Separation of Isomer Peaks

Nonylphenol is a very hydrophobic compound and is suitable for analysis by Normal Phase. It is produced commercially by Acid-catalyzed Alkylation of Phenol with a mixture of nonenes. Therefore a variety of product isomers are possible, with different branching of the C9 group and position of the chain on the ring.

Normal Phase HPLC is well-suited to isomer separations and in this method, separation was observed between the main peak and two smaller peaks. Three runs are shown to illustrate the repeatability, which is often a concern with Normal Phase Methods that use ordinary Silica Columns.

Main Peak:

Method Conditions
Column: Cogent Silica-C™, 4µm, 100Å
Catalog No.: 40000-10P
Dimensions: 4.6 x 100mm
Mobile Phase:
A: Ethyl Acetate
B: Hexane

Time (minutes) %B
0 100
4 100
19 90
20 100

Post Time: 3 minutes
Injection vol.: 1µL
Flow rate: 1.0mL / minute
Detection: UV @ 277nm
Sample Preparation: Nonylphenol reference standard dissolved in a Hexane diluent.
t0: 1.3 minutes

Note: Nonylphenols are used in synthesis as a starting material for various surfactants. They are subjected to Ethoxylation to produce Alkyl-Phenol Ethoxylates.


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