Teste de TBA aplicado a carnes e derivados: métodos tradicionais, modificados e alternativos

The TBA test is essential to quality control of fat-containing food, being the test most applied to evaluate lipid peroxidation in fishery, meat and poultry products. It estimates malonaldehyde, a secondary oxidation product, by reacting with 2-thiobarbituric acid, forming a coloured complex, measured spectrophotometrically atlambda = 532 nm. Results are expressed as mg malonaldehyde per kg sample or frequently as "TBA value". There are four ways of quantifying it: by lipid extraction, direct heating, distillation or heat-acid extraction. This review intends to point out traditional, modified and alternative TBA test methods, besides enumerating advantages and drawbacks of each one.

Estudo espectroscópico de complexos de Eu3+, Tb3+ E Gd3+ com ligantes derivados de ácidos dicarboxílicos

Complexes of Eu3+, Tb3+ and Gd3+ with dipicolinic acid, chelidamic acid and chelidonic acid have been synthesized in order to study the effect of the substituent groups on the luminescence of the lanthanide complexes. The luminescence of the Eu3+ and Tb3+ complexes was quantified by quantum yield measurements. The complexes of Gd3+ have been used to determine the energies of the triplet states of the ligands. The Tb3+ complex synthesized with dipicolinic acid presented the highest quantum yield due to the energy difference between the triplet state of the dipicolinic acid and the emitting level of the Tb3+ ion.

Síntese e caracterização de novos complexos de platina (II) com ligantes derivados do furano e nitrofurano

Platinum (II) complexes, for example, cisplatin and carboplatin, have been used as chemotherapeutic agents for the treatment of various types of cancer. Several other complexes of this metallic ion are also under clinical evaluation. This work describes the synthesis of five new platinum (II) complexes having furan and 5-nitrofuran derivatives and chloride as ligands. The compounds were characterized by NMR, IR and elemental analysis.

Reações de carbociclização radicalar de orto-iodoaliloxibenzoatos derivados de d-glicose e d-galactose e comparação com as reações de seus análogos benzamidas

Two ortho-iodoallyloxybenzoates, methyl 4-O-allyl-2,3-di-O-benzyl-6-O-(2-iodobenzoyl)- alpha-D-glucopyranoside (3) and methyl 4-O-allyl-2,3-di-O-benzyl-6-O-(2-iodobenzoyl)- alpha-D-galactopyranoside (4) were synthesized in seven conventional steps from methyl alpha-D-glucopyranoside and methyl alpha-D-galactopyranoside, respectively. Bu3SnH-mediated aryl radical cyclization of 3 provided exclusively the hydrogenolysis product 12. The reaction of 4 gave the reduced uncyclized product 13 and only traces of 4A, resulting from 11-endo aryl radical cyclization. In previous papers we described that in similar Bu3SnH-mediated radical reaction of ortho-iodoallyloxybenzamides, analogs of 3 and 4, we obtained macrolactams resulting from 11-endo cyclization. An hypothesis to explain the differences is presented. It was assumed that in the aryl radical formed from iodobenzamides there is a suitable conformation to cyclization, which is stabilized by an intramolecular hydrogen bond.

Seguridad y riesgo de toxicidad de los alimentos: un debate actual

El progreso científico y tecnológico ha tenido muchas consecuencias beneficiosas para la humanidad pero también conlleva riesgos. Un ámbito en el que estos dos aspectos de la cuestión se manifiestan más claramente es el de la alimentación humana. Las posibilidades actuales de la industria alimentaria permiten la obtención de productos cada vez más adaptados a las necesidades y gustos del consumidor No obstante, existe una desconfianza frente a los alimentos transformados que se juzgan, injustamente, como menos seguros que los frescos o naturales. Ciertos escándalos de gran resonancia alimentan esta desconfianza, y no suele tenerse en cuenta que las vacas locas, los pollos con dioxinas o la carne con hormonas, por ejemplo, son problemas de las fases primarias de producción, agrícola y ganadera, y no de la industria alimentaria propiamente dicha. Bajo la perspectiva global de lo que son los alimentos y de lo que conocemos de su composición y funciones en el ser humano, y teniendo en cuenta de que el riesgo cero no existe para ninguna actividad, y por lo tanto tampoco en la alimentación, se puede afirmar que nuestros alimentos nunca han sido tan seguros como en la actualidad, aunque sigue habiendo problemas y en un tema como éste, de evidente implicación sanitaria, toda precaución es poca. En este artículo se discuten las relaciones entre alimentación y riesgo y la percepción social sobre estas relaciones, se describen someramente los componentes tóxicos naturales de los alimentos, la contaminación de los mismos, los problemas de alteración y deterioro, así como la adulteración y el fraude y sus consecuencias. También se aborda la significación de casos actuales que cuestionan la seguridad de los alimentos y el papel del control alimentario, por parte de productores y administraciones para garantizar la calidad y la seguridad de los alimentos.

Eletroanálise de derivados acetaldeído com hidrazina e determinação em amostras de álcool combustível por voltametria de onda quadrada

A square wave voltammetric method is described for the determination of acetaldehyde using the derivatization reaction with hydrazine sulphate, based on the reduction of hydrazone generated as a product that exhibits a single well-defined peak at -1.19V in acetate buffer at pH 5. Calibration graphs were obtained from 1.0 x 10-6 mol L-1 to 10 x 10-6 mol L-1 of acetaldehyde, using a reaction time of 8 min and a hidrazine concentration of 0.02 mol L-1. The detection limit was 2.38 x 10-7 mol L-1. The method was applied satisfactorily to the determination of total aldehyde in fuel ethanol samples without any pre-treatment.

Determinação espectrofotométrica simultânea de cobre e ferro em álcool etílico combustível com reagentes derivados da ferroína

In the present work three ferroin reagents were studied for the simultaneous spectrophotometric determination of iron and copper: 1,10-phenanthroline, 2,2'-bipyridine and 2,4,6-tri(2-pyridyl)-1,3,5-triazine. Effect of pH, conditions, order reagent addition, interferences, amount of reagents, lineal range, sensitivity and stability of each system were compared. The 2,4,6-tri(2-pyridyl)-1,3,5-triazine can be used for determination of iron in the presence of copper with a detection limit of 5 µg L-1 and coefficient of variation of 2.0%; However it was not possible to determine directly copper in the presence of iron with this reagent. 1,10-phenanthroline can be used for simultaneous determination of the metallic ions with detection limits of 7 and 8 mg L-1 and coefficients of variation of 1.8 and 2.3% in the determination of iron and copper, respectively. The results showed also that 2,2'-bipyridine can be used for simultaneous determination of the metallic ions with detection limits of 11 and 32 µg L-1 and coefficients of variation of 1.9 and 2.5% in the determination of iron and copper, respectively. The reagents were used for spectrophotometric determination of iron and copper in ethanol fuel.

Síntese e emprego do ciclometalado [Pd(dmba)(N3)(PPh3)] em processos catalíticos envolvendo a n-carbonilação redutiva de nitroarenos a carbamatos e na síntese de derivados da uréia

This work deals with the use of the cyclometallated compound [Pd(dmba)(N3)(PPh3)] in homogeneous catalytic processes comprising the reductive N-carbonylation of nitrobenzene and p-nitrotoluene to ethyl-phenylcarbamate and ethyl-4-methylphenylcarbamate, respectively. The cyclopalladated compound was also employed in the synthesis of urea derivatives by reacting p-nitrotoluene and m-nitrotoluene, respectively, with p-toluidine and and m-chloroaniline.

Caracterização de amostras petroquímicas e derivados utilizando cromatografia gasosa bidimensional abrangente (GCxGC)

The goal of this article is to discuss the application of comprehensive two-dimensional gas chromatography (GCxGC) to petrochemical samples. The use of GCxGC for petroleum and petroleum derivatives characterization, through group type analysis, or BTEX (benzene, toluene, ethylbenzene, xylenes), total aromatic hydrocarbons, polyaromatic hydrocarbons, sulfur-containing, oxygen-containing, and nitrogen-containing compounds is presented. The capability of GCxGC to provide additional specific chemical information regarding petroleum processing steps, such as dehydrogenation of linear alkanes, the Fischer-Tropsch process, hydrogenation and oligomerization is also described. In addition, GCxGC analyses of petrochemical biomarkers and environmental pollutants derived from petrochemicals are reported.

Quitosana: derivados hidrossolúveis, aplicações farmacêuticas e avanços

Chitin and chitosan are copolymers build from N-acetyl-D-glucosamine and D-glucosamine. The former is widely found in nature and yields the latter on deacetylation. The copolymers are being used for several purposes. Since 1977, when the First International Conference on Chitin and Chitosan was held in Boston, USA, the interest on chitin and chitosan has remarkably increased. This review emphasizes pharmaceutical applications of chitosan and its derivatives, and presents recent advances. Some therapeutical applications of these polymers are also discussed.

Leite e alguns de seus derivados: da antiguidade à atualidade

This work presents a little of the history which marked the development of the dairy industry in Brazil and in the world. It shows problems and solutions related to the preservation of milk. In general, it also describes the traditional manufacture of cheese and applications of membrane technology as an auxiliary tool in the processing of some types of cheese.

Estudo de recuperação de glifosato e AMPA derivados em solo utilizando-se resinas nacionais

In the present paper we studied the recoveries of glyphosate, N-(phosphonomethyl)glycine (GLY) and its major metabolite, (aminomethyl)phosphonic acid (AMPA) in soil using national (Brazilian) ion-exchange resins, derivatization by a mixture of trifluoroacetic anhydride and trifluoroethanol and analyses by GC-MS. The quantification limits were 12 ng.g-1 for both compounds and the methodology showed a range of recuperation from 85 to 94% with coefficients of variation (CV) ranging from 4.07 to 6.91% for GLY. For AMPA, the mean recoveries ranged from 87 to 102% with CVs ranging from 5.81 to 6.99%. Additional studies showed that, due to the instability of the derivatized compounds, they must be analysed keeping constant time between derivatization and analysis, preferably less than 24 h.

Síntese e avaliação da propriedade reguladora de crescimento vegetal de compostos indólicos derivados do safrol

The present work describes the use of piperonal, a derivative of the secondary metabolite safrole, for the synthesis of new 5,6-methylenedioxysubstituted indole carboxylic acids structurally related to the indol-3-yl-acetic acid (AIA, I). The route comprises six steps beginning with piperonal with an overall yield of 19%. Compound IX was tested towards its plant growth regulator properties in bioassays specific for auxine activity. The in vitro assays were performed in a germination chamber and were of two types: root growth in germinated seeds of Lactuca sativa, Cucumbis sativus and Raphanus sativus and peciole biotest using Phaseolus vulgaris.

Sistema de almacén y dispensación robotizada de productos farmacéuticos

Actualmente, las necesidades de mejora en gestión de stocks y la mayor disponibilidad de sistemas automáticos, están haciendo que muchas empresas inviertan en técnicas modernas para almacenamiento y manipulación de productos. Esta inquietud también ha llegado a las farmacias, que de forma lenta pero firme se van apuntando a su robotización. Uno de los principales problemas a los que se enfrentan las farmacias es la pérdida de tiempo en la gestión y búsqueda de medicamentos, provocando situaciones negativas como las esperas, la falta de tiempo para una atención más personalizada y como consecuencia, la pérdida de clientes. Este inconveniente y la necesidad de mejora en la gestión de los stocks han hecho que aparezcan los Sistemas de dispensación automática de productos farmacéuticos. El dispensador automático facilita el trabajo del farmacéutico al automatizar la búsqueda de la medicina requerida, aumentando la dedicación al cliente y reduciendo los tiempos no productivos y las colas. El presente estudio desarrolla un sistema de dispensación automático de fármacos aplicado a farmacias con una rotación de medicamentos media/ baja, valorando tanto su viabilidad técnica como económica. El almacén propuesto es de tipo caótico con sistema de carga, almacenamiento y descarga completamente automáticos. La mayoría de diseños y conceptos expuestos en este trabajo son de desarrollo propio del autor con el único objetivo de la búsqueda de nuevas soluciones para conseguir un sistema de almacenamiento efectivo y de máximo rendimiento.

Síntese de aminoálcoois derivados do D-manitol

Aminoalcohols have found important applications in synthetic and medicinal chemistry, being used as chiral building blocks for the synthesis of many biologically active compounds. This class of compounds has been also used as chiral auxiliaries and ligands in asymmetric synthesis. Due to the importance of aminoalcohols in the treatment of several diseases, such as tuberculosis, the aim of this article is the synthesis and preliminary evaluation against tuberculosis of six aminoalcohols in 5 or 6 steps using D-mannitol as starting material, which is a useful carbohydrate employed in many syntheses.