Contents 3 Preparative methodology

The selection of sample preparation methodology is highly dependent on both analyte and sample (matrix) characteristics. To approach the matrices in the same cost-effective ( multi ) way as analytes, food, commodities, and in relation to that also sample preparation methods, are primarily classified based on the fat content the limit between fatty and nonfatty food matrices being usually set at 2%. 

Several of the methods mentioned earlier for the determination of the uranium content in soil are also suitable for assaying the uranium content in plants. However, there are two major differences the uranium concentration in plants is usually significantly lower than in soil and the fraction of organic matter and the moisture content in plants are much higher than in soil. These two factors dictate somewhat different sample preparation methodologies and more sensitive analytical devices are preferred as shown in the following examples. Some of the review articles mentioned earlier also discuss the uramum content, uptake (transfer factor), and distribution in plants (Zavodska et al. 2008 Mitchell et al. 2013). One of the most comprehensive sources listing the uranium content in many different types of plants is the Canadian report mentioned earlier (Environment 2007). An additional important source can be found in the report published by the IAEA (IAEA 2010). 

Nanopowders were sintered at 1100 C to produce porous pellets. The porosity, particle size and microstructure of LSM sintered bodies are strongly dependent on the preparation methodology. The samples synthesized by combustion and citrate methods presented smaller particle sizes and higher porosity after sintering than those derived fiom solid-state synthesis. The electrical conductivity, measm-ed by two probe technique, increases with temperature, as expected in a semiconducting behavior, and increases with increasing Sr content. 

Data from a study conducted by the Japanese Bioassay Research Center (JBRC) (45) are reviewed here. Data summary tables and summarized methodological details are available. Groups of 50 male and female rats and mice were administered 0, 400, 2000, or 10,000 ppm vinyl acetate for up to 104 weeks. The stock solution (98% pure vinyl acetate) contained impurities of hydroquinone (5 ppm), acetic acid, and water. Except for hydroquinone, the concentrations of the impurities were not specified. Vinyl acetate drinking water solutions were prepared twice a week. The solutions were kept in airtight containers and analyzed for vinyl acetate content before and after... 

Cichoric acid is believed to contribute to the immunostimulatory activity, but the compound tends to decompose through enzymatic degradation during extractions (Bauer, 1997) thus, the variability in cichoric acid levels found by many researchers may be due to the extraction methodology and not to the plant species or origin. Bauer (1999b) evaluated the cichoric acid content of six commercially available expressed juice preparations of E. purpurea. The thermally treated preparations had higher cichoric acid than ethanol-preserved preparations. The inactivation of polyphenol oxidase by heat may account for the difference found between heated and nonheated preparations. 

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