Synthesis of a highly fluorescent N,N‐dimethyl benzylamine–palladium(II) curcuminate complex and its application for determination of trace amounts of water in organic solvents

In this work a new highly fluorescent N,N‐dimethyl benzylamine–palladium(II) yu complex was synthesized by the reaction of [Pd₂{(C,N–C₆H₄CH₂N(CH₃)₂}₂(μ‐OAc)]₂] with curcumin. The structure of the synthesized complex was characterized using Fourier transform infra‐red (FT‐IR) spectroscopy, ¹H nuclear magnetic resonance spectroscopy, and elemental analysis. Fluorescence quantum yield (Φ_F) values of the synthesized complex in dimethyl sulfoxide (DMSO), acetonitrile, ethanol, and methanol were 0.160, 0.104, 0.068, and 0.061, respectively. The fluorescence signal of the complex in the organic solvents was very sensitive to the water content of the organic solvent. The quenching effect of water was used to determine trace amounts of water in the heteroatom‐containing organic solvents (ethanol, methanol, acetonitrile) and redox‐active solvents (DMSO). The linear ranges for determination of water (v/v %) in ethanol, DMSO and acetonitrile were found to be 0.03–14.5, 0.08–13.8, and 0.07–18.8, respectively. Two linear ranges were found for determination of water (v/v %) in methanol (0.1–1.2 and 4.7–25.0). Detection limit (DL) values were calculated to be 0.001, 0.05, 0.004, and 0.01 (v/v %) in ethanol, methanol, acetonitrile, and DMSO, respectively. The proposed method overcomes the problems of the standard Karl Fischer method for determination of water in DMSO. In addition, it gave the best DL value for determination of water in ethanol compared with all published papers to date.     

A novel gaseous dimethylamine sensor utilizing cataluminescence on zirconia nanoparticles

A novel cataluminescence (CTL) sensor using ZrO₂ nanoparticles as the sensing material was developed for the determination of trace dimethylamine in air samples based on the catalytic chemiluminescence (CL) of dimethylamine on the surface of ZrO₂ nanoparticles. The CTL characteristics and the different factors on the signal intensity for the sensor, including nanomaterials, working temperature, wavelength and airflow rate, were investigated in detail. The CL intensity on ZrO₂ nanoparticles was the strongest among the seven examined catalysts. This novel CL sensor showed high sensitivity and selectivity to gaseous dimethylamine at optimal temperature of 330°C. Quantitative analysis was performed at a wavelength of 620 nm. The linear range of CTL intensity vs concentration of gaseous dimethylamine was 4.71 × 10^?3 to 7.07 × 10^?2 mg L^?1 (r = 0.9928) with a detection limit (3σ) of 6.47 × 10^?4 mg L^?1. No or only very low levels of interference were observed while the foreign substances such as benzene, hydrochloric acid, methylbenzene, chloroform, n‐hexane and water vapor were passing through the sensor. The response time of the sensor was less than 50 s, and the sensor had a long lifetime of more than 60 h. The sensor was successfully applied to the determination of dimethylamine in artificial air samples, and could potentially be applied to analysis of nerve agents such as Tabun (GA). Copyright © 2009 John Wiley & Sons, Ltd.     

Development of a Validated LC Method for Separation of Process‐Related Impurities Including the R‐enantiomer of S‐Pramipexole on Polysaccharide Chiral Stationary Phases

Despite the availability of a few methods for individual separation of S‐pramipexole from its process‐related impurities, no common liquid chromatography (LC) method is reported so far in the literature. The present article describes the development of a single‐run LC method for simultaneous determination of S‐pramipexole and its enantiomeric and process‐related impurities on a Chiralpak AD‐H (150 x 4.6 mm, 5μm) column using n‐hexane/ethanol/n‐butylamine (75:25:0.1 v/v/v) as a mobile phase in an isocratic mode of elution at a flow rate of 1.2 ml/min at 30°C. The chromatographic eluents were monitored at a wavelength of 260 nm using a photodiode array detector. Excellent enantioseparation with good resolutions (Rs ≥ 2.88) and peak shapes (A_s ≤ 1.21) for all analytes was achieved. The proposed method was validated according to International Conference Harmonization (ICH) guidelines in terms of accuracy, precision, sensitivity, and linearity. Limits of quantification of impurities (0.25–0.55 μg/ml) indicate the highest sensitivity achievable by the proposed method. The method has an advantage of selectivity and suitability for routine determination of not only chiral impurity but also all possible related substances in active pharmaceutical ingredients of S‐pramipexole. Chirality 27:430–435, 2015. © 2015 Wiley Periodicals, Inc.     

The effect of various atmospheric conditions on the 2,3-butanediol fermentation from glucose byBacillus polymyxa

The examination of the effect of N₂, air and O₂ on the glucose to 2,3-butanediol fermentation byBacillus polymyxa showed that N₂ sparging resulted in best 2,3-butanediol production at low yeast extract concentration (0.5%, w/v) whereas aeration produced best results with high yeast extract levels (1.2%, w/v). However, under all atmospheric conditions, improvements in rates and yields of 2,3-butanediol production and rates of glucose utilization were observed with high yeast extract. Regardless of the yeast extract levels, highest concentrations of ethanol and acetoin were obtained with N₂ sparging and aeration respectively. No acetoin accumulated under anaerobic (N₂) conditions and no ethanol accumulated with aeration. The rate of glucose utilization, in all fermentations, was highest under N₂ and lowest with O₂ sparging. In addition to the biochemical results, morphological observations with O₂, N₂ and air sparging are also reported.NRCC No. 23868     

An automated continuous determination of oxygen with high sensitivity

A sensitive, rapid, and precise method is described for the continuous determination of oxygen in gases. The principle of the method is based on the reaction of O₂ with an alkaline catechol or pyrogallol solution, which is combined with a Fe²⁺ solution to increase the sensitivity of the color reaction. The development of the color takes place in a tube system provided with a proportioning pump and is read automatically on a recorder after passing a flow cell of a photometer. The lower limit of sensitivity of this method is 0.05 μl of O₂ min^?1. Thus, in a gas flow of ≈0.5 ml min^?1, an oxygen concentration of ≥0.01% (v/v) can be determined. If the gas flow is increased to ≈2.5 ml min^?1, this limit of sensitivity is lowered to ≥0.002% (v/v). Since a 2-min period is necessary for the measurement, the volume of the sample has to be 1 ml in the first case and 5 ml in the second.     

Technological properties of indigenous wine yeast strains isolated from wine production regions of Turkey

The purpose of this study was to evaluate the important technological and fermentative properties of wine yeast strains previously isolated from different wine producing regions of Turkey. The determination of the following important properties was made: growth at high temperatures; fermentative capability in the presence of high sugar concentration; fermentation rate; hydrogen sulfide production; killer activity; resistance to high ethanol and sulfur dioxide; foam production; and enzymatic profiles. Ten local wine yeast strains belonging to Saccharomyces, and one commercial active dry yeast as a reference strain were evaluated. Fermentation characteristics were evaluated in terms of kinetic parameters, including ethanol yield (Y_P/S), biomass yield (Y_X/S), theoretical ethanol yield (%), specific ethanol production rate (q_p; g/gh), specific glucose uptake rate (q_s; g/gh), and the substrate conversion (%). All tested strains were able to grow at 37 °C and to start fermentation at 30° Brix, and were resistant to high concentrations of sulfur dioxide. 60 % of the strains were weak H₂S producers, while the others produced high levels. Foam production was high, and no strains had killer activity. Six of the tested strains had the ability to grow and ferment at concentrations of 14 % ethanol. Except for one strain, all fermented most of the media sugars at a high rate, producing 11.0–12.4 % (v/v) ethanol. Although all but one strain had suitable characteristics for wine production, they possessed poor activities of glycosidase, esterase and proteinase enzymes of oenological interest. Nine of the ten local yeast strains were selected for their good oenological properties and their suitability as a wine starter culture.     

Research on benzene,toluene and dimethylbenzene detection based on a cataluminescence sensor

We present a sensitive and quick way to determine benzene, toluene and dimethylbenzene (BTEX) in air, applying a cataluminescence (CTL) sensor based on a nano‐sized composite material, γ‐Al₂O₃/PtO₂. The factors that affect the sensor's performance were studied, including the sensing material, temperature, rate of air carrier and wavelength. It was shown that when Pt accounted for 0.2% of the sensing material, the rate of the air carrier that carries target gas was 450 mL/min, the determination wavelength was 400 nm and temperature was 236°C, this sensor showed the best CTL intensity to BTEX. In addition, the CTL intensity had a high linear relation with the concentration of BTEX, with a linear range from 0.5 to 100 mL/m³, and a detection limit 0.22 mL/m³. This nano‐sized material had a quick response within 1.5 s, short recovery time within 1 min and a long lifetime, showing good potential for a variety of applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Influence of dissolved oxygen and shear conditions on clavulanic acid production by Streptomyces clavuligerus

Clavulanic acid (CA), a potent β-lactamase inhibitor, is produced by a filamentous bacterium. Here, the effect of DO and shear, expressed as impeller tip velocity, on CA production was examined. Cultivations were performed in a 4 L fermentor with speeds of 600, 800 and 1,000 rpm and a fixed air flow rate (0.5 vvm). Also, cultivation with automatic control of dissolved oxygen, at 50% air saturation, by varying stirrer speed and using a mixture of air and O₂ (10% v/v) in the inlet gas, and a cultivation with fixed stirrer speed of 800 rpm and air flow rate of 0.5 vvm, enriched with 10% v/v O₂, were performed. Significant variations in CA titer, CA production rate and O₂ uptake-rate were observed. It was also found that the DO level has no remarkable effect on CA production once a critical level is surpassed. The most significant improvement in CA production was related to high stirrer speeds.     

The inhibitory effect of ethanol on ethanol production by Zymomonas mobilis

Summary In an effort to establish the reasons for the limitations in the final ethanol concentration of Zymomonas mobilis fermentation, the effects of CO₂ and ethanol on the fermentation were investigated using continuous and fed-batch cultivation systems. The nucleation and stripping out of CO₂ from the fermenter using diatomaceous earth or nitrogen gas or both exhibited a profound effect on the glucose uptake rate during the early stages of fed-batch fermentation, but did not improve final ethanol yields. The addition of ethanol together with above mentioned experiments confirmed conclusively that ethanol inhibition is responsible for the final ethanol concentration obtainable during Zymomonas mobilis fermentation. The final concentration lies between 90 and 110 gl⁻¹ or approximately 12–15% (v/v) ethanol.     

Ionic liquid ethanol sensor

Ionic liquids containing lithium methylsulfonyl group were prepared from the precursors poly(propylene glycol)-block-(ethylene glycol)-block-(propylene glycol)-bis(2-aminopropyl ether) with different molecular weight. These liquids revealed excellent electrical conductivity in the temperature range -25 to 85 degrees C. Also, they exhibited a high boiling temperature and hence a low vapor pressure in ambient condition. Additionally, they showed a high fluidity with their viscosities being comparative with that of water. To determine the sensitivity of an ethanol sensor by using these ionic liquids, these liquids were subjected into a sequential electrochemical tests with nickel electrodes which performed a high sensitivity for the ethanol sensor. It was found that only the derivative with low molecular weight could detect ethanol. Furthermore, a linear relationship between the response current and the concentration of ethanol was constructed. The detection limit was found to be 0.13% (v/v) and its response time was 336 s.     

Rapid ethanol fermentation of cellulose hydrolysate. I. Batch versus continuous systems

Rapid fermentation of bagasse hydrolysate to ethanol under anaerobic conditions by a strain of Saccharomyces cerevisiae has been studied in batch and continuous cultures at pH 4.0 and 30°C temperature with cell recycle. By using a 23.6 g/liter cell concentration, a concentation of 9.7% (w/v)ethanol was developed in a period of 6 hr. The rate of fermentation was found to increase with supplementation of yeast vitamins in the hydrolysate. In continuous culture employing cell recycle and a 0.127 v/v/m air flow rate, a cell mass concentration of 48.5 g/liter has been achieved. The maximum fermentor productivity of ethanol obtained under these conditions was 32.0 g/liter/hr, which is nearly 7.5 times higher than the normal continuous process without cell recycle and air sparging. The ethanol productivity was found to decrease linearly with ethanol concentration. Conversion of glucose in the hydrolysate to ethanol was achieved with a yield of 95 to 97% of theoretical.     

A chemostat study of ethanol inhibition

The mode of ethanol action on both the steady-state and the dynamic properties of K. aerogenes was investigated using a nitrogen-limited chemostat. Reduction in the maximum growth rate (μ_m) suggests that noncompetitive enzyme inhibition could occur, but Lineweaver–Burk analysis showed the inhibition to be more complex. A consistent mechanism of inhibition was established for 0–3% v/v ethanol. Warburg manometric experiments indicated that inhibition occurred in pathways located in the intact cell wall. Frequency response analysis, using sinusoidal variations in the dilution rate showed that ethanol increased the time constant of the metabolic parameter, Q_AC. The system was stable in the presence of ethanol and showed no evidence of oscillations following a disturbance.     

A New Pyridoxamine 5′-Phosphate–α-Ketoglutaric Acid Transaminase (Pyridoxamine 5′-phosphate:2-Oxoglutarate Aminotransferase)

A thin-layer chromatographic method is described for the separation, identification and determination of 2,4-dinitrophenyl sulfides. The derivatives are easily obtained from mercaptan and dinitrofluorobenzene in the presence of sodium bicarbonate at room temperature. The sulfides are separated on silica gel plates using a solvent mixture of benzene-xylene-carbon tetrachloride (2:1:1, v/v). The individual sulfides are determined spectrophotometrically, at 330~335 mμ in ethanol, ε_max ca. 13,000, after washing out the plate with hexane and extraction from the adsorbent with acetone.     

Designing a Non-invasive Surface Acoustic Resonator for Ultra-high Sensitive Ethanol Detection for an On-the-spot Health Monitoring System

Surface acoustic wave (SAW) sensors–based on piezoelectric crystal resonators–are extremely sensitive to even very small perturbations in the external atmosphere, because the energy associated with the acoustic waves is confined to the crystal surface. In this study, we present a critical review of the recent researches and developments predominantly used for SAW-based organic vapor sensors, especially ethanol. Besides highlighting their potential to realize real-time ethanol sensing, their drawbacks such as indirect sensing, invasive, time initializing, and low reliability, are properly discussed. The study investigates a proposed YZ-lithium niobate piezoelectric substrate with interdigital transducers patterned on the surface. Design of the resonator plays an important role in improving mass sensitivity, particularly the sensing area. Accordingly, a tin dioxide (SnO₂) layer with a specific thickness is generated on the surface of the sensor because of its high affinity to ethanol molecules. To determine the values of sensor configuration without facing the practical problems and the long theoretical calculation time, it is shown that the mass sensitivity of SAW sensors can be calculated by a simple three-dimensional (3-D) finite element analysis (FEA) using a commercial finite-element platform. In design validation step, different concentrations of ethanol are applied to investigate the acoustic wave properties of the sensor. The FEA data are used to obtain the surface and bulk total displacements of the sensor and fast Fourier transform (FFT) on output spectrum. The sensor could develop into highly sensitive and fast responsive structure so that a positive intensity shift of 0.18e-2 RIU is observed when the sensor is exposed to 15 ppm ethanol. It is capable of continuously monitoring the ethanol gas whether as an ultra-high sensitive sensor or switching applications for medical and industrial purposes.     

A combination of methods for the on-line determination of alcohols in microbial cultures

Summary A new method for the continuous on-line determination of methanol (range 0.2 to 10 gl^–1) and ethanol (0.2 to 120 gl^–1) is described. The rate limiting step is diffusion of the alcohol through the walls of a silicone tube immersed in the culture broth. A sintered SnO₂ sensor was used instead of a Flame Ionization Detector for alcohol determination. Measurement is not affected by bioreactor aeration or agitation rates, dissolved oxygen, carbon dioxide, ammonia or the concentration of cells in the medium. The assay system was tested in extended batch cultivation of Methylomonas sp. with methanol as the sole carbon source (final biomass concentration, 35 gl^–1). Sensor readings agreed well with simultaneous off-line gas chromatographic methanol determination.     

Optimization of extraction process by response surface methodology and preliminary structural analysis of polysaccharides from defatted peanut (Arachis hypogaea) cakes

In this work, response surface methodology was used to determine optimum conditions for extraction of polysaccharides from defatted peanut cake. A central composite design including independent variables, such as extraction temperature (x₁), extraction time (x₂), and ethanol concentration (x₃) was used. Selected response which evaluates the extraction process was polysaccharide yield, and the second-order model obtained for polysaccharide yield revealed coefficient of determination of 97.81%. The independent variable with the largest effect on response was ethanol concentration (x₃). The optimum extraction conditions were found to be extraction temperature 48.7 °C, extraction time 1.52 h, and ethanol concentration of 61.9% (v/v), respectively. Under these conditions, the extraction efficiency of polysaccharide can increase to 25.89%. The results of structural analysis showed that the main composition of defatted peanut cake polysaccharide was α-galactose.     

Fabrication of Smart Chemical Sensors Based on Transition-Doped-Semiconductor Nanostructure Materials with μ-Chips

Transition metal doped semiconductor nanostructure materials (Sb₂O₃ doped ZnO microflowers, MFs) are deposited onto tiny µ-chip (surface area, ∼0.02217 cm²) to fabricate a smart chemical sensor for toxic ethanol in phosphate buffer solution (0.1 M PBS). The fabricated chemi-sensor is also exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards ethanol. The calibration plot is linear (r² = 0.9989) over the large ethanol concentration ranges (0.17 mM to 0.85 M). The sensitivity and detection limit is ∼5.845 µAcm⁻²mM⁻¹ and ∼0.11±0.02 mM (signal-to-noise ratio, at a SNR of 3) respectively. Here, doped MFs are prepared by a wet-chemical process using reducing agents in alkaline medium, which characterized by UV/vis., FT-IR, Raman, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM) etc. The fabricated ethanol chemical sensor using Sb₂O₃-ZnO MFs is simple, reliable, low-sample volume (<70.0 µL), easy of integration, high sensitivity, and excellent stability for the fabrication of efficient I–V sensors on μ-chips.     

Simultaneous determination of albendazole sulfoxide enantiomers and albendazole sulfone in plasma

A high-performance liquid chromatographic method has been developed for the simultaneous determination of albendazole sulfoxide (ABZSO) enantiomers and albendazole sulfone (ABZSO₂) in human plasma. The resolution of ABZSO enantiomers and ABZSO₂ was obtained on a Chiralpak^® AD column using hexane–isopropanol–ethanol (81:14.25:4.75, v/v/v) as the mobile phase. The drugs were detected by fluorescence (λ_exc=280 nm, λ_em=320 nm). The drugs were extracted from 500 μl plasma with ethyl acetate, and after solvent evaporation, the residues were dissolved in the mobile phase and chromatographed. The method was precise and accurate for the three compounds, as judged by the coefficients of variation and relative errors observed. Linear standard curves were obtained in the concentration range of 5–2500 ng/ml for ABZSO enantiomers and 1–500 ng/ml for ABZSO₂. A typical plasma concentration–time profile is presented for one patient under treatment for neurocysticercosis.     

Adaptation of the Cyanobacterium Anabaena variabilis to Low CO(2) Concentration in Their Environment

The rate of adaptation of high CO₂ (5% v/v CO₂ in air)-grown Anabaena to a low level of CO₂ (0.05% v/v in air) was determined as a function of O₂ concentration. Exposure of cells to low (2.6%) O₂ concentration resulted in an extended lag in the adaptation to low CO₂ concentration. The rate of adaptation following the lag was not affected by the concentration of O₂. The length of the lag period is markedly affected by the O₂/CO₂ concentration ratio, indicating that the signal for adaptation to low CO₂ may be related to the relative rate of ribulose-1,5-bisphosphate carboxylase/oxygenase activities, rather than to CO₂ concentration proper. This suggestion is supported by the observed accumulation of phosphoglycolate following transfer of cells from high to low CO₂ concentration.     

An ethyl acetate sensor utilizing cataluminescence on Y2O3 nanoparticles

A cataluminescence (CTL) sensor using Y₂O₃ nanoparticles as the sensing materials was proposed for the determination of ethyl acetate. This ethyl acetate sensor showed high sensitivity and specificity at the optimal temperature of 264°C. Quantitative analysis was performed at a wavelength of 425 nm. The linear ranges of CTL intensity vs ethyl acetate concentrations were 2.0–250 ppm (r = 0.9965) and 250–6500 ppm (r = 0.9997) with a detection limit (3σ) of 0.5 ppm. There was no response or weak response when foreign substances such as formic acid, n‐hexane, toluene, acetic acid, benzene, and formaldehyde passing through the surface of Y₂O₃ nanoparticles. The sensor had a long lifetime more than 80 h with 3600 ppm ethyl acetate. It had been applied successfully to determine ethyl acetate in artificial air samples. Copyright © 2009 John Wiley & Sons, Ltd.