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Citation
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HERO ID
3350323
Reference Type
Journal Article
Title
Micellar and sub-micellar ultra-high performance liquid chromatography of hydroxybenzoic acid and phthalic acid positional isomers
Author(s)
Fasciano, JM; Danielson, ND
Year
2016
Is Peer Reviewed?
Yes
Journal
Journal of Chromatography A
ISSN:
0021-9673
EISSN:
1873-3778
Publisher
ELSEVIER
Location
AMSTERDAM
Volume
1438
Page Numbers
150-159
Language
English
PMID
26896919
DOI
10.1016/j.chroma.2016.02.024
Web of Science Id
WOS:000371941500016
URL
https://linkinghub.elsevier.com/retrieve/pii/S0021967316301108
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Abstract
Micellar liquid chromatography (MLC) has been used primarily for the separation of neutral analytes of varying polarities, most commonly phenols and polyaromatic hydrocarbons, but does not seem to have been used to study aromatic hydroxy acids in detail. We have studied the separation of hydroxybenzoic acid mixtures, including monohydroxybenzoic and dihydroxybenzoic acid positional isomers by MLC. Sodium dodecylsulfate (SDS) is investigated as the modifying surfactant on a C18 ultra-high performance liquid chromatography (UHPLC) column (100 × 2.1mm, 1.8 μm). The addition of only SDS (no organic solvent) to the mobile phase reduced the influence of hydrophobic interactions while improving the retention times, resolution, and peak shapes, even at concentrations below the critical micellization concentration (CMC). The UHPLC separation of 7 hydroxybenzoic acids, including 6 dihydroxybenzoic acid positional isomers and one trihydroxybenzoic acid, is achieved with high efficiency using 0.1% SDS in 1.84 mM sulfuric acid (pH 2.43) mobile phase, in less than 6 min with a flow rate of 0.3 mL min(-1), and in less than four min with a flow rate of 0.7 mL min(-1). Six monohydroxybenzoic acid isomers are also effectively separated by MLC, using a 0.5% SDS mobile phase modifier, in less than 20 min with a flow rate of 0.3 mL min(-1), and in less than 14 min with a flow rate of 0.7 mL min(-1). The 3 phthalic acid isomers could be separated using a similar mobile phase and flow rates in less than 6 and 4 min. Solute-micelle equilibrium constants and partition coefficients are calculated for 6 monohydroxybenzoic acids based on a plot of MLC retention factor vs. mobile phase micelle concentration. All aromatic acid isomers studied can be classified as binding solutes in the MLC retention mechanism. Less effective separations are observed with shorter chain surfactants, leading to higher retention times and poor peak shapes. It is concluded that increasing chain length led to more efficient MLC separations, and SDS is the preferred modifying surfactant for the examined separation.
Tags
IRIS
•
Dibutyl Phthalate (DBP)
Database Searches
Litsearch Jan 2016 - July 2016
Pubmed
Excluded: No Primary Data on Health Effects
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