HPLC-fluorimetric method for analysis of amino acids in products of the hive (honey and bee-pollen)

Abstract

An optimization of the OPA method has made feasible separation and quantification of 23 amino acids, which include 5 infrequently searched for. Detection limits ranged from 0.24 to 10.1 pmol in honey and from 29.1 to 0.42 pmol in bee-pollen; reproducibility (C.V.) ranged from 5.3% to 20.4%; recoveries were above 78.8%. Forty monovarietal honey samples from ilex, oak, heather and chestnut-tree were analyzed for their free amino acid profiles. α-Aminoadipic acid and homoserine are reported for the first time in honeys. Thirty-two samples of Spanish bee-pollen, made of a majority of pellets from Cistus Ladanifer (67.1%) and Echium plantagineum (8.9%), were analyzed for their free and total amino acid profiles. Free γ-aminobutyric acid was extensively found with an average of 0.53 mg/g, while Hser and Orn were infrequent. Manually separated monofloral pellets from Cistus ladanifer and Echium plantagineum were analyzed for their free amino acid contents (including proline): 32.46 and 21.87 mg/g for the former and 22.18 and 12.23 mg/g for the latter. In contrast, the total amino acid percentage (on a dry weight basis) was 13.95% for Cistus ladanifer and 32.22% for Echium plantagineum.