Hydrophilic interaction vs ion pair liquid chromatography for the determination of streptomycin and dihydrostreptomycin residues in milk based on mass spectrometric detection

Streptomycin (SIR) and dihydrostreptomycin (DHSTR) are two of the most common aminoglycoside antibiotics used in veterinary medicine The physicochemical properties of both substances, make their determination challenging. In the present study the development of methods based on ion-pair chromatography (IPC) and on hydrophilic interaction chromatography (HILIC), for the determination of the above mentioned aminoglycosides in the range of 100-1000 mu g L-1 is described. The two methods were validated according to EU requirements for residues in food The recoveries for the IPC method were 69 3% and 56 5% of SIR and DHSTR, respectively, and for HILIC method 85 5% and 72 3%, respectively The intra- and inter-day precision, studied at 100, 200 and 300 mu g kg(-1) levels in milk samples, gave %RSD <= 13 for both methods LOQs for the HILIC method were 14 mu g kg(-1) for both analytes and for the IPC method were 109 and 31 mu g kg(-1), for SIR and DHSTR, respectively. The sensitivity of the HILIC method is 80 and 210 times greater than that of the ICP method, for SIR and DHSTR, respectively. (C) 2010 Elsevier B V All rights reserved