Assays experimental equipment

The standard error of slope is a suitable numerical parameter for the evaluation of linearity. It measures the deviation of the experimental values from the regression line and thus represents a performance parameter with respect to the precision of the regression. Expressed in percent (relative standard error of slope), it is comparable to the RSD obtained in precision studies in the given concentration range (e.g., 10% -20% RSD at the QL, l%-2% for assay). Therefore, this parameter is better suited for evaluation purposes than the residual sum of squares and the residual standard deviation, which are also measures of the deviation between the experimental data and the regression, but they depend on the absolute magnitude of the signal values and are difficult to compare with results from other equipment or with other procedures. 

Theory alone, however, can never be the basis for selection of a filter. Filtration belongs to the physical sciences, and thus conclusions must be based on experimental assay. It is, however, helpful in understanding why a slurry is more suitable for one design of filtration equipment than another. Methods of optimization in the field can also be predicted by having a background in the theory. 

Availability and choice of instrumentation and how use of different equipment could affect assay performance need to be discussed. Definitions of experimental and storage conditions, reagent sources and quality, and lab personnel experiences should be discussed early on. This also applies to the process of assigning expiry dates, assessment of reagent stability, reagent handling, and shipping processes. 

Methods of choice. The prevailing techniques used by discovery chemists to detect impurities are standard experimental methods chosen for three reasons. They are general and rapid—taking 20 minutes to 3 days—and some of them afford structural knowledge as a bonus. The rapidity of some purity assays depends partly on an open instrument policy and on instruments sufficient to meet demand. In companies that employ specialists to operate analytical equipment, throughput depends on adequate staffing. Many fipcos offer to discovery chemists both open instruments and well-staffed analytical departments. 

The resemblance of the equipment of eighteenth-century chemical laboratories with that used at certain artisanal workplaces accorded with the fact that most of chemists types of experimental techniques corresponded with artisanal operations, in particular those of apothecaries, assayers, and distillers. Dissolutions, distillations,... 

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