentration resulted in a severe elevation in the anodic peak, presented by the measurements of differential pulse voltammetry (DPV). Furthermore, excellent sensitivity (0.0564 µA.µM-1) with low limit of detection (0.03 µM), a wide linear range (0.1–700.0µM), and high selectivity were shown by the analytical performance of the modified electrode.

Poly-dopamine, inspired by biopolymers of mussels, is an adhesive catecholamine possessing low cytotoxicity and very good biocompatibility. In the present study, poly-dopamine nanoparticles (PDNP), as a biopolymer, were synthesized and characterized using FTIR spectroscopy, scanning electron microscopy and electrochemical methods. The drop casted PDNPs at the surface of carbon paste electrode (CPE) shows a great tendency to form complexes with Cu(II). This fact was selected for determination of Cu(II) in water. Copper exists broadly in various oxidation states in nature. It is also as one of the most harmful pollutants in the environment due to its non-degradability, high toxicity and bioaccumulation and so determination of it is demanded. X-ray photoelectron spectroscopy (XPS) was applied to clarify the interaction. The influential parameters affecting Cu(II) binding were optimized including adsorption time, pH, and stirring speed. In optimum condition, differential pulse voltammetry was exploited for analytical determination of Cu(II) in the ranges of 1.0 100 µM and 0.05 1.0 µM with the limit of detection 0.04 µM. The sensor ability for Copper determination in water samples was demonstrated.

This study aimed to introduce a new method based on Hollow Fiber in order to determination of acetic anhydride (AA) in the air. Hydroxylamine hydrochloride and sodium hydroxide (1:1), were used as extraction solvent. This method was studied in the laboratory under various conditions. In order to make different concentrations of AA in the air, a standard glass chamber was used. The optimization of the sampling parameters and breakthrough volume was performed using the response surface method (RSM) and Design-Expert software (v.11.0). The results of the study indicated that the optimum sampling rate was 10 mL/min. The repeatability estimates of the proposed method including intra and inter-day were in the confine of 0.079–0.11 and 0.081–0.14, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) of the examined analytes were 0.003 and 0.009 ng/mL, respectively. The storage time for the HF sampling method was seven days at laboratory temperature. The overall conclusion is that the HF sampling method showed a great sensitivity for the sampling of AA in the air. It could be assumed that HF sampling method is a fast, reliable and sensitive method and had a proper performance in the sampling of AA, compared to the National Institute for Occupational Safety and Health (NIOSH)- 3506 method.

The objective of this study is to report the comparative chemical analysis of essential oil (EO) obtained by hydrodistillation (HD) and volatile fraction (VF) detected by headspace solid phase micro-extraction (HS–SPME) isolated from Pulicaria mauritanica using Gas Chromatography–Retention Indices (GC-RI) and GC–Mass Spectrometry (GC-MS) and to evaluate in vitro the antimicrobial activity of P. mauritanica EO against three bacterial strains referenced by the ATCC (American Type Culture Collection): Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Pseudomonas aeruginosa (ATCC 27853) and a one yeast Candida albicans using the paper disc diffusion and minimum inhibitory concentration (MIC) assays. The chromatographic profile indicates that quantitative and semi qualitative differences between the chemical compositions of both analysed samples were observed. The antimicrobial activity tested by two methods indicates that this EO was more effective against three strains tested excepted P. aeruginosa which was most resistant. Indeed, the results of the report MBC (Minimum Bactericidal Concentration)/MIC show that the EO has a bactericidal effect on S. aureus and a bacteriostatic and fungistatic effect on E. coli and C. albicans, respectively. P. mauritanica EO seems be a promising source of natural products with potential antimicrobial activity.

Herein, a convenient, simple, rapid, labor efficient and economical salt-induced homogeneous liquid-liquid microextraction technique coupled with high-performance liquid chromatography-photo diode array detection system was developed for sample preparation, extraction and quantitative determination of diazinon and cypermethrin in milk samples. In a single step, a homogeneous solution containing acetone and dichloromethane was used for the extraction of analytes and precipitation of milk proteins. This solution was broken by the addition of sodium chloride as phase separator agent. Several variables that influence the extraction efficiency such as composition of homogeneous solution, concentration of phase separator agent and extraction time were fully evaluated and optimized. Under optimal conditions for analysis of two pesticides, matrix-matched calibration curves with dynamic linear ranges of 0.065-1300 µg L-1, limit of detection of 0.018-0.03 µg L-1, and the limit of quantification of 0.065-0.1 µg L-1 were obtained. The enrichment factors and extraction recoveries were 158-174 and 79-87%, respectively. Precision and accuracy of the method based on RSDs and REs for three concentration levels of both pesticides were achieved between 2.7-12.3% and 6.1-8.3% (n=5), respectively. The represented method was successfully applied for the simultaneous assay of diazinon and cypermethrin in different milk samples.

The acute toxicity in water of a series of drugs, including antibiotics, antihistamines, antifungals, steroidal and non-steroidal anti-inflammatories, was evaluated through the measurement of bioluminescence from the bacterium Vibrio fischeri. The drugs were spiked in water at concentration in the range 1.0-50.0 g/mL, distributed over six concentration levels, and their toxicity evaluated in terms of response rate calculated along 30 min of incubation. The test was also applied to real river samples previously assayed by HPLC method. The parameters LOEC (lowest observable effect concentration) and EC50 (half effective concentration) were calculated. Chlortetracycline, promethazine, betamethasone, ketoconazole and econazole were found to be very toxic. Diclofenac and ketoprofen showed toxicity only at the highest concentrations tested. Clindamycin, neomycin and oxatomide induced a decrease in bioluminescence but below the toxicity limits. In contrast, erythromycin and diphenhydramine showed an increase of bioluminescence, known as hormesis. The toxicity was amplified in samples containing drug mixtures, demonstrating additive or synergistic activity.

In this study, solvent extraction technique combined with response surface methodology (RSM) applying Box-Behnken design was applied to study the uptake of metal ions from aqueous solutions using H2BMPDE. The extractions were monitored based on the process variables of time, temperature and concentration of hydrochloric acid, metal ions and H2BMPDE. The metal ions binding properties of H2BMPDE optimized using RSM models for all the metal ions indicated estimated extraction percentage of ˃99%. The predicted and experimental values under the same conditions, showed less than 5% difference thereby making the Box- Behnken design approach an efficient, effective and reliable method for the uptake of metal ions from aqueous solution with H2BMPDE by solvent extraction technique. The novel Schiff base (H2BMPDE) synthesized was characterized using common physicochemical techniques of UV-vis, FT-IR, elemental analysis, GC-MS and NMR spectral data. The result obtained indicated that the process could be applied in the removal of metal ions from environmental samples such as soil, industrial waste water and acid mine sites.

Silicagel-MnO2 (Si-MnO2) nanocomposite was prepared by co-precipitation method, and characterized using SEM, XPS and FT-IR techniques. Afterwards, adsorption behavior of malachite green (MG) dye onto prepared Si-MnO2 has been examined and optimized. Batch procedure has been used for sorption kinetic and equilibrium examinations. The experiments have been done with an initial concentration of 100 mg.L-1 at room temperature. The representation of the equilibrium data is fully assessed via Freundlich and Langmuir isotherms. With regard to Langmuir model, the greatest adsorption capacity of MG dye onto Si-MnO2 was found to be 107.5 mg.g-1, at room temperature. Kinetic examinations revealed that adsorption procedure follows pseudo-first-order model. Based on the results, prepared Si-MnO2 may be economically and efficiently used as an adsorbent to remove MG dye from wastewater samples. Desorption of the dye has been done using HCl 0.1 mol.L–1 solution and regenerated Si-MnO2 can be used for five cycles of MG dye adsorption.

MIL-53(Fe) with huge porosity has been synthesized by microwave radiation in the different ‎conditions: various powers (80, 100W) and time (5, 10 min). Nano-sized crystals were ‎characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier ‎transform infrared spectroscopy (FTIR) and specific surface area analysis. After performing the characterization, MIL-53(Fe)-1 with the best porous structure for Pb (II) and Cd (II)‎ removal was used for all tests from aqueous solution. The best condition for synthesis was 5 min and 80 W. Then the best porous structure was selected for removal of Pb (II) / Cd (II) from aqueous solution. The ‎response surface methodology (RSM) based on central composite design (CCD) was applied to ‎optimize the removal capacity. In these experimental designs, four independent variables were studied and the best condition was evaluated as ‎‎pH(in the range of 6-8), temperature (40-50◦C), contact time (50 min), and adsorbent amount (0.1-0.3 g.L-1). The removal efficiency and ‎capacity of MIL-53(Fe) for Pb (II) and Cd (II) was further surveyed. Langmuir equation was the ‎best isotherm to describe the adsorption manner of Pb (II) and Cd (II) ions (qmax values ( 178.57 and 714.28 mg g−1) for Pb (II) and Cd (II)). The adsorption ‎process was confirmed by a pseudo-second-order kinetic pattern. The result of thermodynamic ‎studies displayed that the sorption process was spontaneous and exothermal.