Syringe cleanup with UHPLC-MS/MS for nitroimidazoles and steroids detection in manure-based fertilizers

A syringe-dispersive solid-phase extraction method was developed for the determination of seven nitroimidazoles and nine steroids in manure-based fertilizers by ultra-high performance liquid chromatography with tandem mass spectrometry. Methanol and acetonitrile were used to extract the sample, and mixed dispersive sorbents dispersed in the syringe were used for purification. The extract was separated with an HSS-T3 column and detected in positive or negative multiple reaction monitoring mode. Under the optimal conditions, the recoveries of the 16 compounds ranged from 70.3 to 112.3% at the four spiked levels (3, 10, 20, and 50 μg/kg) and the relative standard deviations ranged from 1.0 to 12.4%. The limits of detection and quantification were 0.22-0.86 and 0.73-2.87 μg/kg, respectively. This method is simple, fast, and reliable, and can be used to simultaneously screen and determine nitroimidazoles and steroids in manure-based fertilizers.