Sensitive Analysis of Commonly Used Artificial and Natural Sweeteners Including Stevia and Their Impurities and Degradation Products

Many of the recently commercialized sweeteners have increased potency, and therefore the amount of the active ingredient added to beverages and other food products is reduced. This results in costsavings. But, this has contributed to a need for sensitive analytical methods to quantify the active product and detect low levels of breakdown products and impurities. Such product characterization is required for quality and safety issues. Traditional HPLC-UV approaches are inappropriate as these compounds typically do not possess any chromophore. This work describes a number of HPLC-CAD methods that can be used to study common natural sugars (fructose, glucose, turanose, saccharose, trehalose, maltose, melezitose, and raffinose); artificial sweeteners (sucralose, aspartame, saccharin, and acesulfame K); and newly introduced products containing Stevia extracts (rebaudioside A and stevioside). These methods provide sensitivity at low (ng) levels with good reproducibility and accuracy, and correlation to the component concentrations. Stevia products were analyzed by Charged Aerosol Detection and UV; the CAD showed a greater than fivefold improvement in sensitivity over UV for all major components. Finally, the UHPLC methods developed showed a decreased run-time and an increased sensitivity for glucose, lactose, and sucrose. Typical limits of detection were found to be <500 pg (on column) for glucose and other mono- and disaccharides. HPLC-CAD is a very flexible approach to measuring sweeteners and overcomes many of the limitations of UV, RI, LC-MS, ELSD, and HPLC-pulsed amperometric approaches.