Alkali Metal Modification of Silica Gel-Based Stationary Phase in Gas Chromatography

Table 3

Thermodynamic parameters of parent and modified silica stationary phases.

Columns	Solutes	−Δ𝐺 KJmol^−1	−Δ𝐻 KJmol^−1	−Δ𝑆 Jmol^−1 degree^−1
Si	n-Heptane	12.38	37.66	67.79
	Methylcyclohexane	12.19	35.12	61.47
	Toluene	18.35	45.79	73.54
SiNa	n-Heptane	8.89	36.58	74.25
	Methylcyclohexane	9.45	32.76	62.49
	Toluene	12.77	41.19	76.22
SiNa10%	n-Heptane	12.2	24.84	33.9
	Methylcyclohexane	12.07	23.86	31.62
	Toluene	15.30	28.27	34.78
SiC500	n-Heptane	9.38	34.89	68.38
	Methylcyclohexane	9.10	31.27	59.44
	Toluene	14.01	40.84	71.93
SiC	n-Heptane	4.55	26.68	59.33
	Methylcyclohexane	4.37	25.21	55.88
	Toluene	9.39	29.81	54.73
SiCNa	n-Heptane	8.48	21.37	34.56
	Methylcyclohexane	8.64	19.86	30.10
	Toluene	10.75	23.63	34.53