UHPLC-MS/MS Determination of Residual Tetracycline Antibiotics in Eel

Five grams of eel tissue sample were taken and its contents of residual tetracycline antibiotics (TC′s) were extracted with a solution 0.01 mol·L-1 EDTA dissolved in Mcllvaine buffer solution of pH 4.0.The aqueous extracts were defatted by extraction with n-hexane and purified by GL-Pak PLS-2 micro column,the TC′s were eluted with methanol which was evaporated to dryness by rotary evaporator at 40 ℃.The residue was dissolved with 2 mL of CH3OH+H2O (30+70) mixture,which was used for UHPLC-MS/MS analysis.Linearity ranges for determination of 4 TC′s were same in the range from 5.0-100.0 μg·L-1.Tests for recovery were made by the standard addition method at concentration levels of 5,20 and 50 μg·kg-1,and values of average recovery found were in the range of 70.6% to 93.4%,with values of RSD′s (n=6) ranged from 6.3% to 10.5%.Lower limit of determination (10S/N) of the method was found to be 5.0 μg·kg-1.