Optimization of Separation and Detection Conditions for the Multi Residue Analysis of Organochlorine and Organophosphorus Pesticides by GC-MS/MS”
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ABSTRACT: A multi-residue method has been developed and validated for the simultaneous quantification and confirmation of around 130 multiclass pesticides in orange, nectarine and spinach samples by GC-MS/MS with a triple quadrupole analyzer. Compounds have been selected from different chemical families including insecticides, herbicides, fungicides and acaricides. Three isotopically labeled standards have been used as surrogates in order to improve accurate quantitation. Samples were extracted by using accelerated solvent extraction (ASE) with ethyl acetate. In the case of spinach, an additional clean-up step by gel permeation chromatography was applied. Determination was performed by GC-MS/MS in electron ionization mode acquiring two MS/MS transitions for each analyte. The intensity ratio between quantitation transition (Q) and identification transition (q) was used as confirmatory parameter (Q/q ratio). Accuracy and precision were evaluated by means of recovery experiments in orange, nectarine, and spinach samples spiked at two concentration levels (0.01 and 0.05 mg/kg). Recoveries were, in most cases, between 70% and 120% and RSD were below 20%. The limits of quantification objective for which the method was satisfactorily validated in the three samples matrices were for most pesticides 0.01 mg/kg. Matrix effects over the GC-MS/MS determination were tested by comparison of reference standards in pure solvent with matrix-matched standards of each matrix. Data obtained showed enhancement of signal for the majority of analytes in the three matrices investigated. Consequently, in order to reduce the systematic error due to this effect, quantification was performed using matrix-matched standard calibration curves. The matrix effect study was extended to other food matrices such as raisin, paprika, cabbage, pear, rice, legume, and gherkin, showing in all cases a similar signal enhancement effect.Analytical and Bioanalytical Chemistry 03/2010; 397(7):2873-91. · 3.66 Impact Factor
- Determination of Pesticide Residues in Fruits and Vegetables. 301-331..
M.C.Khetagoudar, Mahadev B. Chetti.,* Deepa G.T., P.T.Goroji, Dinesh B.K.
Pesticide Residue Testing Laboratory, UAS, Dharwad 580 005, Karnataka, India,
*(Corresponding author's E-mail : email@example.com)
Introduction Validation study
Sl. Window tRName of Precursor Product CollisionConc.
No.(min) (min) Compounds ion (m/z) ion (m/z) energy(ppb)
Results and Discussion
M Pesticides are widely used to protect the crops from a variety of
pests. The use of pesticides benefits in increasing agricultural
production but the repeated and indiscriminated uses of
pesticides have led to their accumulation in plants, animals and
thus effecting widespread contamination of the environment.
2 10.03 Phorate260
M Application of excess pesticides leads to accumulation of residues
3 10.75 Lindane181145 1010
which remains on fruits and vegetables, constituting a potential risk
10.75111 7510 10
to consumers. Fruits and vegetables are the foods that receive the
4 11.03 Chlorothalonil266 1332650
highest doses of pesticides.
512-13 12.42 Fenitrothion 277260550
12.42 20616211 50
6 12.59 Malathion 1731275 50
12.58173 9910 50
712.73 Chorpyriphos 314258 1250
12.73 197 16916 50
8 12.81 Fenthion278109 1250
12.81278 245 12 50
9 12.84 Aldrin26319322 100
12.84293186 30 100
10 12.87 Parathion291109 1050
1113-1413.66 Phenthoate274 1218 50
1213.68 Dimethoate12547 20500
1313.70 Quinalphos146118 710
13.70 157102 20 10
1414-1514.28 A- endosulphan240.9 205.91050
15 14.66 4,4-DDE246176 2610
16 14.57 Profenfos33926910100
1714.80 2,4-DDD235 1651610
1815-1815.18 Endrin263193 30 100
19 15.38 B- endosulphan195 1604 50
15.38 195159 6 50
20 15.43 Ethion 231129 1850
21 15.70 Triazophos257 16210 100
2217.33 Anilophos22615712 100
Table1: Experimental conditions of the optimized GC MS/MS
Linearity - Assumed when regression coefficient was >0.99 with
residuals lower than 30%.
Selectivity - Estimated by considering the absence of interfering
peaks at the RT of each compound and based on the acquisition of two
MS/MS transitions for each analyte by selecting adequate precursor
and product ions.
LOQ - Established as the lowest concentration level validated with
satisfactory values of recovery and precision.
LOD - Estimated as the analyte concentration that produced a peak
signal of three times the background noise in the chromatogram, and it
Control of pesticide residues in food commodities has become a
was obtained by using a software option i.e., S/N ratio, referring this
requirement for compliance with the legislation, ensuring safety of
value to a S/N value of three.
the population and international and national trade.
Multi-residual methodologies capable to determine a large number
of pesticides simultaneously with satisfactory sensitivity and
To improve those methodologies by changing the analytical
selectivity are highly required.
determination using GC-MS/MS with QqQ analyzer, in order to
Combination of GCMS/MS, with ion trap analyzer approach has
improve sensitivity and selectivity, taking advantage of the possibility
been successfully validated for a large number of GC-amenable
of acquiring two MS/MS transitions for each compound.
pesticides in food ,water , soil samples,and etc.
Use of tandem mass spectrometry (MS/MS) with triple quadrupole
(QqQ) analyzer takes advantage of adequate precursor and
Optimization of the MS/MS method was performed for all
product ions selection.
pesticides using hexane standard solutions injected in the EI
Acquiring two transitions leads to a reliable confirmation of the
compound detected in sample.
For full scan spectra of each compound, the base peak of the
spectrum was selected as precursor ion.
Once the precursor ion was selected, different values of collision
Optimization of wide-scope multi-residue method using GC-
energy (between 4 and 40 eV) were tested to study the
MS/MS with QqQ analyzer for the determination of a large number of
fragmentation. The final purpose was to develop a method with two
organochlorines, organophosphorus pesticides.
Table shows the precursor and the product ions corresponding
to the quantitative and confirmative transitions monitored.
Optimum values of collision energy for most compounds were
found to be between 4 and 36 eV.
Retention time of GC-MS/MS chromatograms for OCs and OPs
pesticide reference standards, pesticides have been showed
within a wide range of retention times (5-20 min.) to better illustrate
the performance of the method.
The selectivity of the method was satisfactory and came from the
acquisition of two specific transitions for each pesticide.
GC-MS/MS chromatograms did not show the presence of
Acquisition of two transitions allows the simultaneous
quantification and confirmation of pesticides in only one injection,
as an alternative approach to the proposed elsewhere where one
injection with only one transition is used as a screening method
and a second injection, of only potentially positive samples, is
Fig-1 : A GC system (Agilent 6890N) equipped with an Autosampler
required for confirmation and quantification purposes.
(Agilent 7683) coupled to a Triple quadrupole (QqQ) mass
spectrometer Quattro Micro GC (RAB120 Waters).
GC Column: HP-5MS (30 m L, 0.25 mm i.d, 0.25 ?m
film thickness )
Oven programming : 50 C - 1 min.
25 C/min. - 150
10 /min. - 280 C (holding time 4 min.)
Injection volume: 1 µl
Injector temperature: 250 °C split less time of 1 min.
Carrier gas : Helium 99.999%, at a flow of 1.3 mL/min.
Interface temperature : 250 °C.
Mode : Electron impact, source temperature at
Collision gas: Argon 99.995%.
Dwell time / channel: 0.05 sec .
Reference gas : Heptacosa (perfluorotri-n-butylamine),
Software : MassLynx
Multi-residue method has been optimized for the simultaneous quantification and confirmation of around 22 pesticides.
Potential of GC-MS/MS with triple quadrupole analyzer has shown to be a key tool for the quantitative determination of this high number of
Selection of two transitions, one for quantification and one for confirmation, gives excellent selectivity and sensitivity.
M. I. Cervera & C. Medina & T. Portolés & E. Pitarch &J. Beltrán & E. Serrahima & L. Pineda & G. Muñoz & F. Centrich & F. Hernández. Multi-
residue determination of 130 multiclass pesticides in fruits and vegetables by gas chromatography coupled to triple quadrupole tandem
mass spectrometry, Anal Bioanal Chem (2010) 397:28732891.
2] Martínez Vidal JL, Arrebola Liébanas FJ, González Rodríguez MJ, Garrido Frenich A, Fernández Moreno JL (2006) Rapid Commun Mass
3] Garrido Frenich A, González-Rodríguez MJ, Arrebola FJ, Martínez Vidal JL (2005) Anal Chem 77:4640-4648.
4] Hernández F, Portolés T, Pitarch E, López FJ, Beltrán J, Vázquez C (2005) Anal Chem 77:7662-7672.
5] Torres, C.M., Pico, Y. and Manes, J.Determination of Pesticide Residues in Fruits and Vegetables, J. Chromatog. A, 1996; 754: 301-331.
Authors acknowledge ASIDE, Govt. of India and University of Agricultural Sciences, Dharwad, Karnataka, India for financial support.