Method development response surface designs

Method development and optimization are started with review of the currently available methods within the company or in literature. Available methods are used as a starting point and evaluated against the method requirements set in the method definition. If necessary the method is optimized or redeveloped in order to fulfill the requirements. DOE tools (response surface design) are preferentially applied to obtain the best optimal conditions in terms of robustness. Application of DOE methodology is not new in chromatography and DOE is frequently applied also for enantiomeric separations in Especially in... 

In the screening phase of method development and in robustness tests, the factors usually are examined at two levels (-1, +1). On the other hand, in the response surface designs, applied in method optimization, the factors are examined at three or more levels, depending on the applied design (see further). 

A.2.3. Example of an Applied Response Surface Design. In the optimization phase of the development of a CE method for the chiral enantio-separation of a nonsteroidal anti-inflammatory drug (28), a circumscribed CCD was performed. The applied symmetrical response surface design is as shown in Table 2.14, with a = 2 f = 1.68. The center point (experiment 15 in Table 2.14) was replicated five times (experiments 15-19). 

If on the other hand we have developed a formulation or process but we wish to predict the response(s) within the experimental domain, then we must use an appropriate design for determining mathematical models for the responses. This and the method used (response surface methodology or RSM) are covered in chapter 5. These 3 subjects are closely related to one another and they form a continuous whole. 

Five factors for hydride generation were studied to develop a method to determine As in gasolines. A central composite design was used to develop the response surface and, thus, optimise the extraction procedure... 

CE also suffers from several weaknesses as an analytical technique (e.g., adsorption of charged species to the capillary wall, presence of Joule heating). Hence, it is important to be able to determine optimal conditions in CE method development (23). Various chemometric-based techniques including multivariate experimental design and response surface methodology have been devised to help optimize the performance of a system (23-26). 

Injection molding processes using Stat-Ease Inc. response surface methods for process optimization are developed with design of experiments (DOE) and a multifactor linear constant (MLC) [10]. 

The model is subjected to an MRE analysis using the response surface based optimisation developed by the authors Munck et al. (2006) and a vertex (also called two level full factorial design of experiments or transformation method) analysis. Each analysis is done at 6 Q -levels(0.0, 0.2,..., 1.0). 

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