Use of a Headspace Solid-Phase Microextraction-Based Methodology Followed by Gas Chromatography-Tandem Mass Spectrometry for Pesticide Multiresidue Determination in Teas

This study reports on the development of a fast and efficient method based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-tandem mass spectrometry (GC-MS/MS) for simultaneous analysis of 128 volatile or semi-volatile pesticide residues belonging to nine classes of pesticides. The important factors related to HS-SPME performance were optimized; these factors include fiber types, water volume, ion strength, extraction temperature, and extraction time. The best extraction conditions include a PDMS/DVB fiber, and analytes were extracted at 90 A degrees C for 60 min from 1 g of tea added to 5 mL of 0.2 g mL(-1) NaCl solution. The methodology was validated using tea samples spiked with pesticides at three concentration levels (10, 50, and 100 mu g kg(-1)). In green tea, oolong tea, black tea, and puer tea, 82.8, 88.3, 79.7, and 84.3% of the targeted pesticides meet recoveries ranging from 70 to 120% with a relative standard deviation of 20%, respectively, when spiked at a level of 10 mu g kg(-1). Limits of quantification in this method for most of the pesticides were 1 or 5 mu g kg(-1), which are far below their maximum residue limits prescribed by EU. The optimized method was employed to analyze 30 commercial samples obtained from local markets; 17 pesticide residues were detected at concentrations of 2-452 mu g kg(-1). Chlorpyrifos was the most detected pesticide in 80% of the samples, and the highest concentration of dicofol (452 mu g kg(-1)) was found in a puer tea. This is the first time to find that the optimized extraction temperature for pesticide residues is 90 A degrees C, which is much higher than other reported HS-SPME extraction conditions in tea samples. This developed method could be used to screen over one hundred volatile or semi-volatile pesticide residues which belong to multiple classes in tea samples, and it is an accurate and reliable technique.