Quantitative Analysis of Carbohydrates and Artificial Sweeteners in Food Samples Using GFC- MS with APCI Interface and Post-column Reagent Addition

For the first time, a Gel Filtration Chromatography (GFC) method was established to separate eight sugars (sucrose etc), eight sugar alcohols (mannitol etc) and three sweeteners (saccharin, acesulfame K and sucralose) using pure water as mobile phase. The run time of the method was 40 minutes. It is well known that ionization of carbohydrates by atmospheric pressure ionization (API) is difficult and post-column addition of reagent such as chloroform is therefore required [1]. However, a high content of chloroform in the mobile phase (6.8%) may cause strong ion suppression and contamination to the interface and ion optics. In this study, the content of chloroform was reduced to 0.7%, which was found to be sufficient for effective ionization of the sixteen carbohydrates studied to achieve desired sensitivity. It was found that the three artificial sweeteners were ionized in negative mode too, but form [Aaccharin-H]-, [AcesulfameK-K]- and [Sucralose+Cl]- ions. The calibration curves of the sixteen carbohydrates and three sweeteners were set up using mixed standard samples with concentrations from 0.1 or 0.5 mg/L to 500mg/L. Linear calibration curves were obtained for all compounds (r2 >0.999). The limits of detection (LODs) of these compounds in neat solutions were at 0.1~1 mg/L. The repeatability of the method was evaluated and the RSD (%, n=6) of peak area obtained for 10 or 50 mg/L concentration were found below 6% except for maltitol (9.44%), lactitol (8.59%) and sorbitol (7.06%). The method was applied to a variety of liquid samples including canned soft drinks, green tea drinks, probiotic drink, Japanese "Sake", soya sauces and mouth rinse bought from supermarket and the identification results about the types of sugars and sweeteners as well as their quantification results were in accordance with the contents available on the product labels.