This application note describes the use of Agilent ZORBAX Eclipse Plus C18, Eclipse Plus Phenyl-Hexyl, Eclipse XDB-Phenyl and StableBond SB-Phenyl Rapid Resolution columns to analyze nine common food additives using an isocratic solvent system. The mobile phases used include methanol or acetonitrile with 20 mM phosphate buffer at pH 2.5 or 0.2 percent formic acid. While excellent peak shape is found on all columns examined, selectivity and resolution differences are found when comparing C18 and various phenyl columns, especially the Eclipse Plus Phenyl-Hexyl and StableBond SB-Phenyl columns. In addi- tion, selectivity differences and peak shape are preserved even when using a formic acid mobile phase modifier. The use of formic acid would allow verification of unknown materials using mass spectrometry.
This document evaluates the performance of four Agilent ZORBAX columns—Eclipse Plus C18, Eclipse Plus Phenyl-Hexyl, Eclipse XDB-Phenyl, and StableBond SB-Phenyl—for the analysis of nine common non-nutritive food additives. The study utilizes a Rapid Resolution LC system with isocratic solvent systems containing methanol or acetonitrile and phosphate buffers or formic acid.
| Column Dimensions | 4.6mm x 150 mm |
|---|---|
| Particle Size | 3.5 microns |
| Flow Rate | 1.5 mL/min |
| Column Temperature | 25 °C |
| Injection Volume | 2.0 µL |
| Detection Wavelength | 220 nm |
The Eclipse Plus Phenyl-Hexyl column provides the best separation for this application under the given conditions, with a minimum resolution of R = 2.32.
Yes, the formic acid mobile phase can act as a supplementary mobile phase and would be ideal if MS detection were required.
Using acetonitrile results in significant compression of the phenyl chromatograms and a loss of selectivity differences among the C18 and phenyl columns.