Separation of neutral compounds by high speed capillary electrochromatography

With using short capillary column packed with porous and non-porous ODS sta tionary phases, high speed separation of 6 neutral aromatic compounds withi n 36 s by capillary electrochromatography (CEC) has been performed. Good re producibility of the migration times for those solutes in high speed CEC wa s observed with RSD less than 1%. Both the linear velocity of EOF and the c urrent linearly increases with the applied voltage, which means that the th ermal effect by Joule heating was small. However, the capacity factor of so lutes was found to decrease with the increase of the applied voltage, which was caused by the fact that about several seconds needed for the increase of voltage from 0 to applied value on a commercial CE instrument made large r contributions to the migration times of the early eluted compounds than t hose of lately eluted ones during high speed CEC, and voltage effect would increase with the higher applied voltage used. The linear relationship betw een the logarithm of capacity factor and the number of carbon for homologou s compounds was observed, and positive value of slope means that the hydrop hobicity of solutes is one of the main contribution factors to retention in high speed CEC packed with ODS stationary phases.