Effect of Organic Solvent Concentration (1)

Nnonylphenol ethoxylate, a nonionic surfactant was analyzed using Asahipak GF-310 HQ (a multisolvent GPC column).
The figure shows the effect of organic solvent concentartion on elution time for Nnonylphenol ethoxylate of different degree of POE polymerization.
The elution characterstics of Nnonylphenol ethoxylate are different in the following three areas:
Area 1
The organic solvent concentration is lower than 20%. In this area, surfactants are adsorbed on the packing material and no peak appears in the chromatogram.
Area 2
The organic solvent concentration is medium, 20 to 60%. Surfactants are reteined by mainly hydrophobic interaction with packing maetrials and can be separated each other.
Area 3
The organic solvent concentration is higher than 60%. Surfactants cannot be retained by hydrophobic interaction with packing materials and elute as the single peak. This condition is good for microchemical analysis of trace of components.
Moreover, the elution characterstics of surfactants using GF-310 HQ has important features as follows:
1) The recoveries of surfactants are very high unless they are adsorbed. Refer to the table.
2) The surfactant of which molecular weight is larger elutes faster.

Degree of POE Polymerization(n)	Acetonitrile Concentration (%)
	0	25	50	75	100
100	Adsorption	100	100	100	100
60	Adsorption	80	100	100	100
45	Adsorption	Adsorption	100	100	100
20	Adsorption	Adsorption	100	100	100
10	Adsorption	Adsorption	100	100	100

Sample : Nnonylphenol ethoxylate

Column       : Shodex Asahipak GF-310 HQ (7.5mmID*300mm)
Flow rate    : 0.6mL/min
Detector     : UV(280nm)
Column temp. : 30deg-C