Experimental achievement of one million theoretical plates with microbore liquid chromatographic columns

Following the theoretical predictions, the experimental achievement of 1 X 10/sup 6/ theoretical plates with concatenated packed microbore columns has been demonstrated. Stainless steel columns (1 m X 1 mm i.d.) were packed with Zorbax silica gel, nominal diameter 7-8 ..mu..m, by a method described elsewhere. The columns selected for subsequent coupling in series at least afforded 40,000 theoretical plates and a flow resistance parameter around 600. A 22 m long column was obtained which produced 10/sup 6/ plates at flow rates of 13-15 ..mu..L.min/sup -1/ under an inlet pressure of 600-700 bar. The reduced plate height was 3.3, the flow resistance parameter was 820, and the separation impedance was about 9700. To illustrate the enormous separation power of this column, the chromatogram of a light gasoline sample is given, which affords resolution larger than unity for compounds having a selectivity coefficient of 1.01-1.02. This column now has been working for more than 2 months without performance alteration.