Quantitative analysis of acid-catalyzed levulinic acid product mixture from cellulose by mixed-mode liquid chromatography

Abstract

A mixed-mode weak anion-exchange/reversed-phase liquid chromatography (LC) column was successfully applied for the analysis of levulinic acid (4-oxopentanoic acid, LA) product mixture derived from cellulose. Due to the existence of ionic and neutral byproducts, the analysis of the product mixture usually requires ion chromatography, LC and gas chromatography simultaneously. The new method enables accomplishment of the analysis in one LC run within 6min. LC mobile phase of 10mM phosphate buffer containing 5% acetonitrile with pH=5.5 was used. The linear regression coefficients for the UV signal of standard compounds with the corresponding mass concentrations were greater than 0.999. The method recoveries were between 98.57–103.48%. The limits of quantification were 5, 10,1000, 1500 and 3000ng/mL for 5-hydroxymethylfurfural, furfural, acetic acid, formic acid and LA respectively. The mixed-mode column exhibits comprehensive separation mechanism of both reversed-phase and ion-exchange interactions. The mobile phase with different pH, organic modifier solvent and buffer concentration provided flexible LC method for the sample with different complexity.