[Determination method of isocitric acid in food additive citric acid]

A simple and rapid method using HPLC was developed for the determination of isocitric acid in food additive citric acid. One gram of sample was dissolved in 100 mL of water. HPLC separation was performed on an Inertsil ODS-3 column (4.6 mm i.d. x 250 mm) using 0.1% phosphoric acid as the mobile phase at a flow rate of 1 mL/min. Isocitric acid was detected at 210 nm. The calibration graph was rectilinear from 5 to 100 micrograms/mL. The recoveries of isocitric acid from sample at the levels of 0.1% and 0.4% were 98% and 99%, respectively, and the determination limit was 0.05%.