68 resultados para Tracer gas method
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Direct immersion SPME-GC-MS-MS was used for the analysis of steroids in water at part-per-trillion(ppt) and lower concentrations. The method was validated and extended to real sample analysis. The method were linear from 0.01 to 5 ng/ml with precision less than 10% relative standard deviation for a steroid mixture at 1 ng/ml. Limit of quantitation and limit of detection was found to be 200- 1200 pg/L and 30-200 pg/L respectively and recoveries ranged from 88-103 %. To understand the extraction efficiency of the fiber, a depletion study was performed. The fiber/ sample partition coefficients for the steroids were determined to be 1.0 x 104 to 1.5 x 104 . The extraction was performed without derivatization or the use of an internal standard. SPMEGC-MS-MS effectively demonstrated ultra-trace level detection of steroids in water.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Quality is a variable concept, which involves many factors, depending on the consumer market. In meat production, the concern with environmental aspects, animal welfare and the health and safety of workers is increasing. This work studied the effect of controlled atmosphere stunning of broilers on meat features and biochemical parameters for stress. Cobb broilers were stunned by electrical stunning and by controlled atmosphere with 70% CO2 and 70% CO2 + 30% Argon. After stunning, serum levels of glucose, lactate and corticosterone were compared with those of broilers at rest, immediately before transportation and slaughter and after 12 h of feed withdrawal (control group). At slaughter, blood volume drained during bleeding was not different for the stunning methods tested, ranging from 3.3 to 3.4% birds weight. This finding was important to demonstrate that gas stunning was not responsible for the animals′ death. Final pH in breast (6.1 to 6.2) and thigh (6.3 to 6.5) also did not vary among the different stunning methods (P > 0.05). Lightness (L = 60.55) and redness (a = +8.94) values found for breasts from electrical stunning showed that they were darker and redder (P < 0.05), probably due to changes in blood pressure. Glucose and corticosterone levels were not different between gas stunned birds (302.45 to 315.7 mg/dl and 55.71 to 72.49 ng/ml respectively) and birds at rest (305.95 mg/dl and 50.65 ng/ml) (P > 0.05). These stress indicators were higher (337.65 mg/dl for glucose and 104.13 ng/ml for costicosterone) when electrical stunning was used (P < 0.05). Lactate concentrations were lower (5.4 mmol/l) for birds at rest (P < 0.05) but not different for all stunning methods tested (7.3 to 8.1 mmol/l; P > 0.05). These results show that serum glucose may be used as a stress indicator in birds, with the advantage of being a quick and cheap biochemical test. Gas stunning favored birds′ management during slaughter and so reduced workers′ effort and injury hazard and the amount of feces and dust in the room. To make this method available for a large scale process, adjustments in equipments will be necessary to avoid delays in the processing line.
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This paper has the objective of monitoring the biological activity of composting process of sewage sludge, sugarcane bagasse and ground coffee in a hermetic rotary reactor using the respirometric method in laboratory scale, in order to obtain parameters and system design for large scale projects. Another particularity of this study is the use of a hermetic reactor with gas purging cycles. Purging was performed when the percentage of oxygen reached less than 5%, thus eliminating the gaseous mixture (with elevated CO2 ratio) and the introduction of environmental air with around 21% of O2, successively until the compost was stabilized. The average purge intervals obtained were 29 h and 2 min with reactor rotation frequency of 15 min. The time of the compost stabilization was optimized in 60% if compared to the 90 days in the traditional method. The results obtained can be used to design the process in industrial scale using a simple O2 gas analyzer.