Iranian Journal of Analytical Chemistry
Volume:6 Issue: 1, Winter and Spring 2019

In this study, hollow-fiber based liquid-phase microextraction method was developed of for selective extraction and/or preconcentration of triazine herbicides (atratone, desmetryn and atrazine) from locally brewed Ethiopian beverages prior to their separation and quantitative determination by high performance liquid chromatography with diode array detector. Parameters influencing extraction efficiency of the method including types of the extraction solvent, volume and pH of the sample solution, shaking speed, extraction time and salt concentration were investigated and optimum conditions were established. Under the optimal conditions limits of detections and quantifications were ranged from 0.02 – 0.04 and 0.05 – 0.12 µg/L, respectively. Calibration curves were linear over the range of 0.1 – 2 µg/L with coefficient of determinations of 0.990 or better. Intra- and inter-day precision studies, which were expressed as relative standard deviations were below 8 %. Satisfactory relative recoveries were also obtained for the target analytes, except for atrazine in Nech Tela and Filter Tela, which exhibited relatively lower recoveries. The results of the study indicated that the proposed method is an efficient alternative for selective extraction and/or preconcentration of residues of the target pesticides form Ethiopian locally brewed beverages as well as other similar sample matrices.

A rapid, powerful, satisfactory and modified signal-pre-processing method that is a hybrid of the wavelet transform with orthogonal signal correction (OSC) is used for pre-processing of spectrophotometric data of naphthalene, anthracene and pyrene as analytes after their preconcentration by salting-out assisted liquid–liquid extraction (SALLE) method. Water-miscible extraction solvent (1.0 mL of acetonitrile) and a suitable amount of salt (1.0 g of (NH4)2SO4) are added into the aqueous solution (4.0 mL) and dissolved using a vortex leading to the occurrence of phase separation. The target analytes in the sample was extracted into the water-miscible extraction solvent. After extraction, the absorbance of the analytes mixture was measured in the wavelength range of 200-400 nm. The wavelet orthogonal signal correction (WOSC) was established for denoising and reduction of spectrophotometric data and hybrid with partial least squares (PLS) regression method for simultaneous determination of the studied analytes after the SALLE procedure. The influence of various parameters, such as extraction solvent and volume, type and amount of salt, vortex time and sample pH were studied and optimized. The net analyte signal (NAS) method was used for calculating figures of merit. Linear range (LR) of calibration graphs for naphthalene, anthracene and pyrene were between 0.20 - 2.00, 0.10 - 1.50 and 0.07 -1.00 µg mL-1, respectively. The obtained model showed good prediction capability with root mean square error of prediction (RMSEP) of 0.030, 0.024 and 0.013 µg mL-1 for naphthalene, anthracene and pyrene, respectively. The simple WOSC-PLS method has been successfully applied for the simultaneous determination of these analytes in the spiked wastewater samples.

The study involves the adsorption of potentially toxic metals from brewery effluent (Beff), using size modified (UAD) and chemically modified (TAD) Borassus aethiopum biomass. Preliminary study and characterization of both brewery effluent and the derived adsorbents were recorded, with result showing some water quality parameters greater than threshold limits set by legislation. Both classical and instrumental techniques adopted for Sorbent characterization show valid outcome. Batch kinetic studies were monitored along with the role of varying conditions (Effluent concentration, pH, time and temperature) that could influence cadmium (Cd) and chromium (Cr) adsorption. Model applicability test supported the Pseudo second-order, with a high correlation coefficient, least error sum and high precision in qe. cal./exp. The mode of transport is best explained with intra-particle diffusion, not as the only rate limiting process. Generally, the chemically treated biomass exhibited metal removal efficiencies that could compete with the function of commercial activated carbon (CAC).

In this paper, magnetic nanoparticles functionalized by triazene ligand were prepared for extraction/preconcentration of trace amounts of mercury ions in water samples former on its determination with UV-Vis spectrophotometry. The modified magnetic nanoparticles were characterized by the various techniques such as Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and X –Ray Diffractometry (XRD). In the separation process, aqueous solution of Hg2+ ion was mixed with Fe3O4 magnetite nanoparticles modified with (E)-1-(2-Ethoxyphenyl)-3-(4-nitrophenyl)triaze-1-ene (ENT), (MNPs@SiO2-ENT) and then external magnetic field was applied for isolation of magnetite nanoparticles containing mercury ions. Experimental conditions for effective adsorption including pH, ENT amount, Fe3O4 NPs amounts, and eluent type have been studied and established. Under the optimal extraction and preconcentration conditions, calibration curve was linear in the range of 4–80 µgL-1 with r2 = 0.9992 (n=20), the limit of detection (LOD) 1.05µg L-1 and enrichment factor was 38, respectively. This technique was successfully used for the determination of Hg (II) in aqueous samples.

Food waste is one of the main issues for international organisms. It is not only an ethical and economic issue but it also depletes the environment of limited natural resources. Among strategies suitable for fighting such challenge, intelligent packaging is an interesting tool to reduce waste derived from households and retailers. Colorimetric detection of biogenic amines, well-known criterions of food corruption, shows the main role for monitoring of food safety. A novel colorimetric sensor based on hydrolysis-induced mercury metallization reaction to tune the localized surface plasmon resonance (LSPR) adsorption of Au nanoparticles sensitive to total volatile basic nitrogen (TVBN) released from meat has been created for real-time supervision of meat quality. Sensors were kept in atmosphere of ammonia simulating which changed its colour with changing of pH. This is the case of highly volatile amines, produced in food spoilage, specifically in the deterioration of meat, for which the color development of the smart labels can be used as a visual test for food freshness.

In this work, we synthesis and application of functionalized carbon nanotubes (CNTs) In this work, we synthesis and application of functionalized carbon nanotubes (CNTs) with6-amino-4-(3,4-dihydroxyphenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5 carbonitrile (pyrazole derivative (APC)) as sensing platform toward hydrazine (HZ). Electrochemical properties of functionalized carbon nanotubes composite (APC-CNT) were investigated by cyclic voltammetry, chronoamperometry and differential pulse voltammetry techniques. It was found that the APC-CNT composite exhibited a pair of redox peaks, which is due to the electron transfer between the APC and the glassy carbon electrode. The electrocatalytic properties of the APC-CNT composite for HZ oxidation was remarkably increased as compared to only CNTs. The kinetic parameters of the APC-CNT composite in the presence and absence of HZ was studied by electrochemical methods. The APC-CNT modified electrode revealed an excellent voltammetric response to oxidation of HZ with a wide linear range from 0.01 μM to 120.0 µM and limit of detection of 8.6 nM. Also, APC-CNT modified electrode shows high selectivity, good stability, reproducibility with a RSD less than 2.11%.

In the present study, the cysteamine electrochemical features were explored by La2O3/Co3O4 nanocomposite-modified screen printed electrode (La2O3/Co3O4/SPE) using voltammetry, chronoamperometry, and differential pulse voltammetry (DPV) techniques. The synthesized La2O3/Co3O4 nanocomposite qualities were considered by SEM, FT-IR, and XRD analyses. Exploiting the modified SPE electrode with La2O3/Co3O4 nanocomposite, the cysteamine electrooxidation kinetics was significantly enhanced by reducing the anodic over-potential. The constructed La2O3/Co3O4/SPE revealed voltammetric reactions of high sensitivity for cysteamine, resulting in a highly appropriate means of trace levels cysteamine measurement. The electrooxidation peak currents for cysteamine were found to change linearly in relation to its concentrations (1.0–700.0 μM) in detection limit of 0.3 μM. La2O3/Co3O4/SPE was utilized for the cysteamine quantification in real specimens.