Table 3. Absolute Effects of Various Factors on the Retention Time Difference between Light and d₃-Labeled DNPH Derivatives Obtained from the Plackett–Burman Design^a.

factor	MDA	ACR	HNE	ONE
temperature	0.376	0.366	0.131	0.189
gradient time	0.106	0.436	0.464b,c,d	0.655b,d,e
stationary phase	0.589	0.098	0.167b	0.153
pH	0.494	0.032	0.162b	0.224
organic solvent	0.392	0.560b	0.065	0.189
analyte concn	0.249	0.299	0.228b	0.287b
dummies
dummy 1	0.310	0.161	0.067	0.009
dummy 2	0.380	0.300	0.030	0.022
dummy 3	0.036	0.168	0.073	0.189
dummy 4	0.450	0.168	0.066	0.048
dummy 5	0.319	0.164	0.032	0.087
critical effects
Ecritical	0.849	0.513	0.146	0.247
ME	0.758	0.642	0.267	0.556
SME	1.214	1.032	0.427	0.894

^aCritical effects were estimated according to Vander Heyden et al. (ref (26)).

^bSignificant effect compared to E_critical.

^cSignificant effect compared to simultaneous margin of error (SME).

^dSignificant effects from the half-probability normal plot.

^ePossibly significant effect compared to margin of error (ME).