Acetonitrile’s Effect on the Efficiency of Ethanol Electrooxidation at a Polycrystalline Pt Electrode in Relation to pH-Dependent Fuel Cell Applications

The present paper reports cyclic voltammetric and a.c. impedance spectroscopy investigations on the influence of the acetonitrile concentration on the kinetics (and individual product’s efficiency) of the ethanol oxidation reaction (EOR), performed on a polycrystalline Pt electrode surface in 0.5 M H2SO4 and 0.1 M NaOH supporting solutions. The kinetics of the EOR were examined at room temperature over the voltammetric potential range, which covers the electrooxidation of surface-adsorbed COAds species, as well as the formation of acetaldehyde molecules. In addition, the time-dependent efficiency of acetate and acetaldehyde formation in relation to the initial acetonitrile content for both acidic and alkaline electrolytes was evaluated by means of spectrophotometric Ultraviolet/ Visible Spectroscopy (UV-VIS) instrumental analysis.

Stability and Mobility of Lid Lipmnk in Acetonitrile by Molecular Dynamics Simulations Approach

Manuk lipase (lipMNK) from the thermophilic bacterium Geobacillus sp is a double lid lipase containing short and long lid segments. A few studies demonstrated that catalytic action of lipase involved the movement of lid segments from closed to open conformation upon the substrate binding. One factor that affects conformational dynamics of the lid segments is solvent polarity. The presence of acetonitrile in certain concentration has showed to enhance lipase activity. In this study, the effect of acetonitrile to the stability and activity of lipMNK was studied at the atomic level by molecular dynamics (MD) simulation. MD was carried out by NPT ensemble at 358 K for 100 nano seconds in various ratio of acetonitrile:water solvent mixtures. The results showed that the conformation of lipMNK was stable up to 70%. However, the effect of lid movement was significantly observed since the concentration at 20% acetonitrile. Detailed molecular analysis at this acetonitrile concentration revealed that the two lids moved in different modes upon opening and closing movement. In the opening movement, the two lids appeared to move in almost simultaneously, while during the closing movement, it was observed sequentially, started by short segment followed by long segment lid.

The Role of the Additive in the Form of Na2SO4 in the Epoxidation of Dialllyl Ether

This work presents the research on the influence of the addition of the appropriate amounts of the inorganic salt (Na2SO4) on the reduction of the ineffective decomposition of hydrogen peroxide (H2O2) and simultaneously on the increase of the efficiency of hydrogen peroxide conversion. The studies were carried out for the epoxidation of diallyl ether to allyl-glycidyl ether with 30 wt% hydrogen peroxide on the TS-1 catalyst and in the presence of acetonitrile as the solvent. The studies were conducted in the following conditions: the temperature of 70°C, the molar ratio of diallyl ether/hydrogen peroxide = 3:1, the acetonitrile concentration of 50 wt%, the TS-1 content of 9 wt%, the reaction time of 3 hours, the intensity of stirring of 500 rpm and the molar ratio of hydrogen peroxide/Na2SO42:1 to 14:1 (also the results for epoxidation of diallyl ether without Na2SO4were presented)

Determination of Vitamin C Content in Saposhnikovia Divaricata by Capillary Zone Electrophoresis

In this paper, using capillary zone electrophoresis method determined Vitamin C content in saposhnikovia divaricata. 20 mmol/L borax solution and 20% acetonitrile concentration, 20kV voltage, 254 nm UV detection wavelength was chosen for electrophoretic analysis. Measured vitamin C content in saposhnikovia divaricata were 0.297 mg/g (RSD=5.9%) (n=7).

Determination of Vitamin C Content in Brown Rice by Capillary Zone Electrophoresis

In this paper, using capillary zone electrophoresis method determined Vitamin C content in brown rice. 20 mmol/L borax solution and 20% acetonitrile concentration, 20kV voltage, 254 nm UV detection wavelength was chosen for electrophoretic analysis condition. Measured vitamin C content in brown rice was 0.043 mg/g (RSD=7.1%) (n=7).

Separation of Tegafur and its Impurities by Reversed-Phase High-Perfomance Liquid Chromatography

The chromatographic behavior of tegafur and its impurities on a naphthalene Cosmosil piNAP column under reversed-phase high-performance liquid chromatography conditions was examined. A good description of the retention was achieved through the application of statistical weights to the widely used quadratic relationships between the logarithm of the retention factor (log k) and the organic solvent concentration in the mobile phase. Optimum conditions for isocratic separation of the compounds were found with acetonitrile concentration of 10-30% in the mobile phase

Acetonitrile as a possible marker of current cigarette smoking

Volatile nitriles are present in cigarette smoke. We tested the hypothesis that the presence of any of four nitriles in the blood can serve as a marker of recent cigarette smoking. We determined the sensitivity and specificity of these nitriles as indicators of daily cigarette smoking in 24 smokers (Group A) and 18 non-smokers (Group B), as well as the correlation between intensity of daily smoking and the blood concentration of acetonitrile. A new head space GLC assay method was used. Of the four nitriles, only acetonitrile was present in the blood of any study subject. Acetonitrile was moderately sensitive (67%) and entirely specific (100%) for self-reported daily smoking. There was fair correlation between blood acetonitrile concentration and the average daily number of cigarettes smoked (r2=0.39; P=0.001), and the mean blood acetonitrile concentration was significantly higher (P=0.03) among subjects with higher ( > 10 cigarettes per day) current cigarette exposure (148.3 ± 18.0 ?g/l) than among smokers with low or minimal (1-10 cigarettes per day) exposure (43.3 ± 6.0 ?g/l). Thus, acetonitrile in blood appears to be highly specific and a moderately sensitive marker of cigarette smoking with a dose-effect relationship. As such, acetonitrile shows promise as a marker of current cigarette exposure.

Study of Briggs Rauscher Oscillatory Reaction in Aqueous Acetonitrile Mixed Medium

The oscillatory behaviour of two new substrates namely, 2-thenoyltrifluoroacetone and cyanoacetic acid in the Briggs Rauscher (B-R) system was studied in detail employing a mixed medium: aqueous acetonitrile. The effect of acetonitrile concentration on the oscillatory behaviour is investigated. It is found that employing the aqueous organic mixed media is highly beneficial in the oscillatory study, enabling the study of water-insoluble substances.

Improved separation of C12-C22 fatty acid phenacyl esters by reversed phase column liquid chromatography

Phenacyl esters of C12-C22 fatty acids were separated on Separon SGX C18 column, using a gradient elution with methanol-acetonitrile-water. The proposed gradient showed better resolution of the critical pairs C18:3-C14:0, C16:1-C20:4, and C16:0-C18:1 than the gradient elution with methanol-water or acetonitrile-water, or than the isocratic elution with methanol-acetonitrile-water. The optimum volume concentration (83%) of the sum of both methanol and acetonitrile was maintained constant for 35 min; in this period the acetonitrile concentration decreased linearly from the initial 42-60% to 0% while the methanol concentration increased from the initial 41-23% to 83% at the same rate. After 35 min the elution was completed with a methanol-water gradient. The whole analysis can be performed within 63 min at a flow rate 1 ml/min.

II. Rapid Extraction Method for Crops

An ethyl acetate extraction method for organophosphate pesticide residues on crop samples requires about 40 minutes for extraction and preparation of sample. This procedure eliminates the lengthy acetonitrile concentration and reduces the volume of solvent used in the acetonitrile procedure. Dimethoate, diazinon, Trithion, Guthion, Phosdrin, and parathion were easily extracted from field-sprayed kale by the ethyl acetate extraction method.