Este trabalho descreve o desenvolvimento de uma metodologia para a determinação de atrazina em solução de solo, utilizando Voltametria de Onda Quadrada em condições de Fluxo Contínuo, empregando o eletrodo de gota pendente de mercúrio. Para uma freqüência de 350 Hz e vazão de 0,47 mL min, obteve-se a maior relação sinal/ruído, sendo que a curva analítica obtida em solução de solo na presença de...

To characterize organic nitrogen present in cattle manure compost, a hot-water extract of the compost along with an acid-insoluble (humic acid-like) fraction either treated with alkali or laccase or untreated were separated by size-exclusion high-performance liquid chromatography (SE-HPLC). Nitrogen was then detected by chemiluminescent nitrogen detection (CLND), and humic acid-like substances ...

Neste trabalho, um eletrodo de polipirrol (PPy) foi utilizado como detector eletroquímico potenciométrico em um sistema de injeção em fluxo para a determinação de sulfametoxazol em formulações farmacêuticas. O eletrodo PPy foi preparado por voltametria cíclica em solução de acetonitrila. Uma relação linear foi observada no intervalo de concentração de 2,5 × 10 a 1,25 × 10 mol L com um coeficien...

Three month old Thunbergia alata were exposed for 13 days to 10 μM selenite to determine the biotransformation of selenite in their roots. Selenium in formic acid extracts (80 ± 3%) was present as selenopeptides with Se-S bonds and selenium-PC complexes (selenocysteinyl-2-3-dihydroxypropionyl-glutathione, seleno-phytochelatin2, seleno-di-glutathione). An analytical method using HPLC-ICPMS to de...

specific elements (cr, al, ca, and si) and loss on ignition (loi) were used for semi-quantitative determination of the normative mineralogical composition of naturally occurring chromium ores in ophiolite complexes. by far the occurring ore minerals are complex both from the mineralogical and chemical viewpoints. the secondary minerals serpentine and cr-containing chlorite (kaemmererite) form n...

The early interest in selenium (Se) focused on its toxicity, but since 1957 it has been recognized as an essential dietary element. The diet is the major Se source and approximately 80% of dietary Se is absorbed, depending on the type of food consumed. In several regions of the world, the content of Se in diets has been estimated as insufficient. The dietary requirement for Se for most species ...

Changes in the physicochemical properties and structure of proteins derived from two malt varieties (Baudin and Guangmai) during wort boiling were investigated by differential scanning calorimetry, SDS-PAGE, two-dimensional electrophoresis, gel filtration chromatography and circular dichroism spectroscopy. The results showed that both protein content and amino acid composition changed only slig...