857 research outputs found
Conversão e balanço energético de sistemas de produção com integração lavoura-pecuária, sob plantio direto.
Modern stationary phases for reversed phase high performance liquid chromatography
This review first discusses the limitations of many of the supports and stationary phases used in reversed phase high performance liquid chromatography and then describes those, developed more recently, that present better stabilities and more versatile selectivities. Emphases will be given to stationary phases that use higher purity silicas, hybrid silicas, monolithic silicas, metallic oxides and mixed oxides as supports and those that have embedded polar groups or contain phenyl or fluoro groups as the stationary phase as well as the phases used for mixed mode or hydrophilic interaction separations. These modern stationary phases facilitate the analysis of complex mixtures.15591568Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Conversão e balanço energético de sistemas de produção com integração lavoura-pecuária (Spilp), sob plantio direto.
bitstream/item/128915/1/ID41957-2010-LVdocumentos96-p71-88.pd
Rendimento de grãos e algumas características agronômicas de soja, em sistemas de produção integração lavoura-pecuária, sob plantio direto.
Rendimento de grãos de trigo de duplo propósito, em sistemas de integração lavoura-pecuária, sob plantio direto.
Wastewater-based epidemiology of cocaine in the Brazilian Federal District : spatial distribution, weekly variation and sample preservation strategies
The distribution of consumed cocaine in the Brazilian Federal District (FD) was estimated
using the wastewater-based epidemiology (WBE) approach. Sewage samples from eight wastewater
treatment plants were analyzed for cocaine (COC) and benzoylecgonine (BE) using solid-phase
extraction followed by liquid chromatography-mass spectrometry. The highest per capita
consumption was noticed for the northern area of the Brazilian Capital (1162 mg day-1 1000 inh‑1)
being 32% higher than the average consumption rate of the investigated region. In this area, a
day-to-day investigation revealed an average cocaine consumption of 1800 mg day-1 1000 inh-1
during the weekend, i.e., more than 50% higher than weekdays. An annual street-grade cocaine
load of about 2 ton was estimated for the FD considering previous information on the actual purity
of seized street drugs as well as consumers between 15 and 64 years old. Sample preservation
strategies were also investigated in order to expand the WBE approach to other Brazilian areas.
Sample acidification to pH 2.0 presented the smallest relative errors for COC (+11%) and BE
(−4%) after a period of three days under typical transport conditions practiced by the Brazilian
national postal service
Propriedades do Skewness da Velocidade Vertical Turbulenta no caso de Convecção Forte: Simulação do Les e Dados Observacionais
Avaliação do efeito de tipos de manejos de solo nos atributos físicos de solo, após seis safras.
A validated NMR approach for MDMA quantification in Ecstasy tablets
In recent years, ecstasy trafficking has grown in complexity and tablets has been commonly sold containing different contents of 3,4-methylenedioxymethamphetamine (MDMA) or even other psychoactive substances. In contrast, identification and quantification of drugs of abuse is still a challenge, once the access to drug standards is very restricted in Brazil. In this work, ecstasy tablets seized by the Brazilian Federal Police have their chemical composition identified and quantified by gas chromatography and quantitative 1H nuclear magnetic resonance based on an internal standard approach (IS-1H-qNMR). Both methods were validated and showed suitable results for the figures of merit. IS-1H-qNMR shows excellent results of accuracy (relative error < 5%) and precision (relative standard deviation (RSD) < 2%). Comparatively, IS-1H-qNMR is more efficient and versatile than gas chromatography to accomplish in a single analysis the identification and quantification of target analytes. Since the method does not require a specific reference material, it is cost effective and provides agility to routine forensic analysis
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