Rapid absolute quantification of glucose and fructose isomers in honey using a boronic acid-based reactive matrix by MALDI-TOF/TOF tandem mass spectrometry

The slight structural differences between carbohydrate isomers pose considerable difficulties for their identification and quantification. Herein, a rapid method for the absolute quantification of glucose and fructose isomers using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS/MS). A novel reagent, 4-trimethylamino-6-(4-methoxy-1-naphthyl)-1,3,5-triazine-2-(3-aminophenylboronic acid) (TMNTA), was synthesized and employed as a reactive matrix. This matrix significantly enhances the ionization efficiency of monosaccharides while avoiding matrix interferences. Glucose- 13 C 6 was utilized as an internal standard for the quantitative analysis of both monosaccharides, exhibiting a strong linear correlation (R 2  ≥ 0.990). By integrating the concentration relationships of glucose and fructose derived from two diagnostic ions produced from the TMNTA-derivatized monosaccharides, this approach facilitates the absolute quantification of glucose and fructose. The method was successfully applied to the absolute quantification of these monosaccharides in honey. The proposed approach offers a simple, rapid, and high-throughput analysis of glucose and fructose isomers in complex samples.