Effect of Flow-Rate and Sample-Size on Column Efficiency in Gas-Liquid Chromatography

Abstract

THERE have been a number of investigations as to the effect of carrier gas flow-rate on separation and column efficiency in gas-liquid chromatographic systems^1–4. Many of the results present contradictory pictures of the effect exerted by this parameter. Keulemans¹ states, “for a certain set of operational conditions there is an optimum linear gas velocity, but the optimum is very flat and the gas rate is consequently not a highly critical parameter”. James and Martin² have shown that column efficiency is sensitive to flow-rate and that a decrease in flow-rate increases column efficiency. Their results show a 27 per cent increase in column efficiency when the flow-rate was decreased from 24 to 10 ml./min. Bethea and Wheelock³ reported that column efficiency, as measured by the H.E.T.P., is approximately tripled by raising the flow-rate from 5 to 27.5 ml./min. They found that increasing the flow-rate beyond the latter point gave only meagre increases in efficiency.