title: Preliminary investigation of the simultaneous detection of sugars, ascorbic acid, citric acid, and sodium benzoate in non-alcoholic beverages by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used for the simultaneous detection of sugars, ascorbic acid, citric acid, sodium and/or potassium benzoate in non-alcoholic beverages, with meso-tetrakis(pentafluorophenyl)porphyrin (MW 974) as a matrix. Using potassium hydroxide as dopant, fructose/glucose was detected as the potassiated molecule at m/z 219, whereas potassiated sucrose, [Sucrose. K](+), was detected at m/z 381. Using sodium hydroxide as dopant, the fructose and sucrose ions were detected at m/z 203 and 365, respectively. Citric acid generated multiple ions at m/z 269, 307, and 345, which were assigned to [Citricbond;H+2K](+), [Citricbond;2H+3K](+), and [Citricbond;3H+4K](+), respectively. However, a stored methanolic solution of citric acid produced additional ions at m/z 283, 297, and 321, which were attributed to [Citricbond;2H+CH(3)+2K](+), [Citricbond;3H+2CH(3)+2K](+), and [Citricbond;3H+CH(3)+3K](+), respectively, due to esterification that took place during storage. The limits of detection in water were: ascorbic acid, 0.30 wt%; citric acid, 0.5 wt%; and sodium benzoate, 0.001 wt%. In the beverage formulations, the limits of detection were: ascorbic acid 0.3 wt%, citric acid 0.3 wt%, and sodium benzoate 0.02 wt%. Spiking a water or beverage solution that contained ascorbic and/or citric acid with less than 0.6 wt% of tartaric acid lowered the detection limits of ascorbic and citric acids to 0.2 wt%. This study demonstrates the potential for using MALDI-TOFMS in the quality control analyses of non-alcoholic beverages, particularly with regard to the detection of low molecular weight organic acids in commercial beverage formulations.
authors.affiliation: Department of Chemistry, Howard University, Washington, DC 20059, USA. fayorinde@howard.edu
authors.forename: Folahan O
authors.initials: FO
authors.lastname: Ayorinde
authors.forename: Dawit Z
authors.initials: DZ
authors.lastname: Bezabeh
authors.forename: I G
authors.initials: IG
authors.lastname: Delves
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D002241:Carbohydrates / Q000032:analysis*; D019343:Citric Acid / Q000032:analysis*; D020160:Sodium Benzoate / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D002241:Carbohydrates; D019343:Citric Acid; D020160:Sodium Benzoate; D001205:Ascorbic Acid