Optimization of a novel method based on solidification of floating organic droplet by high-performance liquid chromatography for evaluation of antifungal drugs in biological samples

In this study, a simple, rapid, and highly efficient liquid-phase microextraction method based on solidification of floating organic droplet was coupled with high performance liquid chromatography-photo diode array detection (HPLC-PDA) for determination of ketoconazole, clotrimazole, and miconazole as antifungal drugs. Central composite design (CCD) was used for optimization of several factors affecting the extraction efficiency. The optimized conditions were established to be 550 rpm for stirring rate, 35 min for extraction time, 57 °C for extraction temperature, 8.5 for solution pH, 10 μl for organic solvent volume, and 7% (w/v) of NaCl for ionic strength. Limit of detections (LODs) of the extraction method ranged from 0.01 to 0.1 μg L⁻¹ and the linear dynamic ranges (LDRs) ranged from 0.1 to 300 μg L⁻¹ for the three antifungal drugs. Relative standard deviations (RSDs) of the proposed method were 5-11%. Preconcentration factors in the range of 306-1350 were obtained at extraction time of 35 min. Finally, performance of the proposed method was evaluated for the extraction and determination of the drugs’ levels in microgram per liter in samples and satisfactory results were obtained.     

Pyrophosphate Selective Recognition in Aqueous Solution Based on Fluorescence Enhancement of a New Aluminium Complex

A novel and simple fluorescence enhancement method for selective pyrophosphate(PPi) sensing was proposed based on a 1:1 metal complex formation between bis(8-hydroxy quinoline-5-solphonat) chloride aluminum(III) (Al(QS)₂Cl), (L) and PPi in aqueous solution. The linear response range covers a concentration range of 1.6 × 10⁻⁷ to 1.0 × 10⁻⁵ mol/L of PPi and the detection limit of 2.3 × 10⁻⁸ mol/L. The association constant of L-PPi complex was calculated 2.6 × 10⁵ L/mol. L was found to show selectively and sensitively fluorescence enhancement toward PPi over than I₃^-, NO₃^-, CN⁻, CO₃²⁻, Br⁻, Cl⁻, F⁻, H₂PO4⁻ and SO₄²⁻, which was attributed to higher stability of inorganic complex between pyrophosphate and L.     

A Carbon Material as a Strong Protonic Acid for Efficient Synthesis of 4(3H)‐Quinazolinones

Carbon‐based solid acid catalyst has been applied to catalyzing the synthesis of 4(3H)‐quinazolinones from the cyclization reaction of 2‐aminobenzamide with aroyl chlorides. The results showed that the catalyst was very efficient with the average yield over 85%. This carbon material with strong protonic acid sites as heterogeneous catalyst has some advantages such as high activity, strikingly simple work‐up procedure, non‐pollution, and reusability, which will contribute to the green process greatly.     

Silica Gel‐Supported Polyphosphoric Acid (PPA/SiO2): An Efficient and Reusable Heterogeneous Catalyst for Facile Synthesis of 14‐Aryl‐14H‐dibenzo[a,j]xanthenes under Solvent‐free Conditions

A simple, efficient and green method for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes by a one‐pot condensation reaction of β‐naphthol and aryl aldehydes using silica gel‐supported polyphosphoric acid (PPA/SiO₂), an effective and reusable catalyst, under solvent‐free conditions is described. The present methodology offers several advantages, such as a simple procedure with an easy work‐up, short reaction times, high yields, and the absence of any volatile and hazardous organic solvents.     

An Efficient One‐Pot,Four‐Component Synthesis of {[(1H‐1,2,3‐Triazol‐4‐yl)methoxy]phenyl}‐1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione Derivatives

The 1‐{[(1H‐1,2,3‐Triazol‐4‐yl)methoxy]phenyl}‐1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives 5 were synthesized by a simple and efficient method, i.e., by the four‐component, one‐pot condensation reaction of phthalohydrazide 4 , a (propargyloxy)benzaldehyde 1 , an active methylene compound 3 (malononitrile or ethyl cyanoacetate), and an azide 2 in the presence of Cu(OAc)₂/sodium L ‐ascorbate as catalyst and 1‐methyl‐1H‐imidazolium trifluoroacetate ([Hmim](CF₃COO)) as an ionic‐liquid medium in good to excellent yields (Scheme 1).     

Solvent‐free synthesis of new 2,4,6‐triarylpyridines catalyzed by a Brønsted acidic ionic liquid as a green and reusable catalyst

Some new 4‐(aryl)‐2,6‐di‐2‐naphthylpyridines and 4‐(aryl)‐2,6‐di‐2‐thienylpyridines have been prepared through three‐component condensation of 2‐acetylnaphthalene or 2‐acetylthiophene, aromatic aldehydes, and ammonium acetate in presence of 1‐(4‐sulfonylbutyl) pyridinium hydrogensulfate [(CH₂)₄SO₃HPy][HSO₄], a Brønsted acidic ionic liquid as a green and reusable catalyst in solvent‐free conditions. Also some new 4,4'‐(1,4‐phenylene)‐bis‐(2,6‐di‐aryl pyridine) was prepared. J. Heterocyclic Chem., (2011).     

Oxidative properties of a nonheme Ni(II)(O2) complex: Reactivity patterns for C-H activation, aromatic hydroxylation and heteroatom oxidation

Density functional theory calculations on the reactivity of a Ni(II)-superoxo complex in C-H bond activation, aromatic hydroxylation and heteroatom oxidation reactions have been explored; the Ni(II)-superoxo complex is able to react with substrates with weak C-H bonds and PPh(3).     

Detection and dosimetry of gamma ray emitted from thallium-201 and technetium-99m based on chemiluminescence technique

This report describes the detection and dosimetry of gamma ray emitted from Thallium-201 (²⁰¹Tl) and Technetium-99m (^99mTc) based on chemiluminescence technique. H₂O₂ produced by two gamma emitter radioisotopes of ²⁰¹Tl and ^99mTc were quantitatively measured by chemiluminescence method. Upon producing H₂O₂ in a luminol alkaline solution, in the presence of diperiodatocuprate, as catalyst a chemical reaction was accrued and consequently the emitted light was measured. The determined H₂O₂ concentration was correlated with the gamma ray detection and dosimetry. The sensitivity of chemiluminescence technique for ²⁰¹Tl and ^99mTc dosimetry was determined to be 0.20 and 0.08 MBq/l (Mega Becquerel per liter) respectively (R.S.D. = %5, N = 3). The plotted calibration curves showed detection limits of 3.24 and 1.76 MBq/l for ²⁰¹Tl and ^99mTc, respectively.     

Shielding failure rate calculation by means of downward and upward lightning leader movement models: Effect of environmental conditions

In this paper the effects of environmental conditions on shielding failure rate (SFR) of transmission lines are investigated. The study utilizes a previously published work in which leader progression model for lightning upward and downward leaders are used to calculate the SFR. Taking into account the effects of reduced air density and humidity on the parameters of upward leader model and wind pressure on the movement of lightning leaders and wires, SFR and maximum lightning stroke current causing shielding failure are computed. The electric field in all simulations is calculated by means of charge simulation method. The results of simulation show that the effects of relative air density and height of installation are quite higher than that of the wind pressure and humidity while the humidity has the lowest impact on the SFR of investigated transmission line.