In order to develop this method, the results of which have been published recently in the Journal of Agricultural and Food Chemistry, the researchers employed ultra performance liquid chromatography, a technique that makes it possible to separate the components of a sample, together with mass spectrometry, which permits the simultaneous identification of up to 17 antibiotics.
"The development of these multi-residue methods is very useful, since it makes it possible to detect the various groups of antibiotics within a sample, and with just one analysis", stresses Garrido. In addition, the chromatography analysis takes less than 10 minutes, "which means it could be routinely used in laboratories".
The researcher points out that European legislation today establishes a "zero tolerance" policy when it comes to the presence of antibiotic residues in honey, and the analytical methods devised by the study help to identify these compounds at the lowest levels possible. The technique developed by the chemists at the UAL means they can be identified at concentrations of between 0.1 and 1 microgram per kilo of honey, depending upon the type of antibiotic.
Antibiotic residues in honey
The researchers have applied their analytical method to 16 honey samples, 11 of which were taken from supermarkets while five were collected from various private beekeepers throughout Granada and Almería. The results of the study show that three of the samples contained traces of the antibiotics used to treat diseases among bees.
One of the commercial samples contained 8.6 micrograms of erythromycin per kilo of honey, while traces of sarafloxacin were found in another. This antibiotic, along with residues of tylosin, sulfadimidine and sulfachlorpyridazine, were also found in the honey from one bee farm, which was informed about the results.
Garrido stresses that the low concentrations of antibiotics detected "do not represent a direct risk to the consumer", but warns that excessive or undue use of these veterinary products could have an affect on food security.