Concentration factors affecting method selection

RMC can be selectively extracted into butyl acetate. Concentration coefficient 50 was achieved. Factors affecting accuracy and reproducibility of the proposed method were investigated. Method is simple and fast. Detection limit is 0,3 p.g/1 for P(V). 

Several studies have employed chemometric designs in CZE method development. In most cases, central composite designs were selected with background electrolyte pH and concentration as well as buffer additives such as methanol as experimental factors and separation selectivity or peak resolution of one or more critical analyte pairs as responses. For example, method development and optimization employing a three-factor central composite design was performed for the analysis of related compounds of the tetracychne antibiotics doxycycline (17) and metacychne (18). The separation selectivity between three critical pairs of analytes were selected as responses in the case of doxycycline while four critical pairs served as responses in the case of metacychne. In both studies, the data were htted to a partial least square (PLS) model. The factors buffer pH and methanol concentration proved to affect the separation selectivity of the respective critical pairs differently so that the overall optimized methods represented a compromise for each individual response. Both methods were subsequently validated and applied to commercial samples. 

Table 9 presents information on the corrosion resistance of some common metals, nonmetals, and gasket materials. Table 10 presents similar information for various types of plastics. These tables can be used as an aid in choosing materials of construction, but no single table can take into account all the factors that can affect corrosion. Temperature level, concentration of the corrosive agent, presence of impurities, physical methods of operation, and slight alterations in the composition of the constructional material can affect the degree of corrosion resistance. The final selection of a material of construction,... 

Kee and Durning (1990) reviewed two principal methods of measuring yield stresses dynamic and static methods. One example of the dynamic method is the extrapolation from the flow curve. Equation (4) is often used to determine the yield stress of gum solutions. Table VIII lists the examples of yield stress of several selected food commodities measured from different methods. It is noted that for the same food product, different methods have different yield stress value. In addition to the measuring method, the embedded factor—the composition of food products—also needs to be emphasized. For instance, in mayonnaise, the concentration of oil and xanthan gum significantly affected the yield stress since it increased from... 

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