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Synthesis of alkyl ((5‐[alkylamino]‐1,3,4‐thiadiazol‐2‐yl)methyl)carbamodithioates via the reaction of glycine‐based dithiocarbamates with thiosemicarbazides in the presence of POCl3 in ethanol is disclosed. The main advantages of this method including the use of ethanol as solvent, no need to column chromatography for purification and high to excellent yields of products are noteworthy. [ABSTRACT FROM AUTHOR]

A novel voltammetric method for the determination of trifluralin is proposed based on a composit of carbon paste and copper nanowire as a sensitive sensor. The presence of copper nanowire in the composite film enhance the conductivity and as a result increased the electron transfer rate constant and so the current will increase. The composite exhibits a promising higher electrocatalytic activity towards the oxidation of trifluralin in pH 4.0 aqueous solution. The reduction peak currents of trifluralin increased remarkably and the reduction peak potential shifted positively at the nanostructuring electrode, compared with that at a bare CPE which show the enhanced effect of nanowire. The support electrolyte to provide a more defined and intense peak current for trifluraline determination was 0.05 mol L phosphate buffer at pH 4.0. The fast Fourier transform square wave voltammetry was used as a new electrochemical technique in flow injection system to abtain more sensitivity by application of discrete fast Fourier transform method by background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window, the signal-to-noise ratio has significantly increased and made the sensivity to be higher than other methods. The effective parameters such as frequency, amplitude, and pH were optimized to get the best sensitivity. As a result, the sensor showed a valuable response in linear concentration range of 100-0.02 nmol L with a (limit of detection) LOD of 0.008 nmol L and (limit of quantification) LOQ of 0.15 nmol L for trifluralin. A good recovery was obtained for assay spiked urine samples and a good quantification of trifluralin was achieved in soil samples. [ABSTRACT FROM AUTHOR]

A new detection technique called Fast Fourier Transform Square-Wave Voltammetry (FFT SWV) is based on measurements of electrode admittance as a function of potential. The response of the detector (microelectrode), which is generated by a redox processes, is fast, which makes the method suitable for most applications involving flowing electrolytes. The carbon paste electrode was modified by nanostructures to improve sensitivity. Synthesized dysprosium nanowires provide a more effective nanotube-like surface [1-4] so they are good candidates for use as a modifier for electrochemical reactions. The redox properties of diclofenac were used for its determination in human serum and urine samples. The support electrolyte that provided a more defined and intense peak current for diclofenac determination was a 0.05 mol L-1 acetate buffer pH = 4.0. The drug presented an irreversible oxidation peak at 850 mV vs. Ag/AgCl on a modified nanowire carbon paste electrode which produced high current and reduced the oxidation potential by about 100 mV. Furthermore, the signal-to-noise ratio was significantly increased by application of a discrete Fast Fourier Transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. To obtain the much sensivity the effective parameters such as frequency, amplitude and pH was optimized. As a result, CDL of 2.0 × 10-9 M and an LOQ of 5.0 × 10-9 M were found for the determination for diclofenac. A good recovery was obtained for assay spiked urine samples and a good quantification of diclofenac was achieved in a commercial formulation. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between paracetamol and human serum albumin (HSA) under physiological conditions has been investigated by fluorescence, circular dichroism (CD) and docking. Fluorescence data revealed that the fluorescence quenching of HSA by paracetamol was the result of the formed complex of HSA–paracetamol, and the binding constant (K a) and binding number obtained is 1.3×104 at 298K and 2, respectively for the primary binding site. Circular dichorism spectra showed the induced conformational changes in HSA by the binding of paracetamol. Moreover, protein–ligand docking study indicated that paracetamols (two paracetamols bind to HSA) bind to residues located in the subdomain IIIA. [Copyright &y& Elsevier]

Abstract: This paper presents the optimization of instrumental and solution parameters for determination of tamoxifen in urine and plasma and formulation by fast Fourier transform square wave voltammetry (SWV) using a gold microelectrode in flow-injection system. The samples are subjected by the same buffer solution and are injected in the flow-injection apparatus. By applying a novel square wave voltammetry method to perform as a sensitive method the voltamograms are recorded. The method used for determination of tamoxifen by measuring the changes in admittance voltammogram of a gold ultramicroelectrode (in 0.05molL−1 H3PO4 solution) caused by adsorption of the tamoxifen on the electrode surface. The best sensitivity was achieved using a frequency of 600Hz and a medium composed of 0.05molL−1 phosphate buffers at pH 2.0. The best performance was obtained with the pH value of 2, pulse amplitude 25mV, frequency 600Hz, accumulation potential of −100mV and accumulation time of 0.5s. Furthermore, signal-to-noise ratio has significantly increased by application of discrete fast Fourier transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. Calibration plots are given for solutions containing 1.0×10−11 to 3.0×10−6 molL−1 of tamoxifen. The detection limit is calculated to be 3.0×10−12 molL−1 (∼2pgmL−1). The relative standard deviation at concentration 2.0×10−8 M is 6.1% for five reported measurements. [Copyright &y& Elsevier]

This study illustrates a novel method for fast monitoring of tetracycline in flow-injection systems. The fast Fourier transformation, along with continuous cyclic voltammetry (FFTCV) at a gold microelectrode in a flowing solution system, was used for the determination of tetracycline in its pharmaceutical formulation. The benefit of the developed technique is that it is simple, precise, accurate, time-saving, and economical compared to all of the previously reported methods. The effects of various parameters on the sensitivity of the method were investigated. Three considerable advantages are demonstrated by this method, which other methods do not possess. Firstly, there is no requirement for oxygen removal from the test solution; secondly, a picomolar detection limit is gained; and, finally, rapid determination of any such compound in a broad range of chromatographic methods. As a result, the method was found to be linear over the concentration range of 16-440 pg/mL (r = 0.9962), with a limit of detection and quantitation of 4.5 and 16 pg/mL, respectively. Furthermore, the technique shows the requisite accuracy, sensitivity, precision, and selectivity to assay tetracycline in capsules. [ABSTRACT FROM AUTHOR]

A highly selective and sensitive triiodide sensor based on a 2-(((2-(((E)-1-(2-hydroxy phenyl) methylidine) amino) phenyl) imino) methyl) phenol with iodine (CTC) as membrane carrier was developed. The electrode revealed a Nernstian behavior over a very wide triiodide-ion concentration range (5.0×10 -8 –1.0×10 -2 M), and relatively low detection limit (3.0×10 -8 M). The potentiometric response is independent of the pH of solution in the pH range of 3.0–10.0. The electrodes manifest advantages of low resistance, very fast response ( [ABSTRACT FROM AUTHOR]

This research demonstrates the quick guthion monitoring with the help of a sensitive method called fast Fourier transformation continuous cyclic voltammetry (FFTCV). Fortunately, FFTCV illustrates the benefits of precision, determination speed, cost-effectiveness, accuracy and simplicity, in comparison with formerly reported techniques. In particular, this method was applied to a gold microelectrode in flowing solutions to detect the guthion concentration in its formulations. The effects of several parameters were examined regarding the sensitivity of the method. After a series of experiments, the detection limit of the method was found to be equal to 1. 27pg/mL, when the optimum conditions were imposed, which is a scan rate value of 40V/s, an accumulation time of 0. 4s, an accumulation potential of 0mV and a pH value of 2. During the measurements performance, the integration range of currents included all the potential scan ranges, even the oxidation and reduction of the Au surface electrode, for the achievement of a sensitive determination. Then, the potential waveform, consisting of the potential steps for cleaning, accumulation and the step for the potential ramp, was applied to an Au disk microelectrode in a continuous way. It is also important to refer to the positive points, presented only by the use of this technique. Firstly, it is no longer necessary to remove the oxygen from the test solution. Furthermore, the quick determination of any such compound in many chromatographic methods is possible. Thirdly, the corresponding detection limit is of nanomolar level. [Copyright &y& Elsevier]

An electroanalytical method has been developed for the determination of the ketotifen by continuous square wave adsorptive stripping voltammetry on a ultra-gold microelectrode (Au UME) in aqueous solution with phosphate buffer as supporting electrolyte. The best adsorption conditions were found to be pH 2.3, an accumulation potential of 300 mV (Au vs. Ag: AgCl-KCl 3 M) and an accumulation time of 400 ms. Variation of admittance in the detection process is created by inhibition of oxidation reaction of the electrode surface, by adsorption of ketotifen. Furthermore, signal-to-noise ratio was significantly increased by application of discrete fast Fourier transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. Also in this work some parameters such as square-wave frequency, eluent pH, and accumulation time were optimized. Effects of square-wave frequency, step potential and pulse amplitude were examined for the optimization of instrumental conditions. The calibration curve is linear in the range 2.0x10(-7)---5.0x10(-12) M with a detection limit of 2.0x10(-12) M (ca. 0.7 pg/ml). The method maybe applied direct determination of the drug in pharmaceutical and biological samples. For a concentration of 5.0x10(-8) M a recovery value of 99.89% is obtained.