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Effect of household processing and unit to unit variability of azoxystrobin,acrinathrin and kresoxim methyl residues in zucchini

Ana Aguilera a,*, Antonio Valverde a, Francisco Camacho a, Mourad Boulaid a, Luis Garca-Fuentes b

a Pesticide Residue Research Group, Faculty of Experimental Sciences, University of Almera, 04120 Almera, Spainb Physical Chemistry Department, Faculty of Experimental Sciences, University of Almera, 04120 Almera, Spain

a r t i c l e i n f o

Article history:

Received 28 July 2011

Received in revised form

24 November 2011

Accepted 30 November 2011

Keywords:

Azoxystrobin

Acrinathrin

Kresoxim methyl

Zucchini

Household processing

Residues variability

a b s t r a c t

Residuelevels of azoxystrobin,acrinathrin and kresoxim methyl were determinedin zucchini grown in an

experimental greenhouse during a two weeks period in which repeated treatments with the three pesti-

cides were applied. Analysis wascarried outby usingethylacetate extraction andgas chromatography with

electron capture detection (GC-ECD). The maximum values of residues determined in the plantation were

1.87 mg/kg for azoxystrobin, 0.25 mg/kg for acrinathrin and 0.20 mg/kg for kresoxim methyl. The

applicationof threedifferent household processing(washing,peeling andcooking) and the studyofunit to

unit variability of these pesticides in zucchini were also carried out. The washing processing factors

resulted to be 0.3,0.2 and0.0 foracrinathrin, azoxystrobin andkresoxim methyl, respectively; whereasthe

peeling processing factors ranged between 0.0 and 0.1. The cooking processing factors were 0.9 for acri-

nathrin,1.1 forkresoxim methyland 1.4 forazoxystrobin, the average loss of water in the zucchini samples

during the cooking process being 36 %. The unit to unitvariability factors were also determined on six

different samples containing ten unprocessed fruits (units) each sample. In all cases, the unit to unit

variability factors obtained for the three pesticides ranged between 1.3 and 2.4.

2011 Elsevier Ltd. All rights reserved.

1. Introduction

The use of pesticides in commercial agriculture has led to an

increase in farm productivity, so that farmers can produce a wide

variety of agricultural commodities at a reasonably low cost. The

disadvantage of pesticide use is that residues remain on food

commodities where they contribute to the total dietary intake of

pesticides. For many years it has been assumed that treatments like

washing fruits and vegetables prior to consumption reduces the

amount of pesticide residues, but these approaches need experi-

mental conrmation (Coscoll, 1993). Several studies have exam-

ined the effect of processing to remove pesticide residues in fruits

and vegetables (Abou-Arab,1999; Burchat et al.,1998; Elkins,1989),but comparative data for the effects of common household prepa-

ration including washing, peeling and/or cooking on pesticide

residue levels are limited (Boulaid, Aguilera, Camacho, Soussi, &

Valverde, 2005; Chavarri, Herrera, & Ario, 2004; Fernndez-

Cruz, Villaroya, Llanos, Alonso-Prado, & Garca-Baudn, 2004;

Randhawa, Anjum, Ahmad, & Randhama, 2007).

Acrinathrin, (S)-a-cyano-3-phenoxybenzyl (Z)-(1R,3S)-2,2-

dimethyl-3-[2-(2,2,2-triuoro-1-triuoromethylethoxycarbonyl)

vinyl]cyclopropanecarboxylate, is an acaricide and insecticide

belonging to the family of synthethic pyrethroids. It has contact and

stomach action, and it is effective against a great range of

phytophagous mites and has high efcacy on the management on

thrips species on fruits trees, vines and vegetables (Tomlin, 2009).

Azoxystrobin, methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-

yloxy]phenyl}-3-methoxyacrylate, and kresoxym methyl, methyl

(E)-methoxyimino[2-(o-tolyloxymethyl)phenyl]acetate, are fungi-

cides of the strobilurin group with protective activity, mainly used

for the control ofOidium spp. on different vegetable crops, including

cucurbits (Lin y Vicente, 2009; Tomlin, 2009).During the last ten years, a number of papers describing

analytical methods for azoxystrobin, acrinathrin and kresoxim

methyl residues in foods have been published (Arrebola, Martinez

Vidal, Gonzalez-Rodriguez, Garrido-Fenich, & Snchez Morito,

2003; Economou, Botisti, Antoniou, & Tsipi, 2009; Sannino, Bolzoni,

& Bandini, 2004; Soler, James, & Pic, 2007; Taylor, Hunter, Lindsay,

& Le Bouhellec, 2002), but the literature on the behavior of these

three pesticides in fruits and vegetables is some more limited

(Garau, Angioni, Aguilera del Real, Russo, & Cabras, 2002; Martinez

Galera, Gil Garca, Rodriguez Lallena, Lpez Lpez, & Martinez Vidal,

2003; Rabolle, Spliid, Kristensen, & Kudsk, 2006).* Corresponding author. Tel.: 34 950015611; fax: 34950015008.

E-mail address: aaguiler@ual.es(A. Aguilera).

Contents lists available at SciVerse ScienceDirect

Food Control

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . co m / l o c a t e / f o o d c o nt

0956-7135/$ e see front matter 2011 Elsevier Ltd. All rights reserved.

doi:10.1016/j.foodcont.2011.11.038

Food Control 25 (2012) 594e600

mailto:aaguiler@ual.eshttp://www.sciencedirect.com/science/journal/09567135http://www.elsevier.com/locate/foodconthttp://dx.doi.org/10.1016/j.foodcont.2011.11.038http://dx.doi.org/10.1016/j.foodcont.2011.11.038http://dx.doi.org/10.1016/j.foodcont.2011.11.038http://dx.doi.org/10.1016/j.foodcont.2011.11.038http://dx.doi.org/10.1016/j.foodcont.2011.11.038http://dx.doi.org/10.1016/j.foodcont.2011.11.038http://www.elsevier.com/locate/foodconthttp://www.sciencedirect.com/science/journal/09567135mailto:aaguiler@ual.es

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The aims of this study were to evaluate the residue levels of

azoxystrobin, acrinathrin and kresoxim methyl in zucchini grown

in a plastic greenhouse and to assess the inuence on these resi-

dues of some household processes (washing, peeling and cooking).

Another objective of this work was to study the variation of the

residue levels of these pesticides in individual zucchini fruit units

versus composite samples and to compare the calculated vari-

ability factors with the default values usually considered for

consumer risk assessment (Suhre, 2000; World Health

Organization, 1997). The experimental design applied in this work

was similar to that previously used by Boulaid et al. (2005)to study

the residual behavior of pyrifenox, pyridaben and tralomethrin in

tomatoes.

2. Experimental

2.1. Chemical and apparatus

Acetone, ethyl acetate, cyclohexane and anhydrous sodium

sulfate (pesticide residue grade) were obtained from Panreac

(Barcelona, Spain). Certied standards of azoxystrobin (99.5%

purity), acrinathrin (98.0% purity) and kresoxim methyl (99.5%

purity) were supplied by Dr. Ehrenstorfer (Augsburg, Germany).Individual stock standard solutions of azoxystrobin, acrinathrin and

kresoxim methyl were prepared in acetone. Working standard

solutions for gas-chromatographic (GC) analysis were prepared by

suitable dilution of the stock standard solutions with blank

zucchini extracts.

The gas chromatograph was a Varian model 3800 (Walnut

Creek, CA,USA) equipped with a model 1079 injectionport, a model

8200 Cx autosampler, an electron capture detector (ECD), and a DB-

5MS fused-silica capillary GC column (J&W, Folson, CA, USA) of 30

m length, 0.25 mm internal diameter and 0.25 mm lm thickness.

The chromatographic conditions were as follows: detector

temperature, 300 C; injector temperature, 250 C; oven tempera-

ture program, 1 min at 60C, 25 C/min to 180 C, 5 C/min to

260 C, and hold for 29 min; carrier gas (helium) ow rate, 1.2 mL/min; makeup gas (nitrogen) ow rate, 30 mL/min; injection

volume, 1mL; and splitless time, 0.75 min. The retention times of

azoxystrobin, acrinathrin and kresoxim methyl in this column

under these GC conditions were 35.0, 23.1 and 16.7 min, respec-

tively. A Varian Star 4.5 Chromatography Workstation was used for

chromatographic data processing.

2.2. Greenhouse, treatments and sampling

The study was conducted in a 200 m2 experimental plot, inside

a commercial greenhouse located in Nijar (Almeria, Spain). The

zucchini plant density (variety Storrs Green) was approximately

10,000 plants/ha. Residue levels of azoxystrobin, acrinathrin and

kresoxim methyl were determined in zucchini of commercial size(90e150 g), during a period of time in which four consecutive

treatments were applied to the plantation. Zucchini plants,

receiving routine horticultural treatment, were rst sprayed with

an application solution containing 0.8 mL/L Ortiva (azoxystrobin

25%) at a recommended application rate of 200 g azoxystrobin/ha.

After two days, a secondtreatment with a mixture containing 0.4 g/

L Stroby (kresoxim methyl 50%) and 0.9 g/L Rufast (acrinathrin

7.5%) at the recommended applicationratesof 200 g/ha and 70 g/ha

of kresoxim methyl and acrinathrin, respectively, was applied. After

seven and nine days of the rst treatment, two new treatments

with a double dose were applied to the plantation. Authorized uses

and label instructions for application of these threeplant protection

products in Spain can be found at the Spanish Ministry of Agri-

culture web site (www.marm.es/es/agricultura/temas/medios-de-

produccion/productos-tosanitarios/registro ). It is important to

note that the pre-harvest intervals established in zucchini are 1 day

for Ortiva (azoxystrobin) and Rufast (acrinathrin), and 3 days for

Stroby (kresoxim methyl), being allowed multiple applications in

all the cases.

Samples were collected at 1, 2, 3, 4, 5, 7, 8, 9, 10, 12 and 14 days

after rst treatment. In all cases, the greenhouse samples consisted

of 50 mature fruits of zucchini (aprox. 6 kg) taken at random from

the experimental plot. Samples taken on treatments days were

taken just prior treatment. A number of blank zucchini samples

were collected prior rst treatment application. The days of treat-

ment and sampling, and the greenhouse samples designation are

summarized inTable 1.

The daily maximum/minimum/medium temperatures inside

the greenhouse during the study ranged between 23/13/19 and 30/

17/23 C, whereas the daily maximum/minimum/medium relative

humidity inside the greenhouse ranged between 50/31/40 and 90/

38/63%.

2.3. Sample preparation, processing and analysis

Immediately after picking, the greenhouse samples were put

into polyethylene bags and transported to the laboratory. From

each greenhouse sample, four subsamples of 10 mature fruits each

were obtained. The ten zucchini fruits from one of these four

subsamples were cut lengthwise in four equal parts, and the two

opposite parts from each zucchini fruit were mixed and chopped to

obtain the unprocessedsample A. The other two opposite parts

from each zucchini fruit were also prepared in the same way to

obtain the unprocessedsample B. The ten pieces of zucchini from

the second subsample were prepared in the same way, but two

opposite parts from each zucchini were peeled (without washing)

priormixing and chopping to obtain, in this case, the unprocessedsample C and the peeledsample. On the other hand, before being

chopped and mixed, the ten zucchini fruits from the third

subsample were intensively washed with tap water and further

dried with absorbent paper obtaining the washed sample. Inaddition, immediately after preparing the unprocessed samples A

and B, a 250 g aliquot of each one was cooked to obtain the cor-

responding cooked samples A and B. The cooking process was

carried out into 1 L glass jars by heating at 100 C for 30 min (after

a period of 30 min, approximately, from room temperature to

100C) with continuous magnetic agitation. In all cases, the lost of

water produced during the cooking process was determined, water

being reconstituted in the cooked samples before analysis. A

scheme of the preparation and processing procedure applied to

Table 1

Pesticide treatments and sampling schedule of zucchini fruit with sample

designation.

Day Treatment Sample identicationa

0 Azoxystrobin, 200 g a.i./ha S0 (control sample)

1 S1

2 Kresosim methyl, 200 g a.i./ha

Acrinathrin, 70 g a.i./ha

S2

3 S3

4 S4

5 S5

7 Azoxystrobin, 400 g a.i./ha S7

8 S8

9 Kresosim methyl, 400 g a.i./ha

Acrinathrin, 140 g a.i./ha

S9

10 S10

12 S12

14 S14

a

All samples taken on days of treatments were taken prior to treatment.

A. Aguilera et al. / Food Control 25 (2012) 594e600 595

http://www.marm.es/es/agricultura/temas/medios-de-produccion/productos-fitosanitarios/registrohttp://www.marm.es/es/agricultura/temas/medios-de-produccion/productos-fitosanitarios/registrohttp://www.marm.es/es/agricultura/temas/medios-de-produccion/productos-fitosanitarios/registrohttp://www.marm.es/es/agricultura/temas/medios-de-produccion/productos-fitosanitarios/registrohttp://www.marm.es/es/agricultura/temas/medios-de-produccion/productos-fitosanitarios/registrohttp://www.marm.es/es/agricultura/temas/medios-de-produccion/productos-fitosanitarios/registro

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each greenhouse sampleis showed in Fig. 2. Finally, such as it isalso

indicated in Fig.1,just for the greenhouse samples S1, S3, S5, S8, S10

and S12, each zucchini fruit from the fourth subsample was chop-

ped and analyzed separately from each other fruit within the

subsample to carry out the unit to unit variability study. Immedi-

ately after chopping or cooking, all these samples were kept deep-

frozen (- 20 C) until analyzed.

Extraction of azoxystrobin, acrinathrin and kresoxim methyl

residues in zucchini samples was carried out according to a modi-

cation of the ethyl acetate/GC multiresidue extraction method

developed by the Swedish National Food Administration for fruits

and vegetables (Andersson and Palsheden,1998; Valverde, Aguilera,

Rodriguez, Boulaid, & Soussi, 2002). A brief description of the

extraction procedure is as follows: 37.5 g of thoroughly homoge-nized samplewere blended with 100 mL of ethyl acetate and 20 g of

anhydrous sodium sulfate for 5 min, then, the solvent phase wasltered through a 10 g sodium sulfate layer. The ltrate was dried

further by shaking with 5 g sodiumsulfate. 25 mL ethyl acetate layer

was transferred to a 100 mL round-bottomed ask and was

concentratedto approximately 2 mL on rotary vacuum evaporatorat

37C. The concentrate was quantitatively transferred to a graduated

test tube, and the volume was adjusted to 5 mL with ethyl acetate

and then to 10 mL with cyclohexane. The extract was ltered

through a 0.45mm microlter by suction with a 10 mL syringe. The

extracts so obtained, which contained 0.94 g sample/mL, were

analyzed by GC-ECD using the operating conditions described

above.A dilution factorof100/(100 e % waterlost) was takinginto

account to determine pesticide levels in the cooked samples.

During the study, a number of quality control recovery testswere conducted on zucchini samples previously analyzed and

demonstrated not to contain any residues of azoxystrobin, acrina-

thrin and kresoxim methyl. In total, ten recovery tests (sixteen in

the case of azoxystrobin) were performed on blank zucchini

samples at spiking levels ranging from 0.05 to 0.5 mg/kg. Previous

validation studies included the evaluation of the linearity and limits

of quantication of the analytical method. The linearity of the

method (peak area versus concentration of matrix matched stan-

dard solutions) was evaluated in the range of 0.01e0.53 mg/kg for

acrinathrin, 0.05e0.50 mg/kg for azoxystrobin, and 0.01e0.51 mg/

kg for kresoxim methyl. In all cases, good linearities were achieved

over the assessed concentration ranges, with correlation coef-

cients >0.99; and both the relative standard deviation (RSD) of the

mean responses from quadruplicate injections of standard solu-tions and the RSD from 5-point calibration injections were

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3. Results and discussion

3.1. Recovery tests

Individual recovery ranges, mean recovery values, and the cor-

responding relative standard deviations (RSD) obtained for azox-

ystrobin, acrinathrin and kresoxim methyl in the recovery tests

performed along all the study are shown in Table 2. These values

can be considered acceptable according to the validation and

quality control criteria usually applied for pesticide residue analysis

(European Commission, 2009; Fajgelj & Ambrus, 2000).

3.2. Unprocessed zucchini

Azoxystrobin, acrinathrin and kresoxim methyl residue levels

(mean of unprocessed samples A, B and C) determined in the

zucchini samples analyzed along all the study are indicated in

Table 3. Mean residue levels in unprocessed zucchini ranged

between not detected (

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acrinathrin and kresoxim methyl). The mean and standard devia-

tion (SD) values obtained for the processing factors are indicated in

Table 4.

The mean washing factors were 0.3, 0.2 and 0.0 for acrinathrin,

azoxystrobin and kresoxim methyl, respectively. Therefore the

application of a typical household washing treatment to the

zucchini seems to reduce the levels of acrinathrin and azoxystrobin

in the range of 70e80%, whereas kresoxim methyl seems to be

completely eliminated (100% reduction). However, the statistical

evaluation of the results, by means of the paired tstatistical test,

shows that the residue levels found in the washed samples were

statistically different from the residue levels found in the unpro-

cessed samples just for azoxistrobin and kresoxim methyl, but not

for acrinathrin (t3.50 for azoxistrobin, t4.11 for kresoxim

methyl andt2.47 for acrinathrin, with 9 degrees of freedom for

azoxistrobin and 4 degrees of freedom for kresoxim methyl and

acrinathrin, andP0.05). A 75% of azoxystrobin residue reduction

after washing process was found in literature in grapes (Lentza-

Rizos, Avramides, & Kokkinaki, 2006), and reduction percentages

around or over than 50% were found for other pesticide/crop

combination (Cabras et al., 1998; Holland, Hamilton, Ohlin, &

Skidmore, 1994). However, washing factors around 1 (which

means no pesticide reduction by washing) have also been reportedfor different pesticide/crop combinations, such as pyridaben and

tralomethrin in pepperand tomato, or pyrifenox in tomato (Boulaid

et al., 2005; Valverde et al., 2002).

Residues of both acrinathrin and kresoxim methyl were not

detected in any of the peeled zucchini samples (with the excep-

tion of the 0.04 mg/kg of kresoxim methyl determined in the S10

peeled sample), resulting in mean peeling factors of zero for these

two pesticides (100% mean reduction by peeling). On the other

hand, azoxystrobin residues were determined in ve of the

peeled samples at levels ranging between 0.05 and 0.40 mg/kg,

resulting in a mean peeling factor for azoxystrobin of 0.1 (90%

mean reduction by peeling). In all cases, the difference in the

residues found in the peeled samples was statistically different

from the residues found in the unprocessed samples (t 3.61 forazoxistrobin, t3.04 for kresoxim methyl and t3.16 for acri-

nathrin, with 9 degrees of freedom for azoxistrobin and 4 degrees

of freedom for kresoxim methyl and acrinathrin, and P 0.05).

These results could indicate that azoystrobin enter into the

zucchini esh more easily than acrinathrin and kresoxim methyl,

whose residues practically remain in the peel. However, azox-

ystrobin levels in the unprocessed samples were much higher

than the levels of acrinathrin and kresoxim methyl, and the small

amount of azoxystrobin determined in some of the peeled

samples could be in part the result of contamination during the

peeling process, such as it has been already reported for other

pesticides/fruits combinations (Boulaid et al., 2005; Fernndez-

Cruz et al., 2004).

InFig. 4are represented the residue levels of (a) azoxystrobin,(b) acrinathrin and (c) kresoxim methyl in cooked samples versus

the residue values determined in the corresponding unprocessed

samples. The mean cooking factor calculated for azoxystrobin was

1.4, the difference in the residues found in the cooked samplesbeing statistically different from the residues found in the unpro-

cessed samples (t 2.79,with 19 degrees of freedom andP 0.05).

However, these results indicate that the cooking process applied to

the zucchini does not reduce, signicantly, the amount of azox-

ystrobin, since the obtained value ofw1.4 for the cooking factor is

justied by the concentration of the zucchini pure in a factor of

w1.5 as a consequence of a water loss ofw35%. Specically, the

water loss determined in the 22 cooked zucchini samples was

35.47.0%. On the other hand, the mean cooking factors obtained

for acrinathrin and kresoxim methyl were 0.9 and 1.1. In both cases,

the difference in the residues found in the cooked samples was not

statistically different from the residues found in the unprocessed

samples (t0.76 for kresoxim methyl and t 1.49 for acrinathrin,

with 9 degrees of freedom and P

0.05). Taking into account these

Table 4

Mean processing factors and standard deviations (SD) obtained for azoxystrobin,

acrinathrin and kresoxim methyl in zucchini.

Process M ean Processin g Fac tor SD

Azoxystrobi n Acri na thr in K resoxi m methyl

Washinga 0.20.1 0.30.1 0.0 0.0

Peelinga 0.10.1 0.00.0 0.0 0.1

Cookingb 1.40.5 0.90.2 1.1 0.2

a n 10 for azoxystrobin and 5 for acrinathrin and kresoxim methyl.b

n

20 for azoxystrobin, 10 for acrinathrin and kresoxim methyl.

Zucchini - Azoxystrobin

Cooked/ Unprocessed

y = x

y = 1,2084x

R2= 0,867

0,00

0,50

1,00

1,50

2,00

2,50

3,00

0,00 0,50 1,00 1,50 2,00 2,50 3,00

Azoxystrobin levels in unprocessed zucchini (mg/kg)

Azoxystrobinlevelsincooked

zucchini(mg/kg)

Zucchini - Acrinathrin

Cooked/ Unprocessed

y = x

y = 0,7611x

R2= 0,8203

0

0,05

0,1

0,150,2

0,25

0,3

0,35

0,4

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Acrinathrin levels in unprocessed zucchini (mg/kg)

Acrinathrinlevelsincooked

zucchini(mg/kg)

Zucchini - Kresoxim methyl

Cooked/ Unprocessed

y = x

y = 1,0592x

R2= 0,787

0

0,05

0,1

0,15

0,2

0,25

0,3

0 0,05 0,1 0,15 0,2 0,25 0,3

Kresoxim methyl levels in unprocessed zucchini (mg/kg)

Kresoximm

ethyllevelsincooked

zucchini(mg/k

g)

Fig. 4. Residue levels (mg/kg) of azoxystrobin, acrinathrin and kresoxim methyl in

unprocessed samples versus residue levels obtained in cooked samples.

A. Aguilera et al. / Food Control 25 (2012) 594e600598

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values, and the concentration factor of the zucchini pure during

cooking process, we can conclude that the average reductions of

the amounts of kresoxim methyl and acrinathrin during the cook-

ing process were in the range ofw30e40%.

3.4. Residue variability among individual zucchini

The minimum, maximum and mean residue levels of azox-ystrobin, acrinathrin and kresoxim methyl determined in the 10

individual units of zucchini analyzed from the samples S1, S3, S5,

S8, S10 and S12 are reported in Table 5. Residues of the applied

pesticides were found in all of the zucchini units analyzed, except

in some units from the sample S8, in which, acrinathrin residues

were not detected in any of them and kresoxim methyl residues

were not detected in 3 zucchini units (in these cases, a residue

level of zero was used to calculate the variability factors). The

obtained unit to unit variability factors are also included in

Table 5 and ranged from 1.3 to 2.4, with an average of 1.8 for

azoxystrobin (n6), 1.4 for acrinathrin (n4) and 1.8 for kre-

soxim methyl (n5).

The unit to unit variability factors obtained in this work are

much lower than the variability factor recommended by the WorldHealth Organization (WHO) to be used as default value for

consumer risk assessment (acute exposure through diet) of pesti-

cide residues in zucchini (World Health Organization, 1997).

However, our results are consistent with those evaluated by the

European Food Safety Authority (EFSA) from a number of super-

vised trials variability studies on medium size commodities

(25e250 g unit weight), with a minimum of 50 items in each study

(European Food Safety Authority, 2005). Pesticide variability factors

obtained in those studies ranged between 1.2 and 4.9, the average

variability factor for supervised trials being 2.8. Finally, variability

factors obtained in this work are very similar to those obtained by

other authors for different pesticides in oranges (Lentza-Rizos &

Tsioumplekou, 2001), potatoes (Lentza-Rizos & Balokas, 2001),

kaki fruits (Fernndez-Cruz et al., 2004) or tomatoes (Boulaid et al.,2005), which could justify the use of a default value of 3 for risk

assessment, replacing a range of default values for different

commodities, such as it has been recently proposed (European Food

Safety Authority, 2005).

Acknowledgments

This study was supported by the Spanish Ministry of Education

and Culture (project AGL2000-1485). Authors wish to thank Val-

entina Bussonera for her collaboration in this work.

References

Abou-Arab, A. K. (1999). Behavior of pesticides in tomatoes during commercial andhome preparation. Food Chemistry, 65, 509e514.

Andersson, A., & Palsheden, H. (1998). Multi-residue method for analysis of pesti-cides in fruits and vegetables using ethyl acetate extraction, GPC clean-up andGC determination. Livsmedelsverket Rapport, 17, 9e41.

Arrebola, F. J., Martinez Vidal, J. L., Gonzlez-Rodriguez, M. J., Garrido-Frenich, A., &Snchez Morito, N. (2003). Reduction of analysis time in gas chromatography.Application of low-pressure gas chromatography-tandem mass spectrometry tothe determination of pesticide residues in vegetables. Journal of Chromatog-raphy A, 1005, 131e141.

Boulaid, M., Aguilera, A., Camacho, F., Soussi, M., & Valverde, A. (2005). Effect ofhousehold processing and unit-to-unit variability of pyrifenox, pyridaben andtralomethrin residues in tomatoes.Journal of Agricultural and Food Chemistry, 10,4054e4058.

Burchat, C. S., Ripley, B. D., Leishman, P. D., Ritcey, G. M., Kakuda, Y., &Stephenson, G. R. (1998). The distribution of nine pesticides between the juiceand pulp of carrots and tomatoes after home processing. Food Additives andContaminants, 15, 61e71.

Cabras, P., Angioni, A., Garau, V. L., Pirisi, F. M., Brandolini,V., Cabizta, F., et al. (1998).Pesticide residues in prune processing. Journal of Agricultural and Food Chem-istry, 46, 3772e3774.

Chavarri, M. J., Herrera, A., & Ario, A. (2004). Pesticide residues in eld-sprayedand processed frutis and vegetables. Journal of The Science of Food and Agri-culture, 84, 1253e1259.

Coscoll, R. (1993). Residuos de Plaguicidas en Alimentos Vegetales. Madrid, Spain:Ediciones Mundi-Prensa.

Economou, A., Botitsi, H., Antoniou, S., & Tsipi, D. (2009). Determination of multi-class pesticides in wines by solid-phase extraction and liquid chromatography-tandem mass spectrometry. Journal of Chromatography A, 1216, 5856e5867.

Elkins, E. R. (1989). Effect of commercial processing on pesticide residues in selectedfruits and vegetables. Journal e Association of Ofcial Analytical Chemistry, 72,533e535.

European Commission. (2009). Method validation and quality control procedures forpesticide residues analysis in food and feed. Document SANCO/10684/2009.Brussels: European Commission.

European Food Safety Authority. (2005). Opinion of the scientic panel on plant

health, plant protection products and their residues on a request fromcommission related to the appropriate variability factor(s) to be used for acutedietary exposure assessment of pesticide residues in fruits and vegetables. TheEFSA Journal, 177, 1e61.

Fajgelj, A., & Ambrus, A. (2000). Principles and practices of method validation.Cambridge, UK: Royal Society of Chemistry.

Fernndez-Cruz, M. L., Villarroya, M., Llanos, S., Alonso-Prados, J. L., & Garca-Baudn, J. M. (2004). Field-incurred fenitrothion residues in kakis: comparisonof individual fruits, composite samples, and peeled and cooked fruits. Journal of

Agricultural and Food Chemi stry, 52, 860e863.Garau, V. L., Angioni, A., Aguilera del Real, A., Russo, M., & Cabras, P. (2002).

Disappearance of azoxystrobin, pyrimethanil, ciprodinil and udioxonil ontomatoes in a greenhouse. Journal of Agricultural and Food Chemistry, 50,1929e1932.

Holland, P. T., Hamilton, D., Ohlin, B., & Skidmore, M. W. (1994). Effect of storage andprocessing on pesticide residues in plant products. Pure and Applied Chemistry,66, 335e356.

Lentza-Rizos, C., Avramides, E. J., & Kokkinaki, K. (2006). Residues of azoxystrobinfrom grapes to raisins. Journal of Agricultural and Food Chemistry, 54, 138e141.

Lentza-Rizos, C., & Balokas, A. (2001). Residue levels of chlorpropham in individualtubers and composite samples of postharvest-treated potatoes. Journal of

Agricultural and Food Chemistry, 49, 710e714.Lentza-Rizos, C., & Tsioumplekou, M. (2001). Residues of aldicarb in oranges: a unit-

to unit variability study. Food Additives and Contaminants, 18, 886e897.Lin y Vicente, C. (2009). Vademecum de Productos Fitosanitarios y Nutricionales.

Madrid, Spain: Carlos Lin y Vicente.Martinez Galera, M., Gil Garca, M. D., Rodriguez Lallena, J. A., Lopez Lopez, T., &

Martinez Vidal, J. L. (2003). Dissipation of pyrethroid residues in peppers,zucchinis and greenbeans exposed to eld treatments in greenhouse: eval-uation by decline curves. Journal of Agricultural and Food Chemistry, 51,5745e5751.

Rabolle, M., Spliid, N. H., Kristensen, K., & Kudsk, P. (2006). Determination offungicide residues in eld-grown strawberries following different fungicidestrategies against gray mold (Botrytis cinerea). Journal of Agricultural and FoodChemistry, 54, 900e908.

Randhawa, M. A., Anjum, F. M., Ahmad, A., & Randhawa, M. S. (2007). Field incurredchlorpyrifos and 3, 5, 6-tricholoro-2-pyridinol residues in fresh and processed

vegetables.Food Chemistry, 103, 1016e

1023.

Table 5

Residue variability among individual zucchini and minimum, maximum and mean

residue levels, in milligrams per kilogram, obtained in the analysis of 10 individual

units of zucchini from samples S1, S3, S5, S8, S10 and S12.

Pesticide Sample Min/max

values (mg/kg)

Mean

(mg/kg)

Variability

factora

Azoxystrobin S1 0.69/4.81 1.96 2.4

S3 0.39/1.44 0.75 1.9S5 0.20/0.53 0.32 1.7

S8 1.29/5.12 3.48 1.5

S10 0.39/1.52 0.82 1.8

S12 0.21/0.44 0.32 1.4

Acrinathrin S3 0.23/0.42 0.33 1.3

S5 0.04/0.12 0.07 1.7

S8 ndb/ndb

S10 0.07/0.24 0.17 1.4

S12 0.02/0.07 0.05 1.4

Kresoxim-methyl S3 0.06/0.52 0.37 1.4

S5 0.05/0.12 0.08 1.5

S8 ndb/0.04 0.02 2.0

S10 0.09/0.50 0.26 1.9

S12 0.04/0.13 0.08 1.6

a Max value/mean.b

Not detected.

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Sannino, A., Bolzoni, L., & Bandini, M. (2004). Application of liquid chromatographywith electrospray tandem mass spectrometry to the determination of a newgeneration of pesticides in processed fruits and vegetables. Journal of Chroma-tography A, 1036, 161e169.

Soler, C., James, K. J., & Pic, Y. (2007). Capabilities of different liquid chromatographytandem mass spectrometry systems in determining pesticide residues in food.Applicationto estimate theirdaily intake.Journal of Chromatography A, 1157, 73e84.

Suhre, F. B. (2000). Pesticide residues and acute risk assessment-the U.S. EPAapproach.Food Additives and Contaminants, 17, 569e573.

Taylor, M. J., Hunter, K., Hunter, K. B., Lindsay, D., & Le Bouhellec, S. (2002). Multi-

residue method for rapid screening and conrmation of pesticides in crude

extracts of fruits and vegetables using isocratic liquid chromatography withelectrospray tandem mass spectrometry. Journal of Chromatography A, 982,225e236.

Tomlin, C. (2009). The pesticide manual (15th ed.). Surrey, U.K: British CropProtection Council.

Valverde, A., Aguilera, A., Rodrguez, M., Boulaid, M., & Soussi, M. (2002). Pesticideresidue levels in peppers grown in a greenhouse after multiple applications ofpyridaben and tralomethrin. Journal of Agricultural and Food Chemistry, 50,7303e7307.

World Health Organization (WHO). (1997). Food consumption and exposure assess-

ment of chemicals. Geneva, Switzerland: World Health Organization.

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