A New Cost-Efficient Technique for Analysis of Nectar Sugars and Dihydroxyacetone in Australian Leptospermum Using Liquid Chromatography–Tandem Mass Spectrometry

The commercial value of Leptospermum honey increases relative to the nonperoxide bioactivity provided by the methylglyoxal concentration in the honey, which has been shown to correlate with dihydroxyacetone (DHA) concentration in the nectar from which the honey is derived. We detail a new, reliable method to simultaneously detect and quantify DHA, glucose, fructose, and sucrose levels in Leptospermum scoparium nectar using normal phase liquid chromatography-tandem mass spectrometry. Through use of an internal standard (ribose), and a 10-fold dilution of the nectar solution, repeatable calibration curves were achieved (R-2 > 0.99). Precision was acceptable (<6%) for all analytes of interest and limits of detection ranged from 0.02 mg.L-1 (sucrose) to 1.43 mg.L-1 (glucose). The method was also effective at a 5-fold dilution and across analyte concentration ranges found naturally in L. scoparium nectar. Minimal sample preparation is required and a short analysis time of 6 min per sample is achieved, providing the Leptospermum honey industry with cost-effective and fast sample analysis.