Preconcentration of rifampicin prior to its efficient spectroscopic determination in the wastewater samples based on a nonionic surfactant

Every year, tuberculosis affects the lungs of millions of people and rifampicin is the commonly used medicine for its treatment due to its antibiotic nature. The frequent use of rifampicin may lead to its increased concentration in the water resources. This research work is focused on the cloud point extraction (CPE) procedure for the preconcentration of rifampicin prior to its determination in water. The UV/vis spectrophotometric method was adapted for the measurement of rifampicin content after the phase separation. Triton-X 100 was used as the nonionic surfactant which contains hydrophilic polyethylene chain feasible for the extraction of analyte. Various analytical parameters that can affect the extraction efficacy were optimized to achieve linearity of the proposed method in the concentration range of 3.54–81.41 mgL^–1. The Limit of detection and quantification were 1.261 and 4.212 mgL^–1, respectively. The Preconcentration factor was 40 with relative standard deviation (%RSD) of 2.504%. The standard addition methodology was adopted for the validation of this procedure and effectively applied for the determination of rifampicin in real wastewater samples.     

Synthesis, Characterization, and Biological Activity of n -Tributyltin Derivatives of Pharmaceutically Active Carboxylates

 Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). ¹¹⁹Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin.     

Al(OTf)3 as a highly efficient catalyst for the rapid acetylation of alcohols, phenols and thiophenols under solvent-free conditions

Aluminium triflate (0.01-0.1 mol %) was found to be an efficient catalyst for the acylation of alcohols, phenols, thiols and sugars with acetic anhydride in high yields under solvent-free conditions in a short reaction time at room temperature. Racemization of optically active alcohols and epimerization of sugars were not observed. The acylation efficacy of various acyl donors was also investigated.     

Generalized I-nonexpansive selfmaps and invariant approximations

Common fixed point results for new classes of noncommuting selfmaps satisfying generalized I-contraction or I-nonexpansive type conditions are established. We apply them to obtain several invariant approximation results which unify, extend, and complement the well-known results.     

Synthesis and physicochemical studies of ferrocene‐containing materials

Low‐temperature solution‐phase polycondensation of 1,1′‐ferrocenedicarboxylic acid chloride with newly synthesized aromatic diamines was carried out in tetrahydrofuran in the presence of triethylamine to form several new organometallic aromatic polyamides containing ferrocene units. The organometallic aromatic polyamides derived were in good yields ranging from 75 to 80%, amorphous with melting temperatures of > 350 °C. The monomers and the resulting polymers were characterized by their physical properties, elemental analysis, 1 H NMR and FTIR spectroscopy. The differential scanning calorimetry and thermogravimetric studies of the resulting aramids were also carried out. All the polymers were insoluble in common organic solvents. However, all dissolved in concentrated H₂SO₄ forming reddish brown solutions. Their glass transition temperatures were quite high, which is characteristic of aramids. They were also stable up to 450 °C with 10% mass losses (14–23%) recorded in the range 400–470 °C. The activation energies for decomposition of each aramid were also calculated using the Horowitz and Metzger method. All polymers showed reduced solution viscosities in concentrated sulphuric acid, which may be attributed to non‐Newtonian behavior. Copyright © 2007 John Wiley & Sons, Ltd.     

Particular solutions of equations of motion of nonholonomic systems

This paper uses the Poincaré formalism to obtain a generalization of the Levi-Cività theorem so as to construct particular solutions of the equations of motion of nonholonomic dynamical systems which admit a given set of invariant relations. Sufficient conditions allowing such a generalization are established.     

On invariant random approximations

A result regarding invariant random approximation is proved. Supported by Kuwait University Research Grant No. SM-119.     

Synthesis,characterization, POM analysis and antifungal activity of novel heterocyclic chalcone derivatives containing acylated pyrazole

Research on Chemical Intermediates - A series of heterocyclic chalcone derivatives (4a–h) were synthesized and characterized by IR, 1H and 13C NMR as well as MS. All the synthesized compounds...