A simple and sensitive ion-paring HPLC-MS/MS method with negative ion mode has been developed and validated for the quantification of SA in milk.The separation was performed on C18 column with a mobile phase consisting of 4 mmol/L tetrabutylammonium hydroxide-methanol at a flow rate of 0.2 mL/min under the gradient elution.The retention time of SA was 6.1 min.Triple-quadrupole MS/MS detection was operated in negative mode by monitoring the transition of m/z 308.1>87.1 for SA.Validation results indicated that the lower limit of quantification was 0.060 mg/L and the assay showed a linear range of 0.1-100 mg/L and gave a correlation coefficient(r) of 0.998.The relative standard deviations were less than 10% at all tested concentration levels.The method has been successfully applied to the analysis of SA in milk,milk powder and breast milk.
