Digestion-homogenation

Digester Control For control purposes at constant sulfidity and alkah charge, the deligniftcation rate is treated as a homogeneous reaction, which is first order with respect to the lignin, % remaining in the wood, —dL jdt = kL. The influence of time, t, and temperature, T (Kelvin), has been incorporated into one term, called the JT-factor (33). 

On homogenization, the lysate may drastically increase in viscosity due to DNA release. This can be ameliorated to some extent using multiple passes to reduce the viscosity. Alternatively, precipitants or nucleic acid digesting enzymes can be used to remove these viscosity-enhancing contaminants. 

Nitric Acid and Organic Substances. Mixts of perchloric and nitric ac are frequently used to digest (render w sol) organic materials such as animal and vegetable oils, milk, homogenized animal tissues, etc. If the mixts are heated too... 

For most of the methods mentioned above the method uncertainty - important for the expression of material homogeneity, better inhomogeneity - is influenced by different analytical steps such as digestion, and/or extraction, derivatization, separation etc., that are often required to achieve the final result. This consequently increases the method uncertainty. 

This involves a chemical change. It is required that any decomposition procedure should alter the original environment of the sample into a digest, i.e. a solution in which the analyte is distributed homogeneously. More specific conditions set to a decomposition technique are [4] ... 

High-temperature/low-pressure inorganic digestions are an area of application that has benefited from recent advances in vessel and sensor design. The inert properties of Teflon and its resistance to acid attack make it the material of choice for microwave pressure-vessel construction. Improved commercial systems offer additional safety precautions and improved facilities for pressure and/or temperature control. Also, the distribution of microwave radiation inside the oven cavity is fairly homogeneous. Low-pressure systems allow decomposition temperatures of about 180 °C. However, for many matrices, such temperatures are not sufficient to guarantee the complete ashing of thermoresistant sample components. 

Based on their microwave digestion system, Milestone offers the MicroSYNTH labstation (also known as ETHOS series) multimode instrument (Fig. 3.4 and Table 3.1), which is available with various accessories. Two magnetrons deliver 1000 W microwave output power and a patented pyramid-shaped microwave diffuser ensures homogeneous microwave distribution within the cavity [12]. 

HCI-HNOj. Cold digest 0.5 g sample In a test tube with 1.5 ml of cone. HNO, until reaction subsides. Further oxidize the sample In a hot water bath at95°C until brown fumes almost disappear. Remove samples and cool, then add 1.5 ml of cone. HCI and mix. Place the samples in a heated shaker block at 95° C for an hour. Make up to 10 ml volume with 5% diluted HCI and homogenize the solution in a shaker. 

Having as necessary, dried, homogenized or comminuted the samples, they must now be digested in a suitable reagent to extract elements in a suitable form for chemical analysis. In many organizations we have reached the point where the analyses pass from the hands of the person who took the sample to those of the analytical chemist. In the author s experience, however, it must be emphasized that to ensure best-quality results the whole procedure from, for example, statistically sampling a sediment to the final chemical analysis, should be handled by the same person. 

The tissue or cell sample is firstly homogenized in a buffer containing a detergent such as Triton X-100 and sodium deodecyl sulphate (SDS), which disrupts the cell and dissociates DNA-protein complexes. Protein and RNA are then removed by sequential incubations with a proteolytic enzyme (usually proteinase K) and ribonuclease. Finally the DNA is extracted into ethanol. Ethanol only precipitates long chain nucleic acids and so leaves the single nucleotides from RNA digestion in the aqueous layer. 

The systematic characterization of secondary protein modifications is different from sequencing a protein. For a systematic analysis of protein modifications, the complete protein sequence should be covered by the investigation. This is difficult to achieve since the enzymatic digestion of a protein is not homogeneous. The sequence coverage depends on the nature of the protein, its quantity, and the enzyme used. Typical... 

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