[Show abstract][Hide abstract] ABSTRACT: Through a screening program for agrochemicals from Iranian medicinal plants, toxicity of the essential oils from Satureja hortensis L. and Teucrium polium L. (Lamiaceae) was evaluated against the two spotted spider mite, Tetranychus urticae Koch (Tetranychidae) adults, using leaf dipping and fumigant bioassays. The essential oils were extracted by a water steam distillation method with a Clevenger apparatus, and their chemical composition was studied by gas chromatography mass spectrometry (GC-MS). Oleic acid, thymol, palmitic acid and 1,8-cineole in the essential oil of S. hortensis and lycopersene, dodecane, decahydro-1,5-dimethyl-naphthalene and tridecane in the essential oil of T. polium were identified as main constituents. LC50 values were estimated as 0.876 and 1.784% in the leaf dipping assays and 7.074 and 5.395 μl/l air in the fumigant ones for S. hortensis and T. polium oils, respectively. Female adults of T. urticae were more susceptible to the essential oil of S. hortensis than T. polium in the dipping tests and to the essential oil of T. poliumthan and S. hortensis in the fumigant assays. These results indicated that S. hortensis and T. polium essential oils can be applied for the management of T. urticae to minimize damaging effects of the traditional synthetic acaricides.
Egyptian journal of pest control 06/2015; 25(1):171-176. · 0.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Highly ordered adsorbent mesoporous silica (MCM-41) was synthesised using a rapid method and its subsequent chemical modification with 3-mercaptopropyltrimethoxysilane (MPTMS) in toluene medium at 60°C was performed. The electro-reduction product of 4-nitrophenol (EP4NP), as a new kind of polyaminophenol-type chelating agent with a high affinity to Ni(II), was then incorporated into MPTMS-MCM-41. The resulting materials (MCM-41, MPTMS-MCM-41 and EP4NP-MPTMS-MCM-41) were characterised by scanning electron microscopy, powder X-ray diffraction, nitrogen gas sorption and Fourier transform-infrared spectrometry. The new modified adsorbent EP4NP-MPTMS-MCM-41 was then employed for preconcentration of ultra-trace amounts of Ni(II) by dispersive micro solid phase extraction prior to inductively coupled plasma-optical emission spectrometry. The effects of variables such as pH, mass of the chelating agent, the amount of EP4NP-MPTMS-MCM-41, stirring time of extraction step, HCl concentration and stirring time during elution were optimised and the calibration curve was plotted. The limits of detection and quantitation were 0.006 and 0.019 μg L−1, respectively. The mean, standard error and relative standard deviation for five replicates of 0.5 μg L−1 Ni(II) were calculated to be 0.48 μg L−1, 4.0% and 3.2%, respectively. The proposed method was successfully applied for determination of Ni(II) in wastewater samples.
International Journal of Environmental Analytical Chemistry 05/2015; 95(6):1-14. DOI:10.1080/03067319.2015.1046053 · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper a simple, selective, sensitive and reproducible stripping method based on adsorption of Se(IV) in the form of 5-nitropiazoselenol complex at the surface of in situ plated bismuth film electrode was introduced. All affecting parameters on adsorption, stripping and complex formation steps were evaluated and studied. Under optimum conditions the established calibration curve obeyed linear regression equation in the range of 2 to 50 µg/L of Se(IV) concentrations. The estimated detection and quantification limit were 0.05 and 0.15 µg/L of Se(IV), respectively. In addition, the mean and RSD for determination of 5 µg/L of Se(IV) were calculated to be 4.91 and 2.8% (n=5). The accuracy of method was certified by comparison of the results obtained from the proposed method and those obtained from ICP-OES as reference method.
[Show abstract][Hide abstract] ABSTRACT: Self-accumulation of Se(IV) on a new Bi/Hg film-coated electrode has been investigated by adsorptive cathodic stripping voltammetry. The parameters influencing the voltammetric response were evaluated and optimized in an open circuit system. The high adsorption tendency of Se(IV) on a Bi/Hg film-coated electrode has been addressed. The limits of detection and quantification under optimum conditions were 0.07 and 0.25 ng mL−1, respectively, which are comparable with those of some other methods used for the determination of Se(IV). The mean, standard error and RSD for five replications of 5 ng mL−1 of Se(IV) were calculated to be 4.94, 0.12 and 2.4%, respectively. This novel procedure was applied for the determination of selenium in vegetable, fruits and water samples. The results obtained through the proposed method were in good agreement with those of inductively coupled plasma-optical emission spectrometry (ICP-OES).
[Show abstract][Hide abstract] ABSTRACT: Utilization of synthetic acaricides causes negative side-effects on nontarget organisms and environment and most of themite species such as two spotted spidermite, Tetranychus urticae Koch, are becoming resistant to these chemicals. In the present study, essential oils of fennel, Foeniculum vulgareMill., and lavender, Lavandula angustifoliaMiller, were hydrodistilled using Clevenger apparatus and chemical composition of these oils was analyzed by GC-MS. Anethole (46.73%), limonene (13.65%), and 𝛼-fenchone (8.27%) in the fennel essential oil and linalool (28.63%), 1,8-cineole (18.65%), and 1-borneol (15.94%) in the lavender essential oil were found as main components. Contact and fumigant toxicity of essential oils was assessed against adult females of T. urticae after 24 h exposure time.The essential oils revealed strong toxicity in both contact and fumigant bioassays and the activity dependeds on essential oil
concentrations. Lethal concentration 50% for the population of mite (LC50) was found as 0.557% (0.445–0.716) and 0.792% (0.598–1.091) in the contact toxicity and 1.876 𝜇L/L air (1.786–1.982) and 1.971 𝜇L/L air (1.628–2.478) in the fumigant toxicity for fennel and lavender oils, respectively. Results indicated that F. vulgare and L. angustifolia essential oils might be useful for managing of two spotted spider mite, T. urticae.
Psyche A Journal of Entomology 12/2014; 2014:6. DOI:10.1155/2014/424078
[Show abstract][Hide abstract] ABSTRACT: This investigation involved electrochemical synthesis of a new Ni(II) selective chelating agent by electropolymerization of 4-nitrophenol in acetate medium. The prepared polymer was characterized by FT-IR, 1H-NMR, CHNO elemental analysis, GPC, and UV-Vis spectrometry and a suitable chemical structure was suggested. This new ligand was successfully applied in cloud point extraction (CPE) of Ni(II) before flame atomic absorption spectrometry (FAAS) measurements. The pH and the concentration of the phosphate buffer, chelating agent, surfactant and salt were optimized. In the presence of foreign ions, no significant interferences were observed. Under optimum conditions, the limits of detection (LOD) and quantification (LOQ) were 0.76 and 2.53 ng mL−1, respectively. The mean, preconcentration factor, standard error and RSD for five replicates of 10 ng mL−1 Ni(II) were calculated to be 9.78 ng mL−1, 29.3, 2.2% and 3.36%, respectively. The method presented good sensitivity and selectivity and was applied for the determination of trace amounts of Ni(II) in various water and wastewater samples. The results obtained by the proposed method were in good agreement with the results of inductively coupled plasma-optical emission spectrometry (ICP-OES).
[Show abstract][Hide abstract] ABSTRACT: The major constituents of the oil of Lavandula angustifolia Mill were estimated as borneoll (8.57%), alpha terpinene (6.22%), linolool (4.91%) geranyl proprionate (3.76%), butanoic acid hexyl ester (2.99%) and caryophyllene oxide (2.72%). LC10, LC30 and LC50 were estimated as 0.31%, 0.705% and 1.24% respectively. The sublethal concentration (LC30) of essential oil affected the nutritional indices of 4th instar larvae of Glyphodes pyloalis. The essential oil reduced total protein, carbohydrate and lipid when compared with the control. All concentrations (0.25%, 0.5%, 1%, and 2%) of essential oil affected the major macromolecules and activities of key enzyme in G. pyloalis.
[Show abstract][Hide abstract] ABSTRACT: A pencil graphite electrode coated by copper (II)–carmoisine dye complex in polyaniline (emeraldine base form) matrix (termed
as PGE/PA/Cu-Car) was prepared and used as copper ion-selective electrode. The introduced electrode was found to have high
selectivity toward copper ion (II) and exhibited wide working concentration range, low response time, and good shelf life.
The sensor electrode showed a linear Nernstian response over the range of 5.0 × 10−6 to 1.0 × 10−1 M with a slope of 29.7 ± 1 mV per decade change in concentration. A detection limit of 2.0 × 10−6 M was obtained. The optimum pH working range of the electrode was found to be 4.0–7.0.
Journal of Solid State Electrochemistry 03/2012; 16(3). DOI:10.1007/s10008-011-1436-2 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The high tendency of 5-nitropiazselenol for self-accumulation on thin mercury film electrode was used innovatively for determination of Se(IV) in natural waters. 5-Nitropiazselenol was formed by reaction between Se(IV) and 4-nitro-1,2-phenylenediamine in acidic solution and self-accumulation process was carried out directly from reaction media. The adsorbed 5-nitropiazselenol was stripped in HCl solution by DP cathodic potential scan. All parameters influencing the measurement were optimized and evaluated. Detection limit of this method is 0.06 ng mL(-1). Interferences of various cations and anions were studied. The adsorption tendency of some other piazselenols made by some aromatic ortho-diamines was also investigated. The problems arising from applying potential during accumulation process in natural waters analysis were discussed. This method was applied for determination of Se(IV) in natural waters collected from some internationally registrated lagoons south of Caspian Sea. The obtained results were compared with the results of ICP-AES and DPCSV after electrochemical preconcentration.
[Show abstract][Hide abstract] ABSTRACT: In this work bovine albumin was used innovatively as a medium for adsorptive accumulation of Se-I(2) on thin mercury film electrode. Se-I(2) was formed by reaction between Se(IV) and iodide in HCl media. The adsorbed Se-I(2) was stripped in 0.05 M HCl by differential pulse cathodic potential scan. The proposed method was successfully applied to analysis of Se(IV) and Se(VI) in natural waters sampled from some lagoons south of Caspian Sea. The optimum reaction conditions and other analytical parameters and influence of cations and anions were studied. The detection limit was 0.37 ng mL(-1). The obtained results were compared with the results of DPCSV after electrochemical preconcentration, HG-AAS and ICP-AES.
[Show abstract][Hide abstract] ABSTRACT: The chemical composition of worm wood Artemisia annua L. (Astraceae), a medicinal plant, was studied by gas chromatography and gas chromatography- mass spectrometry (GC-MS). About 60 compounds were identified, from which the major compounds were erythritol (50.30%), camphore (7.25%), pinocarveol (4.13%) and diethoxyethane (2.18%). The effect of crude extract on deterrency was maximal in 1000 μL/L treatment (only 4.66 ±1.05 insects were attracted to treated food) compared to control (12.6 ±0.96) The growth regulatory effect showed that 1600 μL/L treatment variously affected the weight of larvae, pupae and adult (0.48 ±0.003, 2.17 ±0.02 and 1.31 ±0.015, respectively) and finally the ovicidal effect and the number of adults appearing in F1 were similarly affected (38.5 ±1.7 and 33.75 ±2.31), comparing to control (99.25 ±1.727 and 92.5 ±1.35). The present result and previous results on this plant species indicate that it can be a good candidate for controlling stored product insects.