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Determination of pesticide residues in coconut (Cocos nucifera Linn.) tree trunks by modified QuEChERS method and Ultra-High-Performance Liquid Chromatography coupled to Triple Quadrupole Tandem Mass Spectrometry


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A rapid and reliable method for the determination of 10 pesticide residues in coconut (Cocos nucifera L.) tree trunks after endotherapy treatments has been established. A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, using an homogeneous sample slurry and acetate buffer, followed by Ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. Under the best extraction conditions, the average recoveries for all pesticides spiked at 40, 80 and 200 µg kg−1 ranged from 70 to 93%, with RSD <10%. Intermediate precision, expressed as RSD, ranged between 3 and 6% for all compounds. Calibration curves showed a wide linear range between 10.0 and 1000.0 µg kg-1 for all compounds studied. Limit of quantification was established as 40.0 µg kg-1. The developed procedure was employed in the analysis of real coconut tree trunk samples obtained 45 h after pesticides application using endotherapy treatment. Concentrations of pesticides were between 44.7±5 and 938.3±20 µg kg-1. These results prove the translocation of pesticides in different heights, in the coconut tree trunk, from the application point. Imidacloprid presented the highest acropetal translocation and was found near the leaves at 61±6 µg kg-1.
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Determination of pesticide residues in coconut tree
trunks by modied QuEChERS method and ultra-
high-performance liquid chromatography coupled
to triple quadrupole tandem mass spectrometry
J. A. Ferreira,
V. Talamine,
J. F. Facco,
T. M. Rizzetti,
J. M. S. Ferreira,
F. A. Oliveira,
O. D. Prestes,
R. Zanella,
M. L. Martins,
M. B. Adaime,
S. Navickiene
and C. B. G. Bottoli*
A rapid and reliable method for the determination of 10 pesticide residues in coconut (Cocos nucifera L.)
tree trunks after endotherapy treatments has been established. A modied QuEChERS (quick, easy,
cheap, eective, rugged and safe) method, using an homogeneous sample slurry and acetate buer,
followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)
was developed and validated. Under the best extraction conditions, the average recoveries for all
pesticides spiked at 40, 80 and 200 mgkg
ranged from 70 to 93%, with RSD <10%. Intermediate
precision expressed as RSD, ranged between 3 and 6% for all compounds. Calibration curves showed a
wide linear range between 10.0 and 1000.0 mgkg
for all compounds studied. Limit of quantication
was established as 40.0 mgkg
. The developed procedure was employed in the analysis of real coconut
tree trunk samples obtained 45 h after pesticides application using endotherapy treatment.
Concentrations of pesticides were between 44.7 5 and 938.3 20 mgkg
. These results prove the
translocation of pesticides in dierent heights, in the coconut tree trunk, from the application point.
Imidacloprid presented the highest acropetal translocation and was found near the leaves at 61 6mgkg
1. Introduction
For millions of people living in coastal regions (tropical and
subtropical), the coconut tree has a large economical, social and
environmental importance, and it is classied as one of the
most important oil seed crops in the world. The coconut tree
(Cocos nucifera Linn.) is subject to attack by pests and diseases
causing production losses and aecting its quality. The appli-
cation of pesticides is still one of the most used practices to
control and prevent pests and diseases.
Traditional methods
such as spraying have been substituted by modern techniques
such as endotherapy by infusion or injection of pesticides into
the tree trunks, with such environment advantages as: (a) no
dispersion of plant protection products in the environment and
(b) safety for the public during and aer treatment. Endother-
apy is a pest control method for trees, which operates by xylem
or systemic injection of the protection products into the trunk.
It exploits the movement of pesticides applied in the tree trunk
so that the protection products can translocate into all the parts
of the plant.
Currently, many studies using endotherapy
techniques have been undertaken with pesticides and applied
in the plants.
In agriculture, endotherapy has been used
successfully and studied in tree species such as apple, pear,
cherry, avocado, palm (Elaeis guineensis), coconut, and even in
grape vines, becoming a new trend in modern
In the northeastern part of Brazil, dierent pesticides such
as 3-hydroxy-carbofuran, carbendazim, carbofuran, carbo-
sulfan, cyproconazole, difenoconazole, imidacloprid, thiaben-
dazole, thiamethoxam, thiophanate-methyl and spirodiclofen
are mixed and used in order to control the pests and diseases in
the coconut crop.
On the other hand, there is no information
if endotherapic treatments are eective as a method of pest and
disease control in coconut trees or if the residues could
contaminate the products and consumers above the limits
established by sanitary agencies in the European Union (EU)
and Brazil.
The literature reports the use of radioactively labeled pesti-
cides for studies of translocation. However, research involving
radiolabeled pesticides involves bureaucratic issues and it is
Instituto de Qu´
ımica, Universidade Estadual de Campinas, POB 6154, 13083-970
Campinas, SP, Brazil. E-mail:
Departamento de Engenharia Agronˆ
omica, Embrapa Tabuleiros Costeiros, Av. Beira
Mar, no 3250, 49025-040 Aracaju, SE, Brazil
Departamento de Qu´
ımica, Universidade Federal de Santa Maria, 97105-900 Santa
Maria, RS, Brazil
Departamento de Qu´
ımica, Universidade Federal de Sergipe, Av. Marechal Rondon
s/n, 49100-000 S˜
ao Crist´
ao, SE, Brazil
Cite this: DOI: 10.1039/c5ay00323g
Received 5th February 2015
Accepted 8th April 2015
DOI: 10.1039/c5ay00323g
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more dicult to perform, because it is necessary to isolate the
work area (environmental problem), the number of available
radiolabeled pesticides is limited, trained professionals are
required, and it is an expensive work due to the controlled
acquisition and discarding of the radiolabeled pesticides.
In this work, unlabeled pesticides were injected in coconut
tree trunk in order to know if pesticides translocate in the
xylem. For this a new method of sample preparation for the
coconut tree trunk was developed using the Quick, Easy,
Cheap, Eective, Rugged and Safe(QuEChERS) method for
extraction, rst introduced by Anastassiades et al. in 2003.
QuEChERS is a well-established method for the analysis of
multi-class and multi-residue analysis of pesticides in dierent
matrices such as fruits and vegetables, emerging contaminants,
oils, meats and soils using chromatographic techniques.
Thus, QuEChERS was used for the rst time to determine
pesticides injected into tree trunks by endotherapy and for
quantifying the pesticides translocated for dierent distances
from the point of application. This method has many advan-
tages over the method reported by Ferreira et al.,
developed the rst methodology for determining ve pesticides
applied in treatment of coconut palm trunks using matrix solid-
phase dispersion (MSPD) with determination by liquid chro-
matography with an diode array detection (HPLC-DAD). The
main advantages of QuEChERS over MSPD are high recovery for
pesticides having a wide range of polarities, faster analysis and
use of smaller amounts of organic solvent.
The extracts were analyzed by ultra high performance liquid
chromatography-tandem mass spectrometry (UHPLC-MS/MS)
to guarantee better selectivity and detectivity.
2. Experimental
2.1. Chemicals and solvents
The certied standards employed for pesticide analysis were
carbendazim, carbofuran, 3-hydroxy-carbofuran (3-OH-carbo-
furan), carbosulfan, cyproconazole, difenoconazole, spi-
rodiclofen, imidacloprid, thiabendazole, thiamethoxam and
thiophanate-methyl, all acquired from Dr Ehrenstorfer (Augs-
burg, Germany). 3-OH carbofuran is a metabolite of carbofuran.
Due to the toxicity of this compound, we considered relevant the
evaluation of consumer exposure and risk.
The standards were
of at least 95% purity. The class, chemical group, toxicological
class and chemical structures of the pesticides used in this
study are shown in Table 1.
The HPLC grade solvents acetonitrile and methanol were
from Mallinckrodt (Phillipsburg, USA) and glacial acetic acid
was from J. T. Baker (Pennsylvania, USA). Ultrapure grade LC
water was obtained by purication of distilled water through a
Direct UV3® gradient system from Millipore (Molsheim, USA)
and used for the preparation of buers, mobile phase and other
reagents. Anhydrous sodium acetate (NaOAc), anhydrous
magnesium sulphate (MgSO
) and sodium chloride (NaCl), all
reagent grade, were purchased from Merck (Darmstadt,
Primary secundary amine (PSA) and Bondesil C
(particles of 40 mm) were obtained from Agilent Technologies
(Wilmington, USA). Polypropylene centrifuge tubes were from
Sarstedt (N¨
umbrecht, Germany), using 50 mL ones for initial
extractions and 15 mL ones for the dispersive solid-phase
extraction (d-SPE) step.
2.2. Preparation of standard solutions
Individual stock solutions (1000 mg L
) were prepared in
dierent solvents (ethyl acetate for carbendazim and spi-
rodiclofen; methanol for thiophanate-methyl, carbofuran,
cyproconazole, carbosulfan and thiabendazole; acetone for
difenoconazole, thiamethoxam and 3-OH-carbofuran;
dichloromethane for imidacloprid). A mixture with all 11
pesticides was prepared in acetonitrile at 10 mg L
of each
pesticide. The stock and working solutions were stored at
18 C until needed. The working solutions were used for the
preparation of matrix-matched solution within the concentra-
tion range of 10.01000.0 mgkg
and for recovery studies,
which used samples spiked before the corresponding extraction
procedure at concentrations of 40.0; 80.0 and 200.0 mgkg
the studied pesticides.
2.3. Instrumentation and apparatus
QL-901 and NT 825 centrifuge vortex mixers were from Nova
ecnica (S˜
ao Paulo, Brazil). A Sartorius CP-225 balance
ottingen, Germany), a Rotox 46 centrifuge from Hettich
(Tuttlingen, Germany), a PT 3100 Polytron Ultra Turrax (Luzern,
Switzerland), and aIKA® A11 basic, analytical mill (Staufen,
Germany) were used.
Chromatographic analyses were performed in an Acquity
UPLCsystem from Waters (Milford, USA) equipped with a
binary solvent delivery system, degasser, autosampler and
column heater. Chromatographic separations were performed
using an Acquity BEH C18 UPLC column (100 mm 2.1 mm),
with 1.7 mm particle size from Waters. MS/MS detection was
performed using a Xevo TQD tandem quadrupole mass spec-
trometer from Waters (Manchester, UK), coupled with an elec-
trospray ionization interface (ESI) operating in the positive ion
mode. The source parameters were: capillary voltage: 2.5 kV;
source temperature: 150 C; and desolvation gas temperature:
500 C, with nitrogen ow rates of 600 and 80 L h
for the cone
and desolvation gases, respectively. Analytical instrument
control, data acquisition and data treatment were performed by
the soware MassLynx (Micromass, Manchester, UK), version
4.1. Mobile phase components were: eluent A: ultrapure
water : methanol (98 : 2, v/v) containing 0.1% formic acid and 5
mmol L
ammonium formate and eluent B: methanol with
0.1% formic acid and 5 mmol L
ammonium formate. The
gradient was: B from 5% at 0 min changing linearly to 100% at
8.50 min returning to 5% at 8.51 min and maintained until
10.00 min when a new injection was made. The ow rate was
0.225 mL min
and the injection volume was 10 mL. Selected
reaction monitoring (SRM) experiments were conducted with a
dwell time of 10 ms for all pesticides. The transition of higher
intensity was used for quantication and the second most
intense was used for conrmation. Collision induced dissocia-
tion (CID) was performed using argon as the collision gas at a
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pressure of 4 10
mbar and ow-rate of 0.15 mL min
Optimization of the collision energy for each individual pesti-
cide was done by direct-infusion into in the MS. The precursor
and product ions that were monitored by retention time, and
the molar masses, cone voltage and collision energies in posi-
tive ESI mode used for quantication and conrmation of each
analyte studied are shown in Table 2.
2.4. Sample
The coconut-tree variety selected for development of the
method in this study was hybrid coconut Port-Bouet-121 (PB-
121) acquired by the Brazilian Enterprise for Agricultural
Research (EMBRAPA) and planted in the experimental eld in
Itaporangad'Ajuda, Sergipe, Brazil. A real PB-121 tree was used
to study the translocation of pesticides by endotherapy in the
experimental eld of the Sococo Agroind´
ustria da Amazˆ
u, Par´
a, Brazil. Both samples for the development of the
method and for analysis of real samples were without the use
of pesticides in the selected coconut trees. A manual drill with
0.8 cm diameter needle was used at a depth of 15 cm to open
the trunk of the coconut tree for pesticide injection. Coconut
bers (wood shavings) were collected in sterile plastic bags
and identied under the recommended conditions prior to
use. The samples were stored in a freezer at 17 Cuntil
Table 1 Description of the pesticides
Pesticides Class Chemical group Toxicological class Chemical structure
3-OH-carbofuran ——
Carbendazim Fungicide Benzimidazole Unlikely to present acute
hazard in normal use
Carbamate Highly hazardous
Carbamate Moderately hazardous
Cyproconazole Fungicide Triazole Moderately hazardous
Difenoconazole Fungicide Triazole Moderately hazardous
Imidacloprid Insecticide Neonicotinoid Moderately hazardous
Thiabendazole Fungicide Benzimidazole Slightly hazardous
Thiamethoxam Insecticide Neonicotinoid No information
Thiophanate-methyl Fungicide Benzimidazole Unlikely to present acute
hazard in normal use
Spirodiclofen Acaricide, insecticide Tetronic acid No information
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2.5. Preparation of sample
The samples were homogenized in a ceramic mortar with dry
ice to reduce oxidation. Aer, the crushed samples were dried in
an oven for 6 h at 45 C. This temperature ensures that pesti-
cides do not degradate. This step facilitate the grinding in an
analytical mill in order for the sample to become a powder. The
powder was then stored in asks at 17 C in a freezer until the
sample preparation step. A slurry was prepared by weighing 10 g
of powdered trunk and adding 30 mL of puried water in a
proportion 1 : 3 (m/v), with posterior homogenization in an
Ultra-Turrax processor.
2.6. Modied QuEChERS method
The extraction method comprised the following steps: a
representative 10 g slurry portion was weighed in a 50 mL PTFE
centrifuge tube and then 10 mL of acetonitrile with 1% (v/v) of
acetic acid was added. The tube was shaken in a vortex for 1
min. Then, 1.7 g of sodium acetate and 4 g of anhydrous
was vigorously shaken using a vortex mixer for 1 min. The tube
was then centrifuged (3400 rpm) for 8 min at 20 C. Four mL of
the supernatant (acetonitrile phase) were transferred to a 15
mL centrifuge tube containing 100 mg PSA, 500 mg C
and 600
mg MgSO
, and the tube was vortexed for 1 min. Aer that, the
extract was centrifuged again (3400 rpm) for 8 min at 20 C. The
extract was ltered through a 0.22 mmPTFElter and trans-
ferred into a vial and then diluted 1 : 4 (v/v) with ultrapure
water for the injection of 10 mL into the UHPLC-MS/MS system.
2.7. Trunk injection procedure
Pesticides were applied to a coconut tree trunk in the winter
of July 2014, with constant rainfall, temperature of approxi-
mately 25 C and humidity above 80%. Three samples of
coconut tree were collected in dierent height 15, 30, 50 and 60
cm above the injection points 45 h aer injection of pesticides.
To prepare the injection solution, 10 mL of each active ingre-
dients of the commercial pesticide formulations (3-OH-carbo-
sulfan, carbosulfan, carbendazim, carbofuran, cyproconazole,
difenoconazole, imidacloprid, spirodiclofen, thiamethoxam,
thiabendazole) were mixed with 10 g of thiophanate-methyl
diluted in 10 mL of water. The experiment was performed with
the hole made by the automatic drill in two opposite positions
of the stem. Using 10 mL of this mixture was injected in each
hole. Posteriorly, for each hole 20 mL of water was injected to
wash the syringe. Aer this procedure, all the holes were closed
with billets of green wood and to covered with natural tar to
avoid entrance of insects.
2.8. Method validation
In this study, the parameters limit of detection (LOD), limit of
quantication (LOQ), accuracy, precision, specicity and matrix
eect were considered. The analytical method validation was
carried out using SANCO guidelines (SANCO/12571/2013).
3. Results and discussion
For this study, pesticides that are widely used on coconut trees,
including insecticides, acaricides, nematicides, fungicides and
herbicides were selected.
For the analysis of components present in plant matrixes,
the most common modes of ionization in LC-MS/MS include
electrospray ionization with mass analyzers such as a triple-
quadruple. This technique permits additional structural infor-
mation and is a strategic approach to nd known constituents,
as well as to isolate the target compounds.
The optimization of the precursor and product ions were
carried out by the injection of 10 mL of the individual pesticide
solution directly into the mass spectrometer by infusion.
Dierent fragmentation voltages were applied and the optimal
voltages were between 19 V for thiamethoxam and 37 V for
difenoconazole. Collision energies were investigated and
ranged from 10 eV for 3-OH-carbofuran to 60 eV for difenoco-
nazole. The most intense transition was used as for quanti-
cation while the second most intense transition was used for
conrmation. These parameters are presented in Table 2.
Compared to conventional HPLC, UHPLC systems operate at
higher pressures and use sub-2 mm packings in the columns,
Table 2 Mass spectrometer parameters for pesticides in the positive ESI mode
Molar mass
(g mol
Quantication transition
Voltage cone
Conrmation transition
3-OH-carbofuran 3.94 237.2 238.0 > 163.0 (16) 25 238.0 > 181.0 (10)
Carbendazim 3.11 191.2 192.1 > 132.1 (28) 24 192.1 > 160.1 (18)
Carbofuran 5.14 221.3 222.1 > 123.0 (16) 25 222.1 > 165.1 (16)
6.49 291.8 292.2 > 70.2 (18) 27 292.2 > 125.1 (24)
Difenoconazole 7.31 406.3 406.0 > 111.1 (60) 37 406.0 > 251.1 (25)
Imidacloprid 3.62 255.7 256.1 > 175.1 (20) 23 256.1 > 209.1 (15)
Thiabendazole 3.45 201.2 202.0 > 175.2 (25) 42 202.0 > 209.1 (30)
Thiamethoxan 3.14 291.7 292.2 > 132.0 (22) 19 292.2 > 211.2 (12)
Thiophanate-methyl 5.04 342.4 343.2 > 151.0 (21) 23 343.2 > 311.1 (11)
Spirodiclofen 7.98 411.2 411.2 > 71.2 (13) 22 411.2 > 313.0 (13)
Cyproconazole isomers.
Collision energy (eV) is given in parentheses.
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which decrease analysis time and increase peak capacity,
repeatability and detectability. Due to this, reversed phase
UHPLC-MS/MS was the method of choice for this work.
Although all pesticides used in this study were ionized in ESI
(+), the option of maintaining the mobile phase to detect ana-
lytes in both ESI (+) and ESI () was chosen in case of the need
to insert and validate other pesticides with this methodology.
3.1. Sample preparation and optimization of the extraction
Normally, for plant tissues, during the step of sample prepara-
tion for posterior chromatographic analysis, dissolution of the
analytes in a suitable solvent occurs as well as removal from the
solution of interfering compounds derived from biochemical
properties of the plant. Dissolution ruptures the cells within the
tissue matrix, increasing the surface area and the interactions
between solvent and matrix in the extraction process.
Generally, for vegetables and fruits, cryogenic milling with
dry ice is used in order to minimize degradation and improve
The coconut tree trunk has high oxidative
instability and the ber of the coconut is very dense, making the
process of milling more dicult. To facilitate ber disruption,
the sample must be completely dry, to eliminate water and
increase the surface area. Therefore, dry ice was homogenized
with the sample, which was then submitted to drying in an oven
at 45 C for 6 h, followed by grinding until the sample became a
Aer the sample was dried, a volume of water was added to
the sample to form a slurry in a proportion 1 : 3 (w/w), in order
to improve the extraction step of samples with low water
content. The advantage of this slurry is the standardization and
homogenization of the sample, the swelling of the stem and
better interaction of the sample with the solvent in the extrac-
tion step. In recent years, acetonitrile is the most widely used
extraction solvent for pesticide residues analysis. The main
advantages of using acidied acetonitrile as extraction solvent
are the lack of emulsions and no phase separation step.
The extraction procedure is oen the most critical step of a
method due to the diversity of substances that may be extracted
In this work, two procedures for pesticides
extraction were tested: the original QuEChERS method of
Anastassiades et al.
and the acetate buered QuEChERS
method modied by Prestes.
The original acetate buered
QuEChERS method was developed by Lehotay et al.,
extraction of the sample with acetonitrile containing 1% (v/v)
acetic acid and partitioning by adding MgSO
plus sodium
acetate (NaOAc) followed by a clean-up step using dispersive
solid phase extraction (d-SPE) with PSA and MgSO
. However,
proposed the following alterations of the Lehotay
et al.
method: (a) weight of the samples (from 15 g to 10 g); (b)
the volume of extraction solvent (from 15 mL to 10 mL); (c) mass
of salts and reagents in the partition step (from 6 g MgSO
1.5 g NaOAc to 4 g MgSO
plus 1.7 g NaOAc), and clean-up step
(from 50 mg PSA plus 150 mg MgSO
to 100 mg PSA plus 600 mg
); (d) change of the weight of C
adsorbent to 500 mg in
the clean-up step.
In this work, nal extracts from the original QuEChERS
method and the modied acetate buered QuEChERS method
were evaluated by drying the samples in a nitrogen gas ow (N
and verifying the formation of residues in the vial through
weighing. It was found that the amount of residue (co-extrac-
tives) in the vial formed by the original QuEChERS method was
higher than with the modied other method. Therefore, the
best alternative was to use the modied QuEChERS method.
Probably, the modications of the original procedure can be
more ecient for stems due to chemical characteristics of the
trunk tree, where the pesticides to be extracted are located
inside the bers and translocated through the xylem together
with transport of nutrients from the soil.
The trunk tree is
basically composed of holocellulose, pentosans, lignin, and
extractives as the minority substances: aromatic, aliphatic,
nitrogen containing compounds, glycosides, terpenes, steroids
and carbohydrates, among others, and can be removed by
solvents during the extraction procedure.
Thus, they can store
starches, oils, resins and crystals useful in any stress period.
The extraction method for pesticides used in this work becomes
suitable to extract pesticides from the bers of the tree trunk
due to some factors such as: (i) use of sodium acetate buer and
acetonitrile acidied with acetic acid to a pH of approximately 6
Table 3 Linear range, coecients of determination (r
) for analytical curves in solvent (acetonitrile), in the matrix extract (coconut tree trunk) and
the analytical curve equation of pesticides prepared from solutions spiked in blank coconut trunk
Pesticides Linear range (mgL
Equation y¼ax +bAcetonitrile Trunk coconut
3-OH-carbofuran 10 to 1000 0.9937 0.9984 12 424.9x+ 418.393
Carbendazim 0.9934 0.9979 10 891x+ 677.346
Carbofuran 0.9934 0.9982 26 973.6x1481.15
Cyproconazole 0.9965 0.9990 12 927.7x+ 560.555
Difenoconazole 0.9917 0.9976 12 976.1x+ 2016.34
Imidacloprid 0.9978 0.9989 3367.69x71.2287
Thiabendazole 0.9950 0.9972 16 979.2x+ 4129.62
Thiamethoxam 0.9953 0.9987 3232.65x182.052
Thiophanate-methyl 0.9957 0.9989 62.2367x11.0491
Spirodiclofen 0.9924 0.9920 2661.42x+ 224.469
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to prevent degradation of analytes sensitive to pH such as car-
bosulfan, carbendazim and thiabendazole; (ii) use of larger
amounts of PSA removal of sugars and fatty acids, smaller
organic acids, lipids and some pigments, (iii) use of C
remove lipids, sterols, long chain fatty compounds and other
non-polar interferences. Furthermore, the increase in MgSO
removes water from the organic phase, and forms a visible layer
of extractives in the bottom of the tube aer
3.2. Validation of the method
Validation of the method developed was according to the
procedure described in item 2.6. For all analytes in both curves,
detector response was linear with coecient of determination
) higher than 0.99 and residuals lower than 20% (Table 3).
In the stem matrix, detector saturation was not a problem
because samples were diluted ve times. Fig. 1 shows a
representative chromatogram obtained aer injection of
blank coconut trunk spiked at 200 mgkg
with the selected
pesticides. Analyte selectivity was ensured because the blank
extracts presented no interferences for the quantication and
conrmation transitions at the retention time of each
In this work, the limits of quantication and detection of the
method was dened as the analyte quantity for which the
relative standard deviation and recoveries of the analyses
reached a preestablished level. The values of LOD and LOQ of
the method were 12.1 and 40.0 mgkg
, respectively, for all
compounds. These values were obtained experimentally when
the pesticides were spiked into blank matrices at the 40 mgkg
level for all pesticides. This provided recoveries between 70 and
120% with RSD 20%. The choice of representative spiked levels
of pesticides were carried out considering the values found in
real samples, the physicalchemical characteristics of the
pesticides and the matrix (coconut tree trunk), which is a
complex matrix dicult to analyze.
The results showed recovery values between 70 to 93%, with
RSD #10% for three concentration levels. In the evaluation of
intermediate precision, values of recovery ranged from 86 to
113% and RSD
values were less than 6%, which are lower
than the recommended values (RSD #20%). These values can
be observed in Table 4. Therefore, the developed method is
suitable for quantifying pesticides in coconut tree trunks.
However, the experiments showed that was not possible to
analyse/validate carbosulfan in coconut tree trunk samples.
The sample processing step and extraction by the new buered
QuEChERS method were not sucient for carbosulfan anal-
ysis. Some studies suggest that this compound is easily
hydrolyzed to carbofuran and 3-OH-carbofuran under acidic
In complex matrices, such as plants, fruits and vegetables,
the number of ions formed in MS can be lower due to ion
suppression, or increased, resulting in a corresponding nega-
tive or positive matrix eect, respectively. In LC-MS/MS, the
matrix eect (ME) is usually caused by interferences of the
Table 4 Recovery, relative standard deviation (RSD) and matrix eect of pesticides prepared from solutions in acetonitrile (n¼3) and the
coconut tree trunk matrix eect (n¼3)
Spiked level (mgkg
40 80 80 200
Matrix eect (%)RRSD (%) RRSD (%) RRSD
(%) RRSD (%)
3-OH-carbofuran 80 3913 104 690326%
Carbendazim 73 785687680755%
Carbofuran 72 481592477622%
Cyproconazole 85 38759638827%
Difenoconazole 91 2905916894 +25%
Imidacloprid 79 1914 102 58845%
Thiabendazole 70 675387473653%
Thiamethoxam 76 2927 102 490950%
Thiophanate-methyl 82 7909 113 48410 47%
Spirodiclofen 91 9935865895 +36%
i.p. ¼intermediate precision.
Fig. 1 UHPLC-MS/MS chromatogram for the extract of coconut tree
trunk pesticides spiked at 200 mgkg
with the following compounds:
(1) carbendazim; (2) thiamethoxam (3) thiabendazole (4) imidacloprid
(5) 3-OH carbofuran (6) thiophanate-methyl (7), carbofuran (8)
cyproconazole (9) difenoconazole (10) spirodiclofen.
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matrix and components in the extract that compete in the
ionization process at the ion source when eluting at the same
retention time as the analyte.
The matrix eects can be
considered low (020%), medium (2050%) and strong
($50). Above 20%, it is necessary to use certain methods to
overcome the inuence of the matrix on the analytes.
The ME varied from 55% (strong signal suppression) to
+36% (increase of average signal), demonstrating the impor-
tance of use matrix-matched calibration. The dilution associ-
ated to the clean-up process is one of the ways to reduce matrix
eects. The assessment of values of the matrix eects showed
that some analytes, such as carbendazim, thiabendazole, thia-
methoxam and thiophanate-methyl, showed strong signal
suppression while spirodiclofen a showed strong signal
increase. Values of ME are presented in Table 4.
3.3. Application to real samples
Aer validation of the analytical methodology, the method was
applied to analyze samples from coconut tree trunks. In order to
check if the UHPLC-MS/MS was in the same conditions as
during the validation step, a matrix-matched calibration, a
reagent blank, a matrix blank and a spiked blank sample at 80
were evaluated before starting the analyse.
In samples collected aer application by trunk injection,
the pesticide levels found in the coconut tree trunk 15 cm
above the injection point had values for thiamethoxam, car-
bendazim, thiabendazole and imidacloprid above the linear
working range (1000 mgkg
). For carbofuran, difenoconazole,
spirodiclofen, 3-OH-carbofuran and cyproconazole, the values
were 343.9 10; 253.2 20; 434 20; 72.3 10 and 938.3 20
, respectively. The pesticide levels found in the coconut
tree trunk 30 cm above injection point had values for thiame-
thoxam of 554.6 8mgkg
, for carbofuran of 62.3 3mgkg
imidacloprid of 267.8 16 mgkg
and cyproconazole of 131.6
. 3-OH-carbofuran, spirodiclofen, difenoconazole,
thiabendazole, carbendazim were detected, but not quantied,
because they were below the limit of quantication. The
pesticide levels found in the coconut tree trunk 60 cm above
the injection point had values for thiamethoxam of 127.8 0.5
and for imidacloprid of 44.7 5mgkg
. Cyprocona-
zole was detected, but below the LOQ. The only pesticide found
near of leaves 45 hours aer injection was imidacloprid. It has
demonstrated good acropetal translocation in 45 h in the
coconut tree trunk had value for 61 6mgkg
. The chro-
matogram obtained for the extract of coconut tree trunk
pesticides in samples 15 cm above point application can be
seen in Fig. 2 and the results of acropetal translocation of
pesticides at all heights 45 h aer injection of pesticides are
shown in Fig. 3.
According to the octanolwater partition coecient (K
the pesticides studied, the results showed the acropetal
translocation of the majority of pesticides, except for thio-
The lipophilic ones with log K
such as cyproconazole, difenoconazole and spirodiclofen,
presented high concentrations. Pesticides with log K
between 0 to 3, such as 3-OH-carbofuran, carbendazim, car-
bofuran, thiabendazole and imidacloprid were found/quanti-
ed. Thiophanate-methyl was not found at any height in the
coconut tree trunk, probably because, in plants and in the
environment, thiophanate-methyl was metabolized to carben-
dazim. Thiamethoxan was the only hydrophilic pesticides
(log K
0.13) used that showed mobility in the phloem/
xylem. Spirodiclofen was the only non-systemic pesticides
applied and even then showed the translocation of 15 cm above
the injection point. These results suggest two main possibili-
ties: pesticides need more than 45 h to translocate or, alter-
natively, the pesticides require an adjuvant to potentiate the
In contrast, despite all the benets of endotherapy treat-
ment, little is known regarding the distribution of liquids
within woody plants and more research is needed to explore
their benecial eects.
As pesticide uptake research
requires both chemical and biological expertise, a close co-
operation between chemists and plant scientists, combined
with modern analytical techniques, is necessary to account for
the complex interactions between pesticides and the uptake
process in plants.
Fig. 3 Results of acropetal translocation of pesticides at dierent
heights (15, 30, 60 and 50 cm) in coconut tree trunks above the
injection points 45 h after injection of pesticides. The working range
used was 40 to 1000 mgkg
Fig. 2 UHPLC-MS/MS chromatogram for the extract of coconut tree
trunk pesticides in samples 15 cm above point application compounds:
(1) thiamethoxam; (2) carbendazim (3) thiabendazole, (4) imidacloprid,
(5) 3-OH-carbofuran, (6) carbofuran, (7) cyproconazole, (8) difeno-
conazole, (9) spirodiclofen.
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4. Conclusions
The modied QuEChERS method has been evaluated as the
extraction method for the determination of pesticide residues
applied by endotherapy in the coconut tree trunk with deter-
mination of the nal extract using UHPLC-MS/MS. The results
showed quite good analytical performance in terms of precision
and recovery, showed adequate linearity and low LOQ. The
present work could be used as an add on-method,i.e.,
allowing new pesticides to be constantly included without
needing to modify the method or to optimize for analysis of
pesticide residues in other monocot plants (from the same
biological family).
This study becomes important because it allows under-
standing if the pesticides can translocate to products derived
from coconut tree which have signicant nutritional value as
foods, such as fruit and sap. Furthermore, this method may be
used to evaluate whether it is possible to use another applica-
tion procedure as a secure alternative to endotherapy treatment
for the coconut tree trunk, to eliminate the pests and diseases of
This study provided innovative results showing the eciency
of the extraction method and analysis that contribute to the
knowledge of the process of translocation of pesticides aer
endotherapy treatment. This technique can become an impor-
tant tool for the application of pesticides, minimizing envi-
ronmental and farmer exposure, as well as substituting
techniques as use of radioactively labeled pesticides, to follow
ecacy as well as substituting the spraying procedure. It should
also be noted that the endotherapy treatment is protected from
the sun and rain.
This research was supported by FAPESP 2012/18318-4, INCT
ıtica-FAPESP 2008/57805-2 and CNPq 573672/2008-3.
The authors wish to thank Prof. Marco Aurelio De Paoli for
helpful comments, Prof. Carol H. Collins for language assis-
tance and Sococo Agroind´
ustria da Amazˆ
onia, mainly Dr Paulo
Lins for logistics and facilities.
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... Coconut palm (Cocos nucifera L.) is one of the major perennial crops with high commercial value [8]. In tropical countries, such as Brazil, this palm has an important role in culinary and industrial purposes [9]. However, several factors can reduce the crop yield, such as pest infestation [8]. ...
... Pesticide determination in wood and wood-based products is of considerable interest due to the problems associated with removal or recycling of wood waste, the contamination of indoor air, and manufacture of consumer products [11]. The few methods available for the determination of pesticide residues in wood matrices are mainly based on solid-liquid extraction [8][9][10]. Matrix solid-phase dispersion (MSPD) is a widely employed technique in trace contaminants preconcentration due to its simplicity, minimal cost, and low consumption of reagents [12][13][14]. ...
... In MSPD, the adsorbent material is very important because it determines the extraction efficiency and selectivity. To date, several commercial materials [9,10,14,15], as well as different MOFs [6,13,16,17] have been applied as MSPD sorbents for recovery of multiclass pesticides in various sample types. However, the recoveries of some analytes were not satisfactory in some cases. ...
... %ME values higher or lower than zero indicate the presence of signal enhancement or suppression in comparison with the instrumental response observed in procedural blank (Scordo et al., 2020). The matrix effects can be considered low (±0-20%), medium (±20-50%) and strong (≥±50%) (Ferreira et al., 2015). ...
... The highest matrix effects were found in white wine for carbendazim with − 47% and fluazifop p-butyl with 43%, while for red wine for carbendazim with − 48% and chlorpyriphos with − 45%. Previous study has reported strong signal suppression for carbendazim (-55%) (Ferreira et al., 2015). In conclusion, the matrix effect results, underline the importance of the use of matrix-matched calibration curves to overcome quantification accuracy problems in a single step. ...
In this research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction procedure and Ultra-High Performance Liquid Chromatography-Orbitrap-Mass Spectrometry (UHPLC-Orbitrap-MS), were combined to obtain a sensitive and rapid method for the determination of multiclass pesticides in white and red wines. The optimization strategy involved the selection of buffering conditions, by applying different QuEChERS procedures and sorbents for the cleanup step in order to achieve acceptably high recoveries and low co-extractives in the final extracts. Identification was based on both accurate mass and retention time, while further confirmation was achieved by MS fragmentation. The method was evaluated in terms of linearity, recovery, precision, limit of detection (LOD) and quantification (LOQ), matrix effects (ME) and expanded uncertainty. The validated method was successfully applied to real samples (home-made and commercial) revealing the presence of two selected fungicides, in relatively low levels compared to the MRLs defined by the EU for vinification grapes.
... But more sensitive results can be obtained with LC-MS/MS in spite of strong chromatographic and mass spectrometric interferences caused by coeluting matrix-compounds, as tebuconazole is a highly polar compound. Ferreira et al. (2015) and Ferreira et al. (2016) developed a method for multi-residue determination of pesticides in coconut trunk and in coconut water and pulp following QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safety) extraction method (Anastassiades, Lehotay, Stajnbaher, & Schenck, 2003) and LC-MS/MS. However, no studies have been done on tebuconazole method validation in coconut matrix and the persistence of tebuconazole in coconut water, kernel and leaves after root feeding which is the preferred mode of pesticide application by coconut farmers. ...
... Residues were below quantifiable level in coconut kernel and water in 1st and 3rd day samples but was below quantification limit afterwards. Ferreira et al. (2015) studied recoveries from 40 μg kg − 1 of coconut tree trunk sample and reported concentrations of pesticides between 44.7 ± 5 and 938.3 ± 20 μg kg − 1 and proved the translocation of pesticides in different heights in the coconut tree trunk after trunk injection treatment. The researchers also reported acropetal movement of imidacloprid near the leaves at 61 ± 6 μg kg − 1 . ...
A method was validated for determining tebuconazole residues in coconut water, kernel and leaves using Liquid chromatography-Mass spectrometry/Mass spectrometry (LC–MS/MS) with electro spray ionization in positive ion mode. Samples were extracted with acetonitrile and subsequent clean-up was done using dispersive solid phase extraction. Recovery ranged between 70 and 114.39 % and the RSD was between 0.64 and 10.24 %. Root feeding studies with tebuconazole @ 5 and 10 mL/100 mL of water/tree revealed the presence of tebuconazole residues in coconut leaves until three days after treatment but dissipated to below quantifiable limit on 5th day at single dose while the residues went below quantifiable limit after 10 days at double the dose. Residues were below quantifiable limit in coconut water and kernel until three days. Data obtained from the study were used for estimating the risks associated with the exposures to tebuconazole residues in coconut.
... Despite this, SANTE has been the most employed guideline for pesticide residues analysis validation in food using QuEChERS and liquid chromatography determination. This can be evidenced since SANTE was used in most publications in this area in the recent years (Paz et al. 2015;Golge and Kabak 2015;Andrade et al. 2015;Christia et al. 2015;Abad-Fuentes et al. 2015;Lichtmannegger et al. 2015;Botero-Coy et al. 2015;Lopes et al. 2015;Ferreira et al. 2015;Martins et al. 2016;Bernardi et al. 2016;Vázquez et al. 2016;Mol et al. 2016). ...
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A fast ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) method was developed for quantitative determination of pesticide residues in pear. A fast modified acetate QuEChERS method without clean-up was used for sample preparation. Validation was performed according to SANTE guideline. Matrix effect results were significative for most part of compounds and thus a matrix-matched calibration was employed. The linear range of the method was from 2.5 to 100 μg kg−1. Recoveries were between 70 and 120% with precision ≤ 20%. Limit of quantification was 2.5 μg kg−1 for most compounds. Uncertainty results ranged from 22 to 49%. In real sample analyses, 21 compounds were quantified in concentrations between 3.3 and 1427 μg kg−1. Method proved to be simple, robust and effective to be applied in routine analysis.
Quantitative determination of targeted and untargeted pesticide residues from food products is very important for the assessment of safety of the food products. In the present work, a simple, selective and sensitive method based on liquid chromatography atmospheric pressure chemical ionization high energy collisional dissociation high-resolution tandem mass spectrometry (LC-APCI-HCD-HRMS/MS) for quantification of 19 priority organophosphorus and carbamate pesticides and 10 untargeted pesticides from coconut milk samples was developed and validated. The pesticide residues were extracted by solvent partition followed by dispersive solid-phase extraction clean-up and quantified by LC-APCI-HRMS/MS technique. The method showed the linearity for targeted pesticides in the range of 0.5-1000 ng/g with a limit of detection of ranging 0.5-5 ng/g and limit of quantification of ranging 1-10 ng/g measured at 3:1 and 10:1 signal to noise ratios, respectively. The untargeted pesticide residues were quantified by the response factor method. The method was validated for intraday and interday precision, which was less than 15%. The recovery of the analytes varied between 82-117%, and the developed method was applied for the analysis of the coconut milk samples. The analyzed samples showed the presence of quinalphos, malathion, and methiocarb at concentrations of 4.55, 5.54, and 206.99 ng/g.
As one of the main fungicides for the apple leaf disease control, thiophanate‐methyl (TM) mainly exerts the fungicidal activity in the form of its metabolite carbendazim (MBC), whose dissipation kinetics is very distinct from its parent but was paid little attention. The aim of this work was to investigate the dissipation kinetics of TM and its active metabolite MBC in apple leaves using a modified QuEChERS‐UPLC‐MS/MS method. Results showed TM and MBC could be quickly extracted by this modified QuEChERS procedure with the recoveries of 81.7%‐96.5%. The method linearity was in the range of 0.01‐50.0 mg kg‐1 with the quantification limit of 0.01 mg kg‐1. Then this method was applied to the analysis of fungicide dissipation kinetics in apple leaves. Results showed the dissipation kinetics of TM for the test in three months can be described by the first order kinetics model with the DT50 (dissipation half‐life) range of 5.23‐6.03 days and the kinetics for MBC can be described by the first order absorption‐dissipation model with the Tmax (time needed to reach most concentration) range of 4.78‐7.09 days. These models can scientifically describe the behavior of TM and MBC in apple leaves, which provide necessary data for the scientific use.
Full-text available
This article presents an overview of analytical methods for the analysis of pesticide (new-generation) and related compounds in the last 5 years, which updates the previous one. Pesticides included in this group display almost no change, but the evolution of analytical techniques is important. In general, new pesticides are now included in multiresidue methods with generic sample treatment methodologies being able to extract as many pesticide classes as possible. However, this article focuses not only on these commonmultiresidue methods but also on specific methodologies as single-residue methods for the analysis of new-generation pesticides. The most widely used detection technique for the determination of pesticides is mass spectrometry (MS) combined with gas chromatography (GC) and/or liquid chromatography (LC). However, the advances in immunoassays, biosensors and other techniques are also included. Finally, the future perspectives and the trends for pesticide residue analysis in food and environmental matrices are outlined.
Current methods employed for the analysis of the chemical composition of solid matrices (such as plant, animal or human tissues, soil, etc.) often require many sample treatment steps, including an extraction step with exclusively dedicated solvents. This work describes an optimized analytical setup in which the extraction of a solid sample is directly coupled to its analysis by high-performance liquid chromatography. This approach avoids (i) the use of pumps and valves other than those comprising the HPLC instrument, (ii) the use of solvents other than those of the mobile phase and (iii) the need to stop the mobile phase flow at any time during the full analytical procedure. The compatibility of this approach with the direct analysis of fresh tissues (leaves, stems and seeds of four plant species with dissimilar chemical compositions) was successfully demonstrated, leading to the elimination of sample preparation steps such as drying, grinding, concentration, dilution, and filtration, among others. This work describes a new, simple, and efficient green approach to minimize or eliminate sample treatment procedures. It could be easily applied for quality control of plant materials and their derived products through chromatographic fingerprints and for untargeted metabolomic investigations of solid matrices, among other applications.
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The evaluation of analytical methods for determining the level of residues and contaminants in food samples is a continuing need. To improve this evaluation, it is necessary to investigate different extraction procedures and conditions. A 23 factorial design was applied to establish an analytical method for determining pesticide residues in wheat by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Factors that influence the recovery of compounds, such as agitation and different processes of partition and cleanup, were investigated. Extracts were analyzed by LC-MS/MS with electrospray ionization in a triple quadrupole system. The use of ultrasonic agitation in the extraction step, deep freezing for the partition step, and C18 cleanup provided significantly better recoveries for most of the compounds evaluated. Assessment of each factor as well as interactions between factors allowed for a more effective evaluation of the parameters involved in the development of analytical methods. The validation results were satisfactory, since the method presented linearity (r 2) >0.99 for all compounds, the matrix effect ranged from 3 to 97 % and was corrected by matrix-matched standards, and recoveries ranged from 70 to 120 % with RSD ≤20 % for the spike levels of 10 and 100 μg kg−1. The method limit of detection and limit of quantification ranged from 3.3 to 6.7 μg kg−1 and from 10 to 20 μg kg−1, respectively, and the expanded uncertainty ranged from 15 to 32 %. The proposed method met the criteria for determination of 42 pesticides in wheat samples and was successfully tested in real samples.
Full-text available
In woody plants, xylem sap moves upwards through the vessels due to a decreasing gradient of water potential from the groundwater to the foliage. According to these factors and their dynamics, small amounts of sap-compatible liquids (i.e. pesticides) can be injected into the xylem system, reaching their target from inside. This endotherapic method, called "trunk injection" or "trunk infusion" (depending on whether the user supplies an external pressure or not), confines the applied chemicals only within the target tree, thereby making it particularly useful in urban situations. The main factors limiting wider use of the traditional drilling methods are related to negative side effects of the holes that must be drilled around the trunk circumference in order to gain access to the xylem vessels beneath the bark. The University of Padova (Italy) recently developed a manual, drill-free instrument with a small, perforated blade that enters the trunk by separating the woody fibers with minimal friction. Furthermore, the lenticular shaped blade reduces the vessels' cross section, increasing sap velocity and allowing the natural uptake of an external liquid up to the leaves, when transpiration rate is substantial. Ports partially close soon after the removal of the blade due to the natural elasticity and turgidity of the plant tissues, and the cambial activity completes the healing process in few weeks.
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Endemic fungal foliar diseases, such as leaf blight – LB [Lasiodiplodia theobromae (Pat.) Griffon and Maubl] and leaf verrucosis, or “lixa-pequena” – LP [Camarotela torrendiela Batista (Bezerra) and Vitoria], reduce the productivity of the coconut palm in Brazil. Damage arises from extensive necrosis of the leaflets, resulting in early abscission of basal leaves and fruit. In Brazil, fungicide terrestrial sprayings has not been a commonly employed practice for the control of coconut foliar diseases because it is not cost-effective, once requiring high-volume of fungicide spraying. Coverage gaps and extensive drift of chemicals can occur due to technological limitations of terrestrial spraying of the tallest mature trees and is further complicated by the peculiar architecture of the palms. The aim of this study was to evaluate the efficacy of systemic fungicides applied directly to the leaf axil of the coconut palm (variety Brazilian Green Dwarf of Jiqui) for the control of foliar diseases. During 2007–2010 and 2009–2012, two field plot experiments were conducted at distinct locations (farms) in the North Fluminense region. Two to 4-monthly applications of the fungicides to the leaf axil of cyproconazole (alone), cyproconazole plus azoxystrobin, cyproconazole plus trifloxystrobin, and flutriafol (alone) were efficacious in controlling coconut palm leaf diseases, resulting in a significant reduction of the LB severity and the number of necrotic LP lesions. When compared with the control treatment, significant increases in the total number of leaves per plant were observed for the most efficacious treatments after one year (2–4 leaves more) and after the second year (3–6 leaves more) after initiating the axillary applications of fungicides in both experiments. This trend continued even after the third year, when there was an average of 8 leaves more for the most efficacious treatment (27 leaves per plant) compared to control (19 leaves per plant) at the end of second experiment. The control of foliar diseases based on the results could ensure a significant increase in regional coconut production.
Full-text available
Monocrotophos (60 %), a systemic organophosphate insecticide, was injected into the trunk of coconut palms of 8-10 m height and 20 years of age at the rate of 20.0 ml per palm. The residue levels of monocrotophos In coconut water and kernel at various stages of nut development and different durations after ap- plication, measured by GLC, showed that the residues were below the tolerance limit of 0.2 ppm at 14 days after trunk injection.
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A method was developed using matrix solid-phase dispersion, together with liquid chromatography with ultraviolet diode array detector for determination of carbofuran, difenoconazole, β-cyfluthrin, spirodiclofen and thiophanate-methyl in stem of coconut palm. The best results were obtained using 2.0 g of stem, 1.6 g of Florisil as sorbent and cyclohexane:acetone mixture (4:1). The method was validated using stem samples spiked with pesticides at four concentration levels (0.05-2.0 μg/g). Average recoveries ranged from 70 % to 114.3 %, with relative standard deviations between 1.2 % and 19.2 %. Detection and quantification limits were in the ranges 0.02-0.03 and 0.05-0.1 μg/g, respectively.
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A multi-class, multi-residue method for the analysis of 13 novel flame retardants, 18 representative pesticides, 14 polychlorinated biphenyl (PCB) congeners, 16 polycyclic aromatic hydrocarbons (PAHs), and 7 polybrominated diphenyl ether (PBDE) congeners in catfish muscle was developed and evaluated using fast low pressure gas chromatography triple quadrupole tandem mass spectrometry (LP-GC/MS-MS). The method was based on a QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction with acetonitrile and dispersive solid-phase extraction (d-SPE) clean-up with zirconium-based sorbent prior to LP-GC/MS-MS analysis. The developed method was evaluated at 4 spiking levels and further validated by analysis of NIST Standard Reference Materials (SRMs) 1974B and 1947. Sample preparation for a batch of 10 homogenized samples took about 1h/analyst, and LP-GC/MS-MS analysis provided fast separation of multiple analytes within 9min achieving high throughput. With the use of isotopically labeled internal standards, recoveries of all but one analyte were between 70 and 120% with relative standard deviations less than 20% (n=5). The measured values for both SRMs agreed with certified/reference values (72-119% accuracy) for the majority of analytes. The detection limits were 0.1-0.5ngg(-1) for PCBs, 0.5-10ngg(-1) for PBDEs, 0.5-5ngg(-1) for select pesticides and PAHs and 1-10ngg(-1) for flame retardants. The developed method was successfully applied for analysis of catfish samples from the market.
Coconut water is a natural isotonic drink and a rich source of sugars, salts, vitamins, minerals and amino acids, and can be served as a beverage to quench thirst. Palm trees are often attacked by insects and/or pests, therefore reducing their productivity. In order to enhance coconut production, pesticides are often used. Thus, the main objective of this study is to propose a simple and efficient method for the determination of pesticide residues, from different chemical classes, in samples of industrialized and natural coconut water, using single-drop microextraction (SDME), followed by gas chromatography coupled to mass spectrometry (GC–MS). The extraction step using SDME was optimized and it was found that the best experimental conditions for 10 mL of samples were obtained using toluene as an extraction solvent; stirring time of 30 min at 200 rpm; drop volume of 1.0 μL; and acidification with HCl without salt addition. The chromatographic method was validated and good values were found for the figures of merit, with LOD ranging between 0.1 and 0.88 μg L− 1, and LOQ between 1.21 and 6.69 μg L− 1. The method was successfully applied to real samples of natural and industrialized coconut water, and the pesticides sulfotep, demeton-O, dimethoate, disulfoton, fenitrothion and malathion were determined at concentrations ranging from < LOQ to 12.1 μg L− 1. The proposed methodology presents high sensitivity and the capability for detecting and quantifying low levels of pesticides in coconut water samples.
In this study a multiresidue method for the determination of 24 pesticides in wheat, white flour and bran using gas chromatography coupled to mass spectrometry with negative chemical ionisation and selected ion monitoring (GC–MS (NCI–SIM)) was developed and validated. The QuEChERS method was used for the extraction of different pesticides. The method was validated evaluating the following parameters: linearity, limit of detention, limit of quantification, matrix effect as well as precision and accuracy, evaluating the percentage of recovery at four different spike levels. The linear range used in the calibration curves was from 1.0 to 100μgL−1 for wheat and 2.0 to 200μgL−1 for flour and bran, both with values of r2>0.99. The recoveries had been considered satisfactory presenting values between 70% and 120% with RSD
Background: This paper discusses U.S. agricultural pesticide use trends from 1964 to 2010 based on estimates developed from USDA surveys, and the influence of economic factors, agricultural policy, and pesticide regulation on aggregate quantities and mix of pesticides used. Results: Synthetic organic pesticide use grew dramatically from the 1960s to the early 1980s, as farmers treated more and more acreage. Use then stabilized, with herbicides applied to about 95% of corn, cotton, and soybean acres, annually. Subsequently, major factors affecting trends were: (1) changes in crop acreage and other economic factors, (2) use of new pesticides that reduced per-acre application rates and/or met more rigorous health and environmental standards, and (3) adoption of genetically engineered insect-resistant and herbicide-tolerant crops. Conclusion: The use of pesticides and other control practices responded to economic factors such as input and output markets and agricultural policies. Changing societal values toward pesticide risks and benefits profoundly affected pesticide policy, influencing the pesticides available for use, but only indirectly affecting aggregate quantities used. While the current pesticide regulatory process might have economic inefficiencies, it might be consistent with policy preferences held by much of the public-to reduce pesticide hazards rather than minimize regulatory costs.
This study addresses a current trend in chemical food safety control represented by an effort to integrate analyses of various groups of food contaminants/toxicants into a single, high-throughput method. The choice of optimal sample preparation step is one of the key conditions to achieve good performance characteristics. In this context, we investigated the possibility to expand the scope of the three multi-analyte extraction procedures employed earlier in other studies for rapid isolation of either pesticides or mycotoxins from plant matrices. Following procedures were tested: A - aqueous acetonitrile extraction followed by partition (QuEChERS-like method), B - aqueous acetonitrile extraction, and C - pure acetonitrile extraction. On the list of target analytes, we had 288 pesticides (including 'troublesome' acidic, basic and base-sensitive compounds) together with 38 mycotoxins (including all EU regulated ones and many 'emerging' toxins on the European Food Safety Authority (EFSA) list). The matrices selected for the experiments, apple baby food, wheat flour, spices and sunflower seeds, represented various composition categories in terms of moisture, fat and extractable compounds (e.g. pigments and essential oils) content. In preliminary experiments, acceptable recoveries (70-120%) for most of analytes were obtained by the analysis of spiked matrices, regardless which extraction procedure was used. However, when analysing dry samples with incurred pesticide residues/mycotoxins, the method C did not enable efficient extraction of some common contaminants. Procedure A, thanks to a higher matrix equivalent compared to the method B and relatively less pronounced matrix effects, enabled lower quantification limits for all analyte/matrix combinations, with the exception of polar mycotoxins and/or pesticides. Higher recoveries for the latter group of analytes could be achieved by the method B; on the other hand, extraction efficiency of non-polar pesticides from fatty matrix was rather poor by this method.