title: Ion-Exclusion High-Performance Liquid Chromatography of Aliphatic Organic Acids Using a Surfactant-Modified C18 Column.
abstract: Ion exclusion chromatography (IELC) of short chain aliphatic carboxylic acids is normally done using a cation exchange column under standard HPLC conditions but not in the ultra-HPLC (UHPLC) mode. A novel IELC method for the separation of this class of carboxylic acids by either HPLC or UHPLC utilizing a C18 column dynamically modified with sodium dodecyl sulfate has been developed. The sample capacity is estimated to be near 10 mM for a 20 µL injection or 0.2 µmol using a 150 × 4.6 mm column. The optimum mobile phase determined for three standard mixtures of organic acids is 1.84 mM sulfuric acid at pH 2.43 and a flow rate of 0.6 mL/min. Under optimized conditions, a HPLC separation of four aliphatic carboxylic acids such as tartaric, malonic, lactic and acetic can be achieved in under 4 min and in <2 min in the UHPLC mode at 2.1 mL/min. A variety of fruit juice and soft drink samples are analyzed. Stability of the column as measured by the retention order of maleic and fumaric acid is estimated to be ∼4,000 column volumes using HPLC and 600 by UHPLC. Reproducible chromatograms are achieved over at least a 2-month period. This study shows that the utility of a C18 column can be easily extended when needed to IELC under either standard or UHPLC conditions.
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Fasciano
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA.
authors.forename: Fotouh R
authors.initials: FR
authors.lastname: Mansour
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA danielnd@miamioh.edu.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Danielson