Incurred material

Incurred materials These are materials in which the airalyte of interest may be essentially alien, bnt has been introdnced to the bnlk at some point prior to the material being sampled. The analyte is thus more closely bormd in the matrix than it... 

Samples must be homogeneous and tested for homogeneity, and should be coded at random, including the two or more blind replicates. A blank or negative control, and, if available, reference materials should be provided. Spiked materials are recommended for recovery study, incurred materials for residues study. 

The second aspect of method validation is the experimental work. This typically involves initial experiments with analytical standards to confirm the reliability and repeatability of calibration of the system using only standards. The next step usually involves a series of analytical runs, conducted over several days or weeks, in which one or more analysts prepare calibration curves and analyze replicates of the typical analyte/matrix combinations and concentrations that are to be routinely analyzed using the method. The final phase of validation typically includes several runs in which fortified or incurred materials, again representing typical analyte/matrix combinations and concentrations, are provided blind to the analyst(s). The results are then summarized in a validation report, which again should receive appropriate peer review within the laboratory prior... 

When planning analytical recovery experiments, it is important to compare observed recoveries against known performance. However, absolute recovery using radiolabeled incurred material is rarely an option. This leaves the options of using either matrix-fortified (method matrix-matched or pre-extraction spiking) or matrix-matched (post-extraction spiking) reference materials. In post-extraction spiking, the extract from the analytical sample is spiked with the analyte of interest at a known concentration immediately after extraction. As a result, the extraction efficiency is unknown and therefore there is an additional uncertainty introduced into the analytical procedure. 

If, however, the analytical sample is spiked with a known quantity of analytical standard prior to extraction (pre-extraction spiking), a more accurate assessment of the extraction efficiency is obtained, although the possibility of losses due to tissue-analyte binding cannot be disregarded, and a more accurate appreciation of analytical recovery will be obtained. Comparisons of these spiking methods showed that the latter approach gave acceptable results in the absence of radiolabeled incurred material. ... 

Also, instead of using two separators, a purge can be used (see Fig. 4.2c). Using a purge saves the cost of a separator but incurs raw materials losses and possibly waste treatment and disposal costs. 

The fourth option, shown in Fig. 4.4FEED-IMPURITY separation is expensive. To use a purge, the FEED and IMPURITY must be adjacent to each other in order of volatility (again, assuming distillation as the means of separation). Care should be taken to ensure that the resulting increase in concentration of IMPURITY in the reactor does not have an adverse effect on reactor performance. 

Rather than send the vapor to one of the separation units described above, a purge can be used. This removes the need for a separator but incurs raw material losses. Not only can these material losses be expensive, but they also can create environmental problems. However, another option is to use a combination of a purge with a separator. 

When low boiling ingredients such as ethylene glycol are used, a special provision in the form of a partial condenser is needed to return them to the reactor. Otherwise, not only is the balance of the reactants upset and the raw material cost of the resin increased, but also they become part of the pollutant in the waste water and incur additional water treatment costs. Usually, a vertical reflux condenser or a packed column is used as the partial condenser, which is installed between the reactor and the overhead total condenser, as shown in Figure 3. The temperature in the partial condenser is monitored and maintained to effect a fractionation between water, which is to pass through, and the glycol or other materials, which are to be condensed and returned to the reactor. If the fractionation is poor, and water vapor is also condensed and returned, the reaction is retarded and there is a loss of productivity. As the reaction proceeds toward completion, water evolution slows down, and most of the glycol has combined into the resin stmcture. The temperature in the partial condenser may then be raised to faciUtate the removal of water vapor. 

Revenue expenditure includes the direct material costs and direct labor costs incurred in the manufac ture of a produc t, together with the associated overheads that include maintenance of the plant. Since these expenses are debits, the debit balance for a given accounting period is obtained by adding up the debit balances from each individual expenditure account. Similarly, since revenues from sales and other income are credits, the credit balance for a given accounting period is obtained by adding up the credit balances from each individual income or revenue account. 

The continuously stirred mill can be fed by screw feeders from several material bins siiTuiltaneously, thus blending uniform compositions, without incurring problems of transporting imperfectly blended or agglomerated mixtures. A series of mills may be used with decreasing media size and increasing rotary speed to achieve desired fine-particle size. No additional feed pumps are needed. 

Two main benefits accrue from a systems approach to materials handling and packaging. First, a trade-off of investment and operating costs is made possible nigher costs in some parts of a system become permissible in return for much lower costs in other parts. The net result is usually the lowest overall cost. If this is not the case, the reasons for incurring the higher costs can be identified and justified. The second benefit is that customers are not offended by ill-conceived packages, delivery vehicles, or product characteristics. 

Moisture content is another common and controllable flow factor. Most materials can safely absorb moisture up to a certain point further addition of moisture can cause significant flow problems. Specifications can control the amount of moisture content present in purchased raw materials. Moisture content can be lowered in the plant by including a drying operation in the process line. The costs incurred in drying may be offset by more efficient flow, lower shipping cost, and control of deterioration losses. 

In many cases, this wastewater has environmental implications and incurs treatment costs. In addition, wastewater may wash out valuable unused raw materials from the process areas. It is very important to know how much wastewater is going down the drain, and what that wastewater contains. The wastewater-flows from each imit operation, as well as from the process as a whole, need to be quantified, sampled, and analyzed. 

Filter aids should have low specific surface, since hydraulic resistance results from frictional losses incurred as liquid flows past particle surfaces. Specific surface is inversely proportional to particle size. The rate of particle dispersity and the subsequent difference in specific surface determines the deviations in filter aid quality from one material to another. For example, most of the diatomite species have approximately the same porosity however, the coarser materials experience a smaller hydraulic resistance and have much less specific surface than the finer particle sizes. 

Where, for example, chloride stress-corrosion cracking is a risk the process temperature becomes a critical variable. Thus it may be more economic to lower the process temperature to below 70°C, a practical threshold for chloride stress-corrosion cracking, than to incur the extra expense of using stress-corrosion cracking-resistant materials of construction. 

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