Analysis of sugars in bee pollen and propolis by ligand exchange chromatography in combination with pulsed amperometric detection and mass spectrometry
The analysis of sugars in the natural products propolis and bee pollen was carried by high-performance thin layer chromatography (HPTLC), high-performance ligand exchange chromatography with pulsed amperometric detection (HPLEC-PAD) and HPLEC coupled to liquid chromatography–electrospray ionisation mass spectrometry (LC–ESI-MS) in the positive ion mode. Eleven samples of propolis were analysed, most of which contained no sugars or only traces of sugars. Similar analysis was performed on five samples of bee pollen which were found to contain glucose, fructose and sucrose. These sugars were quantified by HPLEC-PAD. LC–ESI-MS analysis also indicated small amounts of a trisaccharide in the samples. Calibration curves were linear in the range 0.005–0.5 mg/ml and the LOD for all the sugars was <0.005 mg/ml. The positive ESI-MS of the sugars extracted from bee pollen yielded mainly Ca2+ adducts of sugars, which afforded good sensitivity for their detection.