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 mu 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 mu g/kg. The method is sensitive, accurate and precise, and can meet the requirements for the determination of pesticide residues.