This article describes the comparison of different versions of an easy, rapid and low-cost sample preparation
approach for the determination of pesticide residues in fruits and vegetables by concurrent use
of gas and liquid chromatography (GC and LC) coupled to mass spectrometry (MS) for detection. The
sample preparation approach is known as QuEChERS, which stands for “quick, easy, cheap, effective,
rugged and safe”. The three compared versions were based on the original unbuffered method, which
was first published in 2003, and two interlaboratory validated versions: AOAC Official Method 2007.01,
which uses acetate buffering, and European Committee for Standardization (CEN) Standard Method EN
15662, which calls for citrate buffering. LC–MS/MS and GC-MS analyses using each method were tested
from 50 to 1000 ng/g in apple-blueberry sauce, peas and limes spiked with 32 representative pesticides.
As expected, the results were excellent (overall average of 98% recoveries with 10% RSD) using all 3
versions, except the unbuffered method gave somewhat lower recoveries for the few pH-dependent pesticides.
The different methods worked equally well for all matrices tested with equivalent amounts of
matrix co-extractives measured, matrix effects on quantification and chemical noise from matrix in the
chromatographic backgrounds. The acetate-buffered version gave higher and more consistent recoveries
for pymetrozine than the other versions in all 3 matrices and for thiabendazole in limes. None of
the versions consistently worked well for chlorothalonil, folpet or tolylfluanid in peas, but the acetatebuffered
method gave better results for screening of those pesticides. Also, due to the recent shortage in
acetonitrile (MeCN), ethyl acetate (EtOAc) was evaluated as a substitute solvent in the acetate-buffered
QuEChERS version, but it generally led to less clean extracts and lower recoveries of pymetrozine, thiabendazole,
acephate, methamidophos, omethoate and dimethoate. In summary, the acetate-buffered
version of QuEChERS using MeCN exhibited advantages compared to the other tested methods in the
Posted: July 12, 2012, 10:49 am
ATAS GL International B.V. has changed her name into GL Sciences B.V.. We are based in Eindhoven, The Netherlands. Founded in 1990, GL Sciences B.V specializes in development and manufacturing of...