Doehlert designs

Figure 3.15. Doehlert design for two factors, with coded values. The shaded triangle is the generating simplex.

A note is in order here to stress that a special form of experimental designs can be used for optimization. They are known as Doehlert designs, of which several applications are reviewed in Table 2.34. As this chapter is intended at an introductory level, no further details will be give here. 

Doehlert designs and response surface models were developed to evaluate the effects and interactions of flve variables on the extraction of Mn in a flow-injection device. 

An on-line coupling of a flow-injection system with the AAS technique was proposed. The full factorial design was used to ascertain the relevant variables which were then optimised using a Doehlert design (pH and concentration of the complexing agent)... 

FAAS A four-variable Doehlert design was used to optimise a... 

ICP-OES A 5-level Doehlert design provided multivariate insight... 

ETAAS Doehlert designs were used to optimise the temperature... 

Tak, V. et al. Application of Doehlert design in optimizing the determination of degraded products of nerve agents by ion-pair liquid chromatography electrospray ionization tandem mass spectrometry, J. Chromatogr. A. 2007,1161,198-206. 

Fig. 6.16. Doehlert design for Ivvo factors (points / till 7) and demonstration of the sequentiality of the design (additional points 8-10).

The central composite design is most often used, however, there are others whose particular properties make them particularly useful. One of these is the Doehlert design, which is part of a continuous hexagonal network.f It requires slightly fewer experiments than... 

Fig. 6 Doehlert design in three dimensions (factors) showing extension to a new experimental domain.

FIGURE 2.8. Doehlert design for three factors (at least 13 experiments). 

Tropane alkaloids pH, [SDS], [organic modifier] R, T, generated power and current Doehlert design, MLR, RSM hn and peak area precision, linearity, sensitivity, accuracy (63)... 

Mateus, L., Cherkaoui, S., Christen, R, and Veuthey, J.-L. (1998) Use of a Doehlert design in optimizing the analysis of selected tropane alkaloids by micellar electro-kinetic capillary chromatography. / Chromatogr A, 829, 317-325. 

Doehlert design used for significant factors nebulizer pressure, dry gas flow, sheath-liquid flow rate, percentage of 2-propanoI in the sheath liquid. 

TABLE 10.1. Comparison of efficiency of central composite design (CCD), Doehlert design (DM), and Box-Behnken design (BBD) (dted from Reference 31 with permission from Elsevier)... 

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