On-line concentration of neomycin and screening aminoglycosides in milk by short capillary column and tandem mass spectrometry.

An MS-MS method was established for the trace analysis of neomycin and screening aminoglycoside antibiotics (such as amikacin, gentamicin, kanamycin, and tobramycin) in a milk sample. The extraction and purification are based on ion-pair SPE technology on a short fused-silica capillary RP C18 column. The capillary SPE column provided the stationary phase to retain aminoglycoside antibiotics and MS-MS compatible organic acid heptafluorobutyric acid (HFBA) was used as protein precipitation and ion-pair reagent. Aminoglycosides were extracted in this short column and directly eluted to MS-MS without evaporating to dryness and reconstituted with MS-MS compatible solvent after SPE. The LOQ was 0.1 microg/mL and the calibration curve was linear up to 6.4 microg/mL. A small amount of milk product, 10 microL, is sufficient for the analysis and application of this method as the trace analysis of neomycin in the biological matrix proved simple and workable.