Chemical composition of the essential oils of Citrus sinensis cv. valencia and a quantitative structure-retention relationship study for the prediction of retention indices by multiple linear regression

The chemical composition of the volatile fraction obtained by head-space solid phase microextraction (HS-SPME), single drop microextraction (SDME) and the essential oil obtained by cold-press from the peels of C. sinensis cv. valencia were analyzed employing gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The main components were limonene (61.34 %, 68.27 %, 90.50 %), myrcene (17.55 %, 12.35 %, 2.50 %), sabinene (6.50 %, 7.62 %, 0.5 %) and α-pinene (0 %, 6.65 %, 1.4 %) respectively obtained by HS-SPME, SDME and cold-press. Then a quantitative structure-retention relationship (QSRR) study for the prediction of retention indices (RI) of the compounds was developed by application of structural descriptors and the multiple linear regression (MLR) method. Principal components analysis was used to select the training set. A simple model with low standard errors and high correlation coefficients was obtained. The results illustrated that linear techniques such as MLR combined with a successful variable selection procedure are capable of generating an efficient QSRR model for prediction of the retention indices of different compounds. This model, with high statistical significance (R2 train = 0.983, R2 test = 0.970, Q2 LOO = 0.962, Q2 LGO = 0.936, REP(%) = 3.00), could be used adequately for the prediction and description of the retention indices of the volatile compounds

Chemical composition of the essential oils of Citrus sinensis cv. Valencia and a quantitative structure-retention relationship study for the prediction of retention indices by multiple linear regression

Abstract: The chemical composition of the volatile fraction obtained by headspace solid phase microextraction (HS-SPME), single drop microextraction (SDME) and the essential oil obtained by cold-press from the peels of C. sinensis cv. Valencia were analyzed employing gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC--MS). The main components were limonene (61.34, 68.27 and 90.50 %), myrcene (17.55, 12.35 and 2.50 %), sabinene (6.50, 7.62 and 0.5 %) and α-pinene (0, 6.65 and 1.4 %) respectively obtained by HS-SPME, SDME and cold--press. Then a quantitative structure-retention relationship (QSRR) study for the prediction of retention indices (RI) of the compounds was developed by application of structural descriptors and the multiple linear regression (MLR) method. Principal components analysis was used to select the training set. A simple model with low standard errors and high correlation coefficients was obtained. The results illustrated that linear techniques such as MLR combined with a successful variable selection procedure are capable of generating an efficient QSRR model for prediction of the retention indices of different compounds. This model, with high statistical significance (R 2 train = 0.983, R 2 test = = 0.970, Q 2 LOO = 0.962, Q 2 LGO = 0.936, REP(%) = 3.00), could be used adequately for the prediction and description of the retention indices of the volatile compounds

Preparation of Ionic Liquid-Silica Nanoparticles Nanocomposite Film Coated Porous Copper Wire for SolidPhase Microextraction of Pesticides from Tomato Samples

In this study, a new solid phase micro extraction (SPME)fiber coated by sol-gel technology based on polyethyleneglycol (PEG) grafted ionic liquids (ILs), and silicananoparticles (silica NPs) on a porous copper substratewas fabricated. The as-prepared fiber (PEG-ILs-silicaNPs) was then used to extract a variety of pesticides intomato samples before prior to their gas chromatographyflame ionization detection (GC-FID). The key parametersinfluencing extraction efficiency containing includingextraction time, stirring rate, extraction temperature, pH,ionic strength, and desorption temperature, and time wereinvestigated and optimized. The relative standarddeviations (RSDs) for single fiber repeatability rangedfrom 1.2 to 4.6% (n=6), and the RSDs for fiber-to-fiberreproducibility (n=6) were 3.3–6.8%, respectively. Theproposed method based on the PEG-ILs-silica NPs fiberwas successfully applied for the determination of targetedpesticides in tomato samples with good recoveries from89.8 to 103.5% (RSDs=2.1-6.9)

A novel electrochemical sensor based on Co3O4-CeO2-ZnO multi metal oxide nanocomposite for simultaneous detection of nanomolar Pb2+ and Hg2+ in different kind of spices

Simultaneous and individual determination of Pb2+ and Hg2+ ions were carried out based on the synergistic effect of Co3O4, CeO2 and ZnO nanoparticles into the carbon paste electrode. The morphology of synthesized nanocomposite (Co3O4-CeO2-ZnO) was investigated by Scanning Electron Microscope, Transmission Electron Microscope, X-ray diffraction and Fourier Transform Infrared spectroscopy. The voltammetric current has increased linearly by increasing the concentration of Pb2+ and Hg2+ ions. The linear ranges of the Co3O4-CeO2-ZnO/CPE sensor were obtained 0.27-18.42 (for Pb2+ ions) and 0.42-31.30 nM (for Hg2+ ions), under optimum condition. The detection limits (3Sb/m) were obtained 0.054 nM for Pb2+ and 0.097 nM for Hg2+, respectively. The proposed electrochemical sensor acts as a sensitive and selective method for simultaneous determination of two heavy metal ions and shows excellent repeatability, reproducibility, and stability, with relative standard deviation (RSD) less than 3%. Finally, Co3O4-CeO2-ZnO/CPE was successfully applied for the determination of Pb2+ and Hg2+ in different kind of spices

Study the absorption process of cadmium ions by Fe3O4/L-methionine/graphene oxide and graphene Aerogel nanocomposites from aqueous environments

In this research, the synthesis of L/Fe3O4-methionine and graphene oxide and graphene aerogel nanocomposites (Fe3O4/L-Met/GO, Fe3O4/L-Met, Fe3O4/L-Met/GA) was carried out. Then the structure of the synthesized nanocomposites was confirmed by FT-IR, FE-SEM and BET analyses. Then, the effect of different experimental parameters such as initial pH and contact time on the process of cadmium surface adsorption were investigated. The results showed that the highest percentage of cadmium absorption (90%) occurred at Ph=6 by Fe3O4/L-Met/GA nano adsorbent. Therefore, the cadmium (Cd2+) absorption capacity by Fe3O4/L-Met/GA nanocomposite (212.31 mg/g) is higher than the cadmium (Cd2+) absorption capacity by Fe3O4/L-Met nanocomposites (201.23 mg/g). ) Obtained. Adsorption kinetics data showed excellent fit with pseudo-second-order models (R2>0.99) and Freundlich isotherm models.showed high adsorption capacity towards Cd2+ (212.31 mg/g), which was significantly higher than Fe3O4/L-Met (201.23 mg/g). Finally, adsorption kinetics, isotherm studies were investigated. Absorption data showed excellent fit with quasi-second order models (R2> 0.99) and Freundlich isotherm models

5,5′-Dimeth­oxy-2,2′-[4,5-dimethyl-o-phenyl­enebis(nitrilo­methyl­idyne)]diphenol

In the crystal structure of the title compound, C24H24N2O4, the dihedral angles between the central and the two outer benzene rings are 48.12 (8) and 21.44 (8)°. Intra­molecular O—H⋯N hydrogen bonding generates S(6) rings

Determination of Residual Nonsteroidal Anti-Inflammatory Drugs in Aqueous Sample Using Magnetic Nanoparticles Modified with Cetyltrimethylammonium Bromide by High Performance Liquid Chromatography

A simple and sensitive solid-phase extraction method for separation and preconcentration of trace amount of four nonsteroidal anti-inflammatory drugs (naproxen, indomethacin, diclofenac, and ibuprofen) using Fe3O4 magnetic nanoparticles modified with cetyltrimethylammonium bromide has been developed. For this purpose, the surface of MNPs was modified with cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. Effects of different parameters influencing the extraction efficiency of drugs including the pH, amount of salt, shaking time, eluent type, the volume of solvent, amount of adsorbent, sample volume, and the time of desorption were investigated and optimized. Methanol has been used as desorption solvent and the extracts were analysed on a reversed-phase octadecyl silica column using 0.02 M phosphate-buffer (pH = 6.02) acetonitrile (65 : 35 v/v) as the mobile phase and the effluents were measured at 202 nm with ultraviolet detector. The relative standard deviation (RSD%) of the method was investigated at three concentrations (25, 50, and 200 ng/mL) and was in the range of 3.98–9.83% (n=6) for 50 ng/mL. The calibration curves obtained for studied drugs show reasonable linearity (R2>0.99) and the limit of detection (LODs) ranged between 2 and 7 ng/mL. Finally, the proposed method has been effectively employed in extraction and determination of the drugs in biological and environmental samples

A comprehensive study on removal of cadmium from aqueous solution by using mesoporous SBA-15 functionalized by 1,5-diphenyl carbazide: experimental design, kinetic, thermodynamic, and isotherm aspects

In this study, a new adsorbent, which was synthesized by using SBA-15Santa Barbara Amorphous. modified with 1,5-diphenyl carbazide, was employed to extract cadmium (Cd) from aquatic systems. First, the sorbent was identified via various characterization techniques, and then the response surface methodology approach was applied for modeling and optimizing the adsorption performance of the sorbent. Under optimum conditions ($\mathrm{pH}=5.75$, an adsorbent dose of 4.55 mg, and a Cd concentration of 25.39 mg/L), an adsorption capacity of 160 mg/g was obtained. In addition, the sorption process was fast; it attained equilibrium in 25.39 min. Furthermore, the sorbent regenerated by nitric acid was reused without any significant loss of adsorption capacity. Finally, the experimental data were studied by different isotherm models and well described by the Langmuir model

A comprehensive study on removal of cadmium from aqueous solution by using mesoporous SBA-15 functionalized by 1,5-diphenyl carbazide: experimental design, kinetic, thermodynamic, and isotherm aspects

In this study, a new adsorbent, which was synthesized by using SBA-15Santa Barbara Amorphous. modified with 1,5-diphenyl carbazide, was employed to extract cadmium (Cd) from aquatic systems. First, the sorbent was identified via various characterization techniques, and then the response surface methodology approach was applied for modeling and optimizing the adsorption performance of the sorbent. Under optimum conditions ($\mathrm{pH}=5.75$, an adsorbent dose of 4.55 mg, and a Cd concentration of 25.39 mg/L), an adsorption capacity of 160 mg/g was obtained. In addition, the sorption process was fast; it attained equilibrium in 25.39 min. Furthermore, the sorbent regenerated by nitric acid was reused without any significant loss of adsorption capacity. Finally, the experimental data were studied by different isotherm models and well described by the Langmuir model

Essential oil composition and in vitro antibacterial activity of Chenopodium album subsp. striatum

The objective of this study was to identify the bioactive compounds of essential oil and evaluate the antibacterial activity of the essential oil extracted from Chenopodium album subsp. striatum against multidrug-resistant bacterial strains (MDR) which were isolated from clinical specimens by conventional methods. Furthermore, eight different Gram-negative and Gram-positive multidrug-resistant bacterial strains were used to investigate the antibacterial potential of the essential oil. The antibacterial activity was tested using MIC and MBC microdilution method, well and disc diffusion in different concentration. The hydro-distillation of aerial parts powder yield was 0.466% (v/w). Essential oil showed bactericidal activity against both MDR Gram-negative and Gram-positive bacterial strains. MIC and MBC results were ranged from 0.31 to 2.5 and 0.62 to 5.0 mg/mL. The inhibition zones in well-diffusion method were ranged from 7 ± 0.6 mm to 15 ± 1.0 mm. Disc diffusion method was ranged from 7 ± 0.0 mm to 16 ± 0.6 mm depending on the type of bacteria strain and essential oil concentration. Essential oil of Ch. album had the greatest potential to be considered as an antibacterial agent against MDR bacteria strain. This potential was due to different biological and bioactive compounds like phytol, linalool, α-terpineol and linolenic acid in the plant