Determination of multi-pesticides in black tea by subcritical water extraction and gas chromatography-tandem mass spectrometry

Abstract

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method with subcritical water extraction was developed for the determination of 21 organochlorine and pyrethroid pesticides in black tea. Under the extraction pressure of 5 MPa, the target compounds were extracted with subcritical water at the temperature of 150 degrees C for 15 min, transferred into acetone-n-hexane (1:1, v/v), and cleaned-up by an ENVI-Carb solid phase extraction (SPE) column. The GC separation was performed on a DB-5 capillary column. The pesticides were determined by MS/MS in multiple reaction monitoring (MRM) mode and quantified by matrix-matched internal standard method. The calibration curves showed good linearities in the range of 5.0-320.0 microg/L with the correlation coefficients greater than 0.99. The limit of quantification (S/N > 10) was 50 ng/g, and the limit of detection (S/N > 3) was 10 ng/g. The recoveries of pesticides spiked in the tea at three levels of 50, 100 and 200 ng/g were ranged from 70. 18% to 119.98% with the relative standard deviations (RSDs) of 5.01%-11.76%. The sensitivity, accuracy and precision of the method meet the technical standard of the pesticide determination. The method can be applied to the determination of organochlorine and pyrethroid pesticides in black tea.

Determinations for Pesticides on Black, Green, Oolong, and White Teas by Gas Chromatography Triple-Quadrupole Mass Spectrometry

“…The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction procedure has also been adapted for use on tea leaves after adding water to the dry tea, ,,, then using GC-MS/MS ,, and LC-MS/MS , and/or LC-QTOF for measurement. Other methods for extraction have also been employed, for example, pressurized solvent extraction with ethyl acetate/hexane or subcritical water …”

“…Other methods for extraction have also been employed, for example, pressurized solvent extraction with ethyl acetate/ hexane 13 or subcritical water. 14 Acetonitrile extracts using QuEChERS from botanicals like tea have too much co-extracted matrix to be injected directly into GC-MS. 3,6,12 Cleanup methods have included using dispersive SPE (as used in QuEChERS with the addition of GCB 4 or with CaCl 2 instead of MgSO 4 6,12 ), using dispersive multiwalled carbon nanotubes, 15 using liquid:liquid extraction (LLE), 5 or using an SPE column containing PSA and GCB. 3,10 Recently, comparisons of three 9,16 or four 6 different extraction and cleanup procedures have been published, although some with mixed conclusions.…”

Synthesis and characterization of ZnO-nanorods loaded onto activated carbon and its application for efficient solid phase extraction and determination of BG from water samples by micro-volume spectrophotometry

“…Efforts devoted to simplifying the extraction procedure and greatly decrease in the consumption of organic solvents lead to the generation of suspended droplet microextraction (SDME), 15 cloud point extraction (CPE) 16 and subcritical water extraction (SCWE). 17 On the other hand, the distinguish superiority of dispersive solid-phase microextraction (DSPME) 18 to LLE are lower consumption of organic solvents and higher enrichment factor, while routine DSPME still is a time-consuming approach. Nano-particles as novel sorbents attain great interest for preconcentration of trace elements and toxic dyes owing to their effectiveness and high number of reactive atoms.…”