Qualitative factors, method

Qualitative HPLC methods, using area percent, are used to monitor the disappearance of starting material and the formation of byproduct. Without the inclusion of an internal standard and the calculation of response factors, it is not possible to establish with certainty whether all of the starting material can be accounted for. An internal standard must be stable in the reaction mixture, must not co-elute with any of the components, and must be stable in the mobile phase. Ideally, the internal standard has a retention time about half that of the total analysis time. Internal standardization is extremely useful for kinetic studies. Added to the reaction vessel, samples that are withdrawn at various times will contain identical concentrations of internal standard, and chromatograms can be directly compared or adjusted to identical scales to correct for variation in injection volume. 

The selected factors are either mixture-related, quantitative (continuous), or qualitative (discrete).A mixture-related factor is, for instance, the fraction organic solvent in the buffer system. Examples of quantitative factors are the electrolyte concentration, the buffer pH, the capillary temperature, and the voltage, and of qualitative factors the manufacturer or the batch number of a reagent, solvent, or capillary. Sample concentration (see Table 1) is a factor sometimes included. However, the aim of the method tested is to determine this concentration through the measured signal, from a calibration procedure. Thus, one evaluates the influence of the sample concentration on the sample concentration, which we do not consider a good idea. 

Qualitative factors are also frequently considered in a robustness test. " For CE methods, factors such as the batch or manufacturer of the capillary, reagent or solvent can be selected. When evaluating the influence of such qualitative factor, the analyst should be aware that the estimated effect is only valid or representative for the examined discrete levels and not for any other level of that factor, and certainly not for the whole population. For example, when examining two capillaries X and Y, the estimated effect only allows drawing conclusions about these two capillaries and not about other capillaries available on the market. Such approach allows evaluating whether capillary Y is an alternative for capillary X, used, for instance, to develop the method. 

The factors in Table 3 were selected from a non-aqueous chiral separation method for timolol. One qualitative factor (1), i.e., the type of CE equipment, was examined. Two HPCE systems, A and B, with different software versions for equipment control, data acquisition, and handling were compared. Six quantitative factors ((2) till (7)), for which the extreme levels usually were situated symmetrically around the nominal, also were... 

In this chapter, the possibilities to set up and treat the results of a robustness test were reviewed (Sections I-VIII). Robusmess usually is verified using two-level screening designs, such as FF and PB designs. These designs allow examining the effects of several mixmre-related, quantitative, and qualitative factors, on one or several responses, describing either quantitative and/or qualitative aspects of the analytical method. 

The above is not a complete statement of the theory of matter of Aristotle, but will, it is hoped, give an idea of the elaborateness and complexity of the Aristotelian concept, and serve to illustrate how far removed was his method of developing the theory from the inductive methods of modern science. The concept of the four elements as qualitative factors in the constitution of other bodies, with their inherent forces of heat, cold, moist, dry, became accepted by later centuries as basic truth. His notion of a fifth element, variously interpreted, also held a place in the thought of later times, but his more complex notions of the nature of the elements and matter had little influence on the later development of natural philosophy. 

Due to the advantages and disadvantages of the method of random balance, which have been mentioned in this section, a demonstration of efficiency of the method will be given in this example on an artificially constructed problem and where we know, in advance, the effects that should be screened. It will also be shown that, generally speaking, the method of random balance with more than two levels of factor variation has no advantage. A demand for more than two levels is justified only in cases with qualitative factors. 

We can easily quantify measurement error due to existence of a well-developed approach to analytical methods and laboratory QC protocols. Statistically expressed accuracy and precision of an analytical method are the primary indicators of measurement error. However, no matter how accurate and precise the analysis may be, qualitative factors, such as errors in data interpretation, sample management, and analytical methodology, will increase the overall analytical error or even render results unusable. These qualitative laboratory errors that are usually made due to negligence or lack of information may arise from any of the following actions ... 

Counting polymorphs and solvatomorphs, delavirdine mesylate has been found in 12 different crystal forms, therefore presenting considerable difficulty in the determination of phase composition.63 Only through the combination of factor analysis with the quantitative IR technique could one develop a method useable in the characterization of research and production lots. The composition of drug lots consisting of mixtures of forms was identified through qualitative factor analysis, and quantitated using principal component analysis. Calibration models were developed for the determination of Form-VIII or Form-XH in Form-XI, and a standard error of prediction of 2.0% of either form was reported, with detection limits of 3-5%. 

Optimum conditions. However, modeling a qualitative factor has no meaning because only discrete levels are possible and no intermediate values occur. Therefore, only mixture-related and quantitative factors are examined in the optimization step. Sequential optimization methods select successive experiments in the factor domain, which implies that again only mixture-related and quantitative factors can be examined. 

Note that 3 and X4 are qualitative factors and their values are limited to 1. An optimization method that could distinguish between discrete and continuous variables and which would thus only search the space of permitted values of the qualitative, or discrete quantitative variables, would be preferred. It can also be seen that the maximum desirability, on the edge of the square defined by X X2] at 1, is actually just outside the cylindrical experimental domain. The optimum should, strictly speaking, be displaced very slightly to lie on the edge of the design space. 

There are minor differences between the two decision processes. The SSCl is determined in a more qualitative way by using two factors, i.e. hazard severity and software autonomy. The SIL should he determined in a quantitative probabilistic way by computing the risks of the system and comparing with accepted risk levels. Thus the necessary risk reduction is determined which in tun determines the rehahhity requirement for the safety function. Risk graphs (see section 2.2) and risk maps are rather considered as qualitative estimation methods by lEC 61508. Finally we mention that the AOP 52 presents in chapter 11 in total 6 case studies where 3 are taken fi om the ammunition domain. Such specific examples are not available in the lEC 61508. 

Polymers with differing chemical structures will usually have a different coil volume in solution and produce a displaced calibration curve. Various procedures have been proposed to overcome this problem and to produce a Universal calibration curve. These include the g factor method [16], the use of hydrodynamic volume [17], and unperturbed dimensions [18]. The use of broad-molecular-mass distribution polymers as calibration standards has also been employed. These procedures are discussed more fully in Chapter 3. They are only important if accurate relative molecular masses are required if the technique is being used simply for qualitative purposes, these procedures are not important. 

A number of experiential distinctions are especially pronounced when comparing direct and bricks-and-mortar channels. These include visual and tactile interaction with the product, the method of obtaining product information (e.g., face to face, over a phone line, or through a computer screen), the delay between purchase and receipt, and even the crowds that often define bricks-and-mortar shopping (which can either be a positive or a negative depending on individual preferences). Naturally, these types of qualitative factors have been difficult to model in any detail. 

The analytic hierarchy process (AHP), developed by Saaty (1980), is a multicriteria decision making method for ranking alternatives. Using AHP, the DM can assess not only quantitative but also various qualitative factors, such as financial stability, feeling of trust, etc. in the supplier selection process. The buyer establishes a set of evaluation criteria and AHP uses these criteria to rank the different suppliers. AHP can enable the DM to represent the interaction of multiple factors in complex and unstructured situations. AHP does not require the scaling of criteria values. 

The qualitative ninhydrin method of Kaiser et al. (1970) has been worked into a quantitative method by Chou et al. (1971). A known amount of the resin is treated with the ninhydrin reagent and the absorption of the supernatant is measured after dilution, at 570 nm, with relation to a ninhydrin blank. Bayern/ al. (1976), however, noticed that the method does not give absolute values since a correction factor, dependent on the relevant amino acid and its position in the peptide chain, is needed. 

Many quantitative methods are available to assist managers as they select projects that will add value to the company and to their shareholders. Although quantitative methods are helpful, it is important to note that qualitative factors such as corporate social responsibility and sustainability efforts compliment project selection decisions. In... 

Thus it would appear that a moderate reduction of the maternal food intake does not materially influence the fetus. However, recent studies in man based on a better knowledge of nutritional requirements and evaluated by statistical methods have shed new light on the influence of maternal diet on fetal development. They have shomi that quantitative and qualitative factors of the maternal diet affect the condition of the infant at birth without causing inanition of the mother. These studies will be discussed later in a special section (p. 91). 

In addition to qualitative identification of the elements present, XRF can be used to determine quantitative elemental compositions and layer thicknesses of thin films. In quantitative analysis the observed intensities must be corrected for various factors, including the spectral intensity distribution of the incident X rays, fluorescent yields, matrix enhancements and absorptions, etc. Two general methods used for making these corrections are the empirical parameters method and the fimdamen-tal parameters methods. 

---