Improved Efficiency in Gas Chromatography by Molecular Sieve Flour

Abstract

IT has been demonstrated that columns packed with 5A molecular sieve flour dispersed on conventional ‘Chromosorb’ support perform better than columns packed with crushed molecular sieve pellets1. This is illustrated in Fig. 1 by the chromatograms showing tho separation of air. Curve A was produced with a 2 m × ¼ in. column packed with 60/80 mesh 5A molecular sieve. Curve B was produced with an equal-dimension column packed with 28 per cent molecular sieve flour coated on 60/80 mesh red ‘Chromosorb’. The molecular sieve column provides only 97 plates compared with 562 plates for the mixed column. Expressed as height equivalent to a theoretical plate, this represents a decrease from 20.6 mm to 3.5 mm and a six-fold increase in efficiency. Separations were at room temperature with flow-rates near 50 ml./min. of helium. The sample was 2 ml. of air.