Simultaneous determination of 77 pesticide residues in eight kinds of herbal tea by liquid chromatography-tandem mass spectrometry

: An effective method was developed for the determination of 77 pesticide residues in eight kinds of herbal tea by modified QuEChERS and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The target compounds were extracted with 1% (v/v) acetic acid-acetonitrile and 1 g ammonium acetate, and purified by 4 g MgSO4, 0.05 g C18, 0.50 g primary secondary amine (PSA) sorbent and 0.05 g graphitized carbon black (GCB). The 0.1% (v/v) formic acid aqueous solution and acetonitrile were used as the mobile phases. The extracts were separated on a Venusil MP C18 chromatographic column using a positive electrospray ionization (ESI) and negative ESI source under the selected ion monitoring (SIM) mode. The analytes were quantified by the matrix match standard solutions. The good linearities were obtained in the range of 0.5-100.0 μ g/L, and the correlation coefficients were all greater than 0.995. The average recoveries of the 77 pesticide residues ranged from 70.3% to 110.0%, and RSDs were in the range of 2.6%-9.8%. The limits of detection were 1.0-10.0 μ g/kg. The method is sensitive, accurate and precise, and can meet the requirements for the determination of pesticide residues.