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

• Published in: Rapid communications in mass spectrometry 2003-01, Vol.17 (15), p.1735-1742
• Main Authors: Ayorinde, Folahan O., Bezabeh, Dawit Z., Delves, I. G.
• Format: Article
• Language: English
• Subjects: Ascorbic Acid - analysis; Beverages - analysis; Carbohydrates - analysis; Citric Acid - analysis; Sodium Benzoate - analysis; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.1113

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 [CitricH+2K]+, [Citric2H+3K]+, and [Citric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 [Citric2H+CH3+2K]+, [Citric3H+2CH3+2K]+, and [Citric3H+CH3+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. Copyright © 2003 John Wiley & Sons, Ltd.