Effects of temperature programming and pressure on separation number and height equivalent to a theoretical plate in optimization of a serially coupled, open-tubular columns gas chromatographic system

The separation number (TZ) and the height equivalent to a theoretical plate (HETP, h) are studied in a system of two columns (GLC-GSC) coupled in series under temperature-programmed and isobaric conditions using a mixture of the first six homologous n-alkanes. The effects of four selectivity parameters (initial temperature, hold time, program rate, and midpoint pressure) on them have shown that TZ is strongly dependent on the midpoint pressure and h on the temperature. TZ and h are related inversely with a relationship that involves the overall column length (L(f) + L(b)) of the system. Examination of the basic relationship between separation number and the average carbon number showed that it is linear for this system only in the case which is linear for the back column, and this depends on the midpoint pressure.