LC-MS/MS Determination of Residual Amounts of Sulfonamides and Quinolones in Aquatic Products

The sample of aquatic products (5.00 g) was extracted with 20 mL of a mixture of acetonitrile and formic acid (99+1). The extract was dehydrated with absolute ethanol. The extract was then concentrated and 2 mL of n-hexane was added to remove fat. LC separation was performed by using ACQUITY UPLC BEH HILIC chromatographic column as stationary phase, and mixtures of methanol and 0.1% (φ) formic acid solution with various ratios as mobile phase in gradient elution. ESI⁺ and multi-reaction-monitoring were adopted in MS/MS. Internal standard method was used for quantification. Linearity ranges of the 11 drugs were found in the same range of 5-200 μg·L^-1, with lower limits of determination (10S/N) in the range of 0.07-0.20 μg·kg^-1. Tests for recovery were made by standard addition method at 3 concentration levels of 1.0, 4.0, 20.0 μg·kg^-1, giving values of recovery and RSD's (n=6) in the ranges of 80.3%-119% and 1.3%-12% respectively.