Development of identification method for isopropyl citrate

In Japan's Specification and Standards for Food Additive, 8th edition, two identification tests involving isopropyl citrate for detecting isopropyl alcohol and citrate are stipulated. However, these identification tests use mercury compound, which is toxic, or require a time-consuming pretreatment process. To solve these problems, an identification test method using GC-FID for detecting isopropyl alcohol was developed. In this test, a good linearity was observed in the range of 0.1-40 mg/mL of isopropyl alcohol. While investigating the pretreatment process, we found that isopropyl alcohol could be detected using GC-FID in the distillation step only, without involving any reflux step. The study also showed that the citrate moiety of isopropyl citrate was identified using the solution remaining after conducting the distillation of isopropyl alcohol. The developed identification tests for isopropyl citrate are simple and use no toxic materials.