Free amino acids profile of Polish and Slovak honeys based on LC-MS/MS method without the prior derivatisation

LC-MS/MS method was applied for determination of free amino acids in honey without derivatisation steps. Twenty free amino acids including aspartic acid, asparagine, glutamic acid, glutamine, alanine, arginine, glycine, leucine, histidine, hydroxyproline, isoleucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, valine and ornithine were analyzed in thirty honey samples from Poland and Slovakia. The analysis covered: acacia, lime, rape, multifloral and forest types of honey. Applied method was characterized to had good sensitivity with limit of detection ranged from 3.0 ng/cm³ for valine to 13.0 ng/cm³ for hydroxyproline. Average content of proline (main amino acid component in honey) ranged from 151.46 μg/g (rape honey from Slovakia) to 389.66 μg/g for forest honey (honeydew honey) from Poland. In analyzed honeys large quantities of glutamine, glutamic acid, lysine, phenylalanine, asparagine, alanine, and valine were also found.