Tandem Cation/Anion Exchange SPE Cartridge Method for Sample Desalting for HPLC Analysis of Soluble Dietary Fiber: Development and Inter-laboratory Validation

In HPLC analyses of soluble dietary fiber, desalting processes using open, mixed-bed ion-exchange columns are timeconsuming and labor-intensive. We developed and validated a simple desalting method using tandem cation/anion exchange SPE cartridges. We found that combining Bond Elut Jr SCX (upstream) and Bond Elut PSA (downstream) cartridges provided adequate desalting of test solutions. The developed method was then validated in an inter-laboratory study. Five test samples were prepared by mixing food matrixes with purified soluble dietary fiber and treated to generate solutions to test the desalting process. These solutions were then analyzed by eight different laboratories. The results demonstrated that the developed method is simple and reliable for desalting samples containing 140 to 945 mg/100 mL of soluble dietary fiber in preparation for HPLC analysis of soluble dietary fiber.