One-step pre-column derivatization method for HPLC-UV determination of organic acids in fruit juices

Abstract

A simple and effective one-step pre-column derivatization method for reversed-phase HPLC-UV determination of the major organic acids (citric, malic, tartaric, and succinic acids) in fruit juices has been developed. The method is based on the coupling reaction of organic acids with 1-naphthylamine in the presence of N,N′-diisopropylcarbodiimide. The resulting organic acid amide derivatives were successfully separated on an AQ-C18 column and detected by a UV detector at 222 nm. Isocratic elution was performed using an acetonitrile-methanol-tetrahydrofuran-water (37:4:1:58; v/v) mixture as a mobile phase at a flow rate of 2.0 mL/min. Validation studies showed good recoveries ranging from 88.97 to 92.52% with RSD % between 2.95 and 4.56%. The detection limits obtained were 0.18, 0.48, 0.14, and 0.69 µg/mL for tartaric acid, malic acid, succinic acid, and citric acid, respectively. The method was successfully applied to three different commercial fruit juice and nectar samples with little or no clean-up procedures.