Determination of sugars and alditols in food samples by HPAEC with integrated pulsed amperometric detection using alkaline eluents containing barium or strontium ions

The addition, in mobile phase, of alkaline-earth divalent cations such as Sr(II) and Ba(II) is shown to be a versatile means of improving the separation of alditols and carbohydrates, which are conventionally determined by high-performance anion-exchange chromatography (HPAEC) coupled with integrated pulsed amperometry using gold working electrodes. It is believed that Ba(II) or Sr(II) ions are effective both in forming solution complexes with sugar analytes, and ensuring thoroughly carbonate-free alkaline mobile phase flowing through the column. As a result, substantial benefits can be obtained in terms of peak shape, attainable column efficiency, and detection sensitivity. This work describes determination of alditols (myo-inositol, D-sorbitol, and D-mannitol), and carbohydrates (glucose, fructose, and sucrose) in some common fruits and fruit products (apricot, plum, watermelon, lemon, mandarin, grape, and dietetic cherry jam) and vegetable foodstuffs (cauliflower, cucumber, fennel, tomato, turnip, and celery). The free sugar contents in fruit juices were determined directly, without pretreatment or derivatization, following a sample extraction. While myo-inositol was found in many fruits, fruit products and vegetables examined, no presence of xylitol was detected. (C) 1998 Elsevier Science Ltd. All rights reserved.