Quantitative response, method

This method is easy to use and easier to calculate than EVOP. It can easily be used with a qualitative or quantitative response. The only decision that needs to be... 

The most common type of qualitative analysis is related to a binary response, with a presence-absence , yes-no or lower than-greater than answer to a main assumption, as for example is the concentration lower than a threshold value This method is interesting for the detection of unknown pollutants and can be easily carried out with screening procedures coupling real qualitative analysis with semi-quantitative responses. 

Most frequently, the design results, or more specifically the factor effects, are analyzed graphically and/or statistically, to decide on method robustness. A method is considered robust when no significant effects are found on responses describing the quantitative aspects. When significant effects are found on quantitative responses, non-significance intervals for the significant quantitative factors can be defined, to obtain a robust response. However, no case studies were found in CE where such intervals actually were determined. 

The method can be robust concerning its quantitative aspect, but non-robust regarding one or more qualitative aspects, i.e., significant effects are found on responses, such as, resolution. Then SST limits can be mathematically or experimentally derived, based on the results of the robustness test. These SST limits correspond to the interval in which a qualitative response is allowed to vary, to still obtain a quantitatively robust method. 

Two Aroclor 1260 standards and A2) were included in these analyses. One standard was from the Columbia National Fisheries Research Laboratory, and the other from the Patuxent Wildlife Research Center (U.S. Fish and Wildlife Service, Laurel, MD.) A difference in the concentration of one constituent of about 30% was responsible for the small difference observed between the two Aroclor 1260 standards (Figure 5.) Use of a quantitative chemometric method to describe compositional residue differences measured in environmental samples may prove helpful in correlating residue profiles and concentrations with observed biological effects, such as decreased survival of young birds. 

This approach is only applicable for methods where SDbl can be estimated from replicate analysis of blank samples. It is therefore not applicable for most quantitative chromatographic methods, as here the response is usually measured in terms of peak area units, which can of course not be measured in a blank sample analysed with a selective method. 

During method optimization, initially qualitative responses, related to the quality of the separation, are considered. On the other hand, during robustness testing, first quantitative responses are studied. Nevertheless, all types of responses can be evaluated during both method optimization and robustness testing. 

During robustness testing, in a first instance, the considered responses usually represent quantitative aspects of the method (5,16). An analytical method is considered robust if no significant effects are found on the response(s) describing the quantitative aspect of the method. Although during method optimization usually quantitative responses are initially not considered, they can, however, be studied. 

Cytotoxicity of extracts was determined by MTT Cell Proliferation Assay [13], a quantitative, convenient method for evaluating a cell population s response to external factors, whether it be an increase in cell growth, no effect, or a decrease in growth due to necrosis or apoptosis. 

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