. Author manuscript; available in PMC: 2010 Apr 30.

Published in final edited form as: J Chromatogr A. 2008 Dec 6;1216(5):845–856. doi: 10.1016/j.chroma.2008.11.093

Table 3.

Regression coefficient of the coded factors and analysis of variance for the response surface models of chiral resolution (quadratic model) and migration time (2FI model) for the optimization of MEKC factors.

Term	Resolution-BNP		Resolution -BOH		Migration time time^c
	Coefficient	Prob>F^d	Coefficient	Prob>F	Coefficient	Prob>F
Intercept (b₀)	0.74		1.1		10.38
F₁: pH	−0.085	<0.0010	0.11	0.0010	−0.34	0.0022
F₂: [surfactant]	0.13	<0.0010	0.028	0.38	0.60	<0.0010
F₃: [NH₄OAc]	0.013	0.53	0.0087	0.78	1.10	<0.0010
F₄: Voltage	0.019	0.37	0.088	0.0066	−2.9	<0.0010
F₅: temperature	−0.036	0.090	0.016	0.61	−0.24	0.029
F₆: Neb. Pres.	−0.19	<0.0010	−0.20	<0.0010	−0.86	<0.0010
F₁ F₂	−0.035	0.10	0.078	0.020	−0.11	0.33
F₁ F₃	−0.083	<0.0010	−0.048	0.15	−0.074	0.51
F₁ F₄	0.075	<0.0010	0.052	0.12	0.14	0.20
F₁ F₅	0.022	0.30	0.0079	0.81	0.088	0.43
F₁ F₆	0.0061	0.78	−0.033	0.32	0.14	0.22
F₂ F₃	−0.0041	0.85	−0.021	0.51	0.10	0.37
F₂ F₄	0.012	0.57	−0.0032	0.92	−0.30	0.0098
F₂ F₅	0.027	0.22	0.013	0.69	−0.017	0.88
F₂ F₆	−0.038	0.080	0.083	0.013	−0.020	0.86
F₃ F₄	0.0094	0.66	0.017	0.60	−0.45	<0.0010
F₃ F₅	0.037	0.089	0.020	0.55	0.093	0.41
F₃ F₆	−0.047	0.032	−0.051	0.12	−0.23	0.039
F₄ F₅	−0.017	0.43	0.022	0.50	0.14	0.20
F₄ F₆	−0.0032	0.88	−0.035	0.29	0.35	0.0027
F₅ F₆	0.0055	0.80	−0.021	0.51	−0.054	0.63
F₁²	−0.11	0.020	−0.29	<0.0010
F₂²	−0.053	0.26	−0.044	0.53
F₃²	0.0085	0.85	0.047	0.51
F₄²	−0.091	0.045	−0.050	0.46
F₅²	−0.00065	0.99	−0.12	0.15
F₆²	−0.0068	0.82	0.0094	0.84
R²		0.79		0.70		0.94
Adjusted R2^e		0.69		0.56		0.92
Predicted R2^f		0.51		0.95		0.89
P-lack of fit		0.011		0.25		0.36

Migration time of the last peak.

Probability of the null hypothesis being true (the factor has no significant effect on the response) based on the F-test for comparing model variance with residual variance. Any term with P < 0.05 is considered significant, and call for rejection of null hypothesis.

Coefficient of determination adjusted for the number of terms in the model.

A measure of the amount of variation around the mean explained by the model, coefficient of determination is based on the predicted residuals from the model.