Response surface methodology method development

Innovations in statistical tools such as multivariate analysis, artificial intelligence, and response surface methodology have enabled rational development of formulations, and such methods allow formulators to identify critical variables without having to test each combination. 

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). 

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. 

Jeong, 1. S., Kwak, B. M., Ahn, J. H., and Jeong, S. H. 2012. Determination of pesticide residues in milk using a QuEChERS-based method developed by response surface methodology. Food Chem. 133 473-481. 

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... 

Electrochemical methods can also be used for obtaining analytical information on porous materials. Voltammetric methods and related techniques have been largely used to acquire information on reaction mechanisms for species in solution phase, whereas impedance techniques have been extensively used in corrosion and metal surface studies. In the past decades, the scope of available methods has been increased by the development of the voltammetry of microparticles (Scholz et al., 1989a,b). This methodology, conceived as the recording of the voltammetric response of a solid material mechanically transferred to the surface of an inert electrode, provides information on the chemical composition, mineralogical composition, and speciation of solids (Scholz and Lange, 1992 Scholz and Meyer, 1994, 1998 ... 

For quantitative measurements of both the interaction forces and the surface topography, the tip shape and the spring constant need to be calibrated. Various approaches to characterize the tip shape are described elsewhere. Concurrently, a series of methodologies induding the added mass methods, unloaded resonant, and reference spring techniques, as well as thermal noise analysis were developed to quantify the spring constant. More recently, new methods have been proposed for calibration of both torsional and normal spring constants with an uncertainty below 10%. " Furthermore, the torsional response of an externally driven cantilever in a viscous medium was analyzed. ... 

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