Homogeneous drying

A 10-g sample of the homogenized dry sample is soaked in 20 mL of distilled water for 2 h. After adding 100 mL of acetone to the soaked sample and shaking vigorously on a mechanical shaker for 30 min, the extract is filtered. After the addition of a further 100 mL of acetone, the sample homogenate is shaken as before and the acetone extract is filtered. The filtrates are combined and acetone is removed with a rotary evaporator. " ... 

In matrix solid-phase dispersion (MSPD) the sample is mixed with a suitable powdered solid-phase until a homogeneous dry, free flowing powder is obtained with the sample dispersed over the entire material. A wide variety of solid-phase materials can be used, but for the non-ionic surfactants usually a reversed-phase C18 type of sorbent is applied. The mixture is subsequently (usually dry) packed into a glass column. Next, the analytes of interest are eluted with a suitable solvent or solvent mixture. The competition between reversed-phase hydrophobic chains in the dispersed solid-phase and the solvents results in separation of lipids from analytes. Separation of analytes and interfering substances can also be achieved if polarity differences are present. The MSPD technique has been proven to be successful for a variety of matrices and a wide range of compounds [43], thanks to its sequential extraction matrices analysed include fish tissues [44,45] as well as other diverse materials [46,47]. 

Vegetation Sample dried and homogenized dry and wet ashing ICP-MS (total uranium) 0.1 pg/L in final solution No data Boomer and Powell 1987... 

S194 Thompson, S.G. and Boguslaski, R.C. (1987). Homogeneous dry reagent immunoassay strips for the determination of therapeutic drugs in human serum or plasma. J. Clin. Lab. Anal. 1, 293-299. 

Prior to analysis, solid samples are usually homogenized, dried or freeze-dried and ground with a mill to obtain particles with a diameter of less than 1 mm or 0.2 mm. Sometimes, surrogates are added before the extraction process. 

Nowadays, iodine is measured using inductively coupled plasma mass spectrometry (ICP-MS) and energy-dispersive X-ray fluorescence analysis of iodine (EDXRF) (Zaichick and Zaichick 1999). The detection limit of iodine is 3 Jigg for 30-minute measurements of 10-15 mg specimens of fresh tissues, and 10-minute measurements of40- 60 specimens of homogenized dry tissues. 

Solid tissues must be homogenized, dried, ashed, and/or dissolved to produce a liquid sample prior to GF-/ AS analysis. Bone samples for determination are washed free of marrow by a strong stream of distilled water. Any existing fat or muscle is scraped with an aluminium-free obsidian scapel or blade found to be aluminium-free. The bone sample can then be processed by several methods to obtain a solution for injection into the... 

The rate increases up to the equilibrium temperature at the surface, and then it remains constant. During this step, the temperature increases. With time, drying proceeds to the inner cake, and the rate as well as rate mass transfer decreases significantly with increasing temperature till the final temperature. The heat transfer rate is important to obtain a homogenous drying. In the drying processes, usually the rate is of the order of 10°C/min. 

Two other methods of drying are mentioned in the literature, but due to technical constraints, they are not widely appKed. Microwave heating provides a homogeneous drying of large systems [45-47]. Freeze drying, in which water is sublimated at temperatures below 0°C and under low pressure, has been applied to powders and small volumes of materials but also to monoliths [47-49]. In this case, the transport of dissolved species is blocked by the transformation of Kquid water into ice. 

Hence, a faster and more homogeneous drying resulting in a more uniform distribution of residual moisture due to enhanced mass transfer, especially in larger pieces, might be more beneficial with regards to product quality and shelf stability. 

Soil samples were collected at six different locations at IPEN, using a PVC pipe with a diameter of 7.2 cm and a depth of 15 cm, after cleaning the surface manually. The quantity collected was about 500 g, and each sampling point was analyzed in triplicate. The soil samples were homogenized, dried to constant mass and passed through a sieve of 250 gm. 

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