HPLC-MS/MS Determination of Residual Amounts of 8 Antibiotics in Waters of Drinking Water Source with Enrichment by Solid Phase Extraction

A method of HPLC-MS/MS for the simultaneous determination of residual amounts of 8 antibiotics in water sample from drinking water source with enrichment by solid phase extraction was proposed. The pretreated water sample was adjusted to pH 2.5 or pH 3.2, and was passed through the Oasis HLB SPE microcolumn for enrichment and purification of the analytes. XBridge C18 chromatographic column was used as stationary phase, and the mixture of (A) 10 mmol·L-1 formic acid solution and (B) 10 mmol·L-1 formic acid-methanol solution in different ratios was used as mobile phase in gradient elution. In MS/MS analysis, ESI+, ESI-and mode of multi-reaction monitoring were adopted. Linear relationship between values of peak area and mass concentration of the 8 antibiotics was kept in the same range of 1.00-400 μg·L-1, with detection limits (3S/N) in the range of 0.4-0.7 ng·L-1. Values of recovery measured by standard addition method were in the range of 81.9%-110%, with RSD′s (n=7) in the range of 0.7%-4.5%.