Determination of cetirizine in tablets and compounded capsules: comparative study between CE and HPLC

A capillary electrophoresis (CE) method was developed and validated for determination of cetirizine dihydrochloride in tablets and compounded capsules. The electrophoretic separation was performed in an uncoated fused-silica capillary (40 cm x 50 μm i.d.) using 20 mmol L-1 sodium tetraborate buffer (pH 9.3) as background electrolyte, a hydrodinamic sample injection at 50 mBar for 5 s, 20 KV applied voltage at 25 °C, and detection at 232 nm. The proposed method was compared with the high performance liquid chromatographic (HPLC) method previously validated for this drug, and statistical analysis showed no significant difference between the techniques.

Salinidade em petróleo bruto: otimização de metodologia e proposta de um novo método para extração de sais em petróleo

The quantity of salts in the crude oils depends on the origin and of the wells production and these salts cause several problems during the transport and the process of refine as corrosions, incrustations and deactivation of the employed catalysts in the refineries. In this study were implemented changes for improvements in the execution of ASTM D 6470 method and has also developed a new methodology of extraction system of salts using process of mechanical agitation without heating. The results of the optimization produce larger efficiency and safety to the process compared to the traditional ASTM method.

Austin, dehydroaustin and other metabolites from Penicillium brasilianum

A culture of P. brasilianum, isolated from soil collected at the Serra do Cipó National Park, in Minas Gerais State (Brazil), was grown for 25 days on a dextrose-peptone-salts medium. The corresponding ethylacetate extract was column chromatographed and four compounds were isolated: austin, dehydroaustin, D-mannitol and penicillic acid. This is, in the best of our knowledge, the first time that the meroterpenes austin and dehydroaustin have been isolated from this species. Activity of the extract and isolated compounds was tested against six bacteria and for acetylcholinesterase inhibition. Penicillic acid showed high activity in both tests.

Efecto del catión, del anión y del co-ión sobre la agregación de líquidos iónicos en solución acuosa

The aggregation behavior of thirteen 1-alkyl-3-methylimidazolium based ionic liquids in aqueous solution is presented, considering variations of the alkyl side chain length as well as the anionic moiety. Cation and anion molecular volumes are selected as appropriate molecular descriptors. Additionally, the existing relationship between critical micelle concentration (CMC) and electrolyte concentration in solution is established, aiming to clarify ion effects. CMC values were obtained by measuring electrical conductivity and surface tension. It was confirmed that aggregation of ionic liquids in aqueous solution and in presence of inorganic salts is affected by the factors developed in this study.

Fracionamento de polifosfato de sódio e caracterização por RMN de 31P: um experimento para aulas de físico-química

This text describes an experiment on fractional precipitation of a polymer together with determination of average degree of polymerization by NMR. Commercial sodium polyphosphate was fractionated by precipitation from aqueous solution by adding increasing amounts of acetone. The polydisperse salt and nine fractions obtained from it were analyzed by 31P Nuclear Magnetic Resonance and the degree of polymerization of the salts and of the fractions were calculated. Long-chain sodium polyphosphate was also synthesized and analyzed. This experiment was tested in a PChem lab course but it can be used also to illustrate topics of inorganic polymers and analytical chemistry.

Arylation of β,γ-unsaturated lactones by a Heck-Matsuda reaction: an unexpected route to aryldiazene butenolides and pyridazinones

The palladium catalysed coupling of aryldiazonium salts with β-γ-unsaturated lactones under basic conditions has been investigated. Both (3H)-furanone and α-angelicalactone were evaluated as substrates in the Heck Matsuda reaction but both failed to afford the desired arylated butenolides. Under basic conditions, β-γ-unsaturated lactones generate highly nucleophilic enolates that preferentially undergo azo coupling reactions with arenediazonium salts to afford aryldiazene butenolides. The electronic and steric effect of the substituents on the aryldiazonium salt in the azo coupling reaction is described. Aryldiazene-lactone derivatives were obtained in good yields from a highly facile and straightforward procedure. An aminoisomaleimide was formed from (3H)-furanone and cyclised to the corresponding pyridazinones in modest yield.

Avaliação físico-química de efluente gerado em biodigestor anaeróbio para fins de avaliação de eficiência e aplicação como fertilizante agrícola

The use of biodigester for basic and environmental sanitation has large demand in Brazil. A biodigester was built to treat conjunctly the human and pig feces and urine, regarding to its future application in rural small towns. The results show that the biodigester can reduce 90% of COD and BOD and, up to 99.99% of thermotolerant coliforms. The treated effluent has variable quantities of macro- and micro-nutrients; and organic matter. However, the concentration variability of the nutrients makes difficult a dosed application into soil. The soluble salts (mainly as Na+ form) make necessary a controlled use to avoid environmental degradation.

Descoloração de corantes industriais e efluentes têxteis simulados por peroxidase de nabo (Brassica campestre)

The removal of important textile dyes by turnip peroxidase (TNP) was evaluated. The textile effluents besides the residual dyes contain also chemical auxiliaries such as salts, dispersing and wetting agents. The effect of these was evaluated in the removal of the dyes reactive blue 21 and reactive blue 19 by TNP in synthetic effluents. A decrease of the efficency decolorization was observed. The action of the enzyme on colour removal of dye mixture was equivalent to the dyes alone. The chemical demand of oxygen in the effluent after enzymatic treatment had a significant increase in relation to the untreated effluent.

Estudo da emissão por fluorescência de ultravioleta na quantificação de um inibidor de corrosão do tipo sal de amônio quaternário em água

Quaternary ammonium salts are the corrosion inhibitors most frequently used by the oil industry. In this study, the ultraviolet fluorescence technique was evaluated for the analysis of a quaternary ammonium salt in water as a corrosion inhibitor. The comparison with standard salt showed that an alkyl aryl quaternary ammonium salt is the main fluorophore, with emission maxima at 306 and 593 nm. The best instrumental parameters were: width of excitation and emission slits of 10 and 15 nm, respectively, and scan rate of 10 nm min-1. The presence of aromatic compounds and biocides affects the analysis of corrosion inhibitors.

Stability-indicating comparative methods using mekc and lc for determination of olmesartan medoxomil

A stability-indicating method using MEKC was validated for the analysis of olmesartan medoxomil in tablets. Successful separation was achieved using a fused silica capillary (40 cm x 50 µm i.d.); background electrolyte consisted of a combination of 10 mmol L-1 borate buffer and 5 mmol L-1 anionic detergent sodium dodecyl sulfate (95:5; v/v) pH 6.5; hydrodynamic mode at 50 mBar for 5 s; 25 kV separation voltage at 25 ºC; and column temperature 25 ºC with detection at 257 nm. The proposed method, validated following ICH guidelines, was applied to the determination of this antihypertensive with good results compared with an LC method.

Síntese e caracterização de hidrogéis compósitos a partir de copolímeros acrilamida-acrilato e caulim: efeito da constituição de diferentes caulins do nordeste brasileiro

Superabsorbent hydrogels based on poly (acrylamide-co-acrylate) and different kaolins, were prepared by free-radical aqueous copolymerization. FTIR and WAXS techniques were employed for characterization of a series of hydrogels, obtained by varying the percentage of clay, crosslinking and constitution of kaolin. The water absorbency at equilibrium (Weq) decreased with increasing clay content and the amount of crosslinking agent. Superabsorbent hydrogel (Weq > 1084 g H2O/g gel) was obtained as 10 wt% of white kaolin and 0.05 mol% of crosslinking agent were used. The hydrogel proved sensitive to pH variation and the presence of salts.

Syntheses, characterization and antifungal activity of tris(1,10-phenanthroline)iron(ii) bis(n-r-sulfonyldithiocarbimate)zincate(ii)

Four new compounds with the general formula [Fe(phen)3][Zn(RSO2N=CS2)2], where phen = 1,10-phenanthroline, R = 4-FC6H4 (1), 4-ClC6H4 (2), 4-BrC6H4 (3) and 4-IC6H4 (4), respectively, were obtained by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO2N=CS2K2) and tris(1,10-phenanthroline)iron(II) sulfate, with zinc(II) acetate dihydrate in dimethylformamide. The elemental analyses and the IR data were consistent with the formation of the expected complexes salts. The ¹H and 13C NMR spectra showed the signals for the cationic iron(II) complex and dithiocarbimate moieties. The molar conductance data were consistent with the 1:1 cation:anion complexes in 1-4. The antifungal activities of the compounds were tested in vitro against Candida albicans, Candida tropicalis and Colletotrichum gloeosporioides.

Dft theoretical study of energetic nitrogen-rich C4N6H8-n(NO2)n derivatives

Density functional theory (DFT) calculations at the B3LYP/6-31G** theoretical level were performed for a series of guanidine-fused bicyclic skeleton derivatives C4N6H8-n(NO2)n (n = 1 - 6). The heats of formation (HOFs) were calculated by isodesmic reactions, and the detonation properties were evaluated using the Kamlet - Jacobs equations. The bond dissociation energies were also analyzed to investigate the thermal stability and sensitivity of the compounds. The results show that all of the derivatives have high positive HOFs, compound G has the highest theoretical density, and compound F1 has the highest detonation velocity and detonation pressure. Considering both the detonation properties and thermal stabilities, compounds D1 and D4 (3 nitro substituents), E1 - E6 (4 nitro substituents), and G (6 nitro substituents) can be regarded as potential candidates for high-energy density materials.

Influencia de variables de formulación en la viscosidad de emulsiones de surfactante aniónico-aceite-agua

Phase transition and viscosity behavior of emulsified systems were studied after modifying their physicochemical formulation. Effects of concentration and nature of salts and n-alcohols, and water/oil relation on the rheological properties of emulsions were also studied. Pre-equilibrated systems were emulsified according to an agitation procedure, and the viscosity (cP) was measured at different shear rates ranging from 1 to 300 s-1. The phase behavior, as well as the emulsion type based on electrolytic conductivity, was observed. Several interpretations of the flow and viscosity curves of emulsions were made through the estimation of rheological parameters such as consistency index "k" and behavior index "n".

Avaliação da lixiviação do cádmio e níquel provenientes da degradação de baterias níquel-cádmio em uma coluna de solo

Spent nickel-cadmium (Ni-Cd) batteries and salts of nickel and cadmium were placed in two different columns of soil for a period of two years. A leaching solution was passed through them at ambient temperature in this period. The behavior of metals in each column was then evaluated. Under the conditions of the experiment, cadmium and nickel demonstrated the potential to contaminate and affect the natural cycles of soil. The disposal of Ni-Cd batteries directly to the soil also increased the concentration of nickel (349 mg kg-1) and cadmium (2890 mg kg-1), sometimes exceeding the intervention values defined in CONAMA resolution 420/09.