Bee pollen is one of the hive products that is of most interest today due to its multiple beneficial health properties, making it an increasingly popular food supplement. Bee pollen contains many bioactive compounds, such as fatty acids, vitamins, minerals, proteins, and amino acids, among others. In the present study, the free amino acid content was determined in bee pollen by using liquid chromatography coupled to a fluorescence detector. Sample treatment consisted of a solvent extraction of the free amino acids with ultrapure water and a further centrifugation of the extract, which was repeated twice. After that, it was necessary to perform a pre-column derivatization of the amino acids using a combination of two reagents (o-phthalaldehyde and 9-fluorenylmethyl chloroformate) prior to their separation in a Gemini® C18 reverse phase column in gradient elution mode. The analytical performance was evaluated, and several commercial bee pollen samples were analyzed. Significant differences in the free amino acid profile and concentration, which ranged between 19 and 192 mg/g, were observed depending on the botanical origin of the samples.
A new LC-ESI-MS method was developed for the determination of residues of the antibacterial tylosins A, B, C and D in honey. The procedure employed an SPE on polymeric cartridges for the isolation of tylosins from diluted honey. Chromatographic separation of the tylosins was performed on a C18 column (150 x 4.60 mm2 ID, 5 microm) using a ternary gradient made of formic acid 1% in water (solvent A), methanol (solvent B) and ACN (solvent C) as mobile phase, at 30 degrees C and at a flow rate of 0.8 mL/min. Average analyte recoveries for the studied compounds ranged from 89 to 106% in replica sets of fortified honey samples. The detection limits for the four drugs studied were between 2 and 3 microg/kg. The developed method has been applied to the analysis of tylosin residues in honey from veterinarian treated beehives fed with the technical product, which contains the four compounds and is a new candidate antibiotic to treat American foulbrood disease of honey bee colonies.
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