The effects of ultrasonic irradiation in combination with ozone on the reduction of residual ethion of tangerine (<i>Citrus reticulata</i> Blanco cv. Sai Nam Pung) fruit after harvest

doi:10.4236/as.2013.45B002

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Vol.4, No.5B, 7-11 (2013) Agricultural Sciences

doi:10.4236/as.2013.45B002

The effects of ultrasonic irradiation in combination

with ozone on the reduction of residual ethion of

tangerine (Citrus reticulata Blanco cv. Sai Nam Pung)

fruit after harvest

Kanda Whangchai1,2,3*, Satit Phiyanalinmat4, Jamnong Uthaibutra1,2,3, Sarunya Pengphol5,

Nakao Nomura6

1Postharvest Technology Innovation Center, Commission on Higher Education, Bangkok, Thailand;

*Corresponding Author: [email protected]

2Postharvest Technology Research Institute, Chiang Mai University, Chiang Mai, Thailand

3Postharvest Technology Research Institute, Chiang Mai University, Chiang Mai,Thailand

4Department of Industrial Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand

5Faculty of Agriculture and Industrial Technology,Nakonsawan Rajabhat University, Nakonsawan, Thailand

6Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, lbaraki, Japan

Received 2013

ABSTRACT

Ethion residue removal efficiency using indi-

vidual and combined effects of ultrasonication

(US), ozonation (O3), ultrasonication and ozona-

tion (US/O3) was investigated. A 1 mg·L-1 stan-

dard ethion was subjected to an ultrasonic irra-

diation (3W input power) device with different

frequencies of 108, 400, 700, 1000 kHz, and to an

ozone with a concentr ation of 200 mg · mL-1 wi th

various exposure times (0, 15, 30, 45 and 60

minutes). Reduction of residual ethion was de-

termined by gas chromatography with flame

photometric detection (GC-FPD). It was found

that 1000 kHz ultrasonic irradiation for 60 min-

utes was the most effective treatment for re-

ducing ethion concentration. Additionally, ozone

could reduce the concentration of standard

ethion after 60 minutes of exposure. Ultrasonic

irradiation in combination with ozone had a

synergistic effect in reducing standard ethion

concentration, with the highest rate occurring

within the first 15 minutes. Ethion concentration

was reduced to 75.43% after ultrasonic irradia-

tion at 1000 kHz and ozone exposure for 60 min-

utes. The effectiveness of the combined scheme

for reducing of ethion re sidues on tangerine was

also determined by GC-FPD. The ethion residue

on fresh tangerines after ultrasonic irradiation

and ozone washing was reduced by 73.03% after

60 minutes. The present study demonstrates

that ultrasonic irradiation and ozone exposure

could be use d to re du ce e thi on resi du es in tre ate d

tangerine in order to meet the Standards for

Pesticide Residue Limit s.

Keywords: Tangerine; Ethion; Pesticide Residue;

Ozone; Ultrasonic Irradi ation

1. INTRODUCTION

The economical important pests in tangerine produc-

tion are Asian citrus psyllid (Diaphorina citri Kuwayama:

Psyllidae) the carrier of citrus greening disease (green-

ing), citrus aphid (Toxoptera sp.), chilli thrips (Scirto-

thrips dorsalis Hood: Thripidae), and the African red

mite (Eutetranychus africanus Tucker: Tetranychidae).

The pest feed on tangerine fruits and spread diseases

which in turn ruin the fruits’ appearance. To prevent

these growers, they have to apply a lot of chemical pesti-

cides every week, even at the harvesting time to improve

the tangerines’ aesthetic quality.

There were several batches of tangerine in one plant at

a time reported by Davis and Albrigo (1994) ]1[. There-

fore, in one batch, the chemical pesticides applied to the

tangerines, it would unavoidably affect other batches,

and led to the chemical residue problems. The insecti-

cides used for controlling thrips were ethion, abamectin,

imidacloprid, methomyl, and carbosulfan, respectively.

Ethion is an organophosphate pesticide for controlling

aphids, mites, and thrips. It inhibits the cholinesterase

enzyme in an insect’s nervous system. Currently, grow-

ers widely use ethion, which leaves the chemical residues

on the surface of fruits and vegetables, and sometimes

K. Whangchai et al. / Agricultural Sciences 4 (2013) 7-11

absorbs into the plant tissues. It has been reported that

tangerines consisted of ethion concentrations above the

Maximum Residue Limits (MRL) level (1.0 mg·kg-1),

and 31.8% of the sampled fruits were contaminated with

ethion, cypermethrin, profenophos, carbaryl, chlopyrifos,

and carbosulfan residue below the tangerine MRL level.

They analyzed the peel and flesh of 50 tangerine fruits

collected from the growers, local market and super mar-

ket in Chiang Mai, Lamphun, and Lampang from No-

vember 2008 to December 2009. They found that pesti-

cide residue content, i.e. ethion, profenofos, and triazofos

were higher than the MRL level. An average ethion con-

centration of 1.14 mg·kg-1, it was found in 92% of the

peel samples. Moreover, 50% of tangerine flesh samples

were found to contain an average concentration of 0.01

mg·kg-1 ethion [2].

Ultrasonic irradiation technology effectively reduces a

variety of organic and inorganic contaminants and its

acoustic cavitations generate many hot spots with high

temperatures and pressures those cause the sonolysis of

H2O molecules. Consequently, radical species H, ●OH,

●OOH are formed which lead to a direct destruction of

chemicals in aqueous solution [3]. Hoffman et al.(1996)

reported that ultrasonication at the frequency of 20 to

500 kHz was the effective method in the rapid destruc-

tion of organic contaminants in water [4]. In addition,

Wang et al. (2000) indicated that methyl parathion could

be degraded using ultrasonication at a frequency of 40

kHz [5]. While Song et al. (2007) reported that ultra-

sonication at 200 kHz for 240 seconds effectively to sink

Microcystis surface scum and could be used to reduce

mycrocystin toxin and musty odor substances in aquaculture

pounds [6]. There was no report on the treatment with

ultrasonication and ozonation especially on tangerine.

Ozonation is a promising method to reduce chlopyrifos

in the pericarp and aril of fresh lychee [7]. Furthermore,

Inan et al.(2007) reported the reduction of aflatoxin B1

content in flaked and chopped red peppers (Capsicum

annuum) by 80 and 93% at the rate of 33 and 66 mg·L-1,

respectively after 6 hours of ozone exposure [8]. Wu et

al. (2007) demonstrated that using dissolved ozone (1.4

mg· L -1) for 60 minutes was the effective method to re-

duce 60% - 99% of methyl-parathion, cypermethrin,

parathion and diazinon in aqueous solution [9]. This re-

search mainly studied the effectiveness of ultrasonic ir-

radiation and ozone on the reduction of standard ethion

and residual ethion on tangerine.

2. MATERIAL AND METHODS

Ethion standard was purchased from Sigma-Aldrich

Laborchemikalien GmbH (Stienheim, Germany) with a

99.9% purity (ethion structure is shown in Figure 1).

Ethion stock solution (1000 mg·L-1) was prepared for the

pesticide residue analysis using acetone as the solvent for

high-performance liquid chromatography (HPLC) grade

99.9%, from RCI Labscan Ltd. (Bangkok, Thailand).

The solution was diluted with deionized distilled water to

the appropriate concentrations.

Ultrasonic devices, with an input power of 3 watts and

4 varying frequencies; 108, 400, 700, 1000 kHz and

made by Honda Electronics Company (Toyohashi, Aichi,

Japan), were utilized for three replications. A polyethyl-

ene cylinder reactor 10 cm in diameter, equipped with a

transducer at the lower part was used. Standard ethion

(25 mL) or KI solution in a flask was sonicated in an

ultrasonic reactor.

Ozone gas produced by an ozone generator (Ozonizer,

Sky zone model S05AE) was bubbled into ethion solu-

tion in a flask. The ozone gas was bubbled with a flow

rate of 25 ml·min-1. Dissolved ozone was determined by

the indigo colorimetric method [11].

The treatments that shown good results in ethion deg-

radation from above experiment was used for combina-

tion of ultrasonication and ozone treatment. The ethion

standard was prepared in the ultrasonic reactor mention

ealier. The solution was bubbled with ozone gas from

ozone generator. Samples were collected for the deter-

mination of ethion concentration using GC-FPD (Agilent

Technologies Model 6890) and percentage of removal

rate of the ethion were calculated as the degradation per-

centage.

2.1. Study of Optimum Frequency of

Ultrasonic Irradiation and Ozone

Treatment for Liberation of Iodine and

Reducing Standard Ethion Solution at

Different Times

Standard ethion concentration of 1 mg·L-1 or 2% KI

solution was prepared in a flask and then placed inside

the ultrasonic reactor mentioned earlier and subjected to

different frequencies at 108, 400, 700, and 1000 kHz. A

200 mg·L-1 ozone gas was bubbled for 15, 30, 45 and 60

minutes through the ethion solution or KI. The concen-

tration of iodine liberation from 2% potassium iodine

with different times, was measured at 354 nm using

spectrophotometer. Finally, three replicates of ethion

samples were analyzed by a gas chromatograph equipped

with a flame photometric detector (GC-FPD). Then, the

Figure 1. The chemical structure of ethion [10].

K. Whangchai et al. / Agricultural Sciences 4 (2013) 7-11 9

percent removal of the ethion was calculated at each col-

lection time to compare the best method.

2.2. Reduction of Ethion on Harvested

Tangerine using Ultrasonic Irradiation

and Ozone

An ultrasonic device volume 55 L equipped with eight

transducers and ultrasonic frequency at 1000 kHz 24 W

was used in large-scale application. The ultrasonic device

was also made by Honda Electronics Company (Toyo-

hashi, Aichi, Japan). Tangerine samples were treated with

ethion 1 day before harvesting. The fruits were immersed

in distilled water and subjected to washing using ultra-

sonic reactor, ozone and their combination while wash-

ing using only distilled water was employed as the con-

trol. The 5 g of chopped tangerine was extracted with

acetone and methylene chloride homogenized at 13,000

rpm for 1 minute and dried using rotary vacuum evapo-

ration at 340 mbar [12]. The final solvent was HPLC

grade of acetone. Then the samples were analyzed ethion

residue using GC-FPD as previous report [13].

2.3. GC-FPD Instrument and Conditions

The GC-FPD analysis was performed with an Agilent

Technologies (Wilmington, DE) model 6890 gas chro-

matograph equipped with a flame photometric detector.

The GC was carried out using a fused silica capillary

column HP-5, 5% Phenyl Methyl Siloxane, with dimen-

sions of 30 m × 0.32 mm i.d. and a 0.25 μm film thick-

ness (Agilent Technologies). The temperature was pro-

grammed at 10℃·min-1 from the initial temperature at

100℃ to 200℃. And then at 4℃·min-1, it increased to

the final temperature of 220℃. A purified He carrier gas

was used with the flow rate of 3.6 mL·min-1. The detec-

tor temperature was set at 250℃. Those sample solutions

(1.0 µL) were injected in splitless mode, and the quanti-

fication of ethion was performed using ethion standard as

a reference .

2.4. Statistical Analysis

All experiments were replicated three times and evalu-

ated with a regression procedure using the SPSS version

17. Duncan’s Multiple Range Test (*P ≤ 0.05) was per-

formed to determine the significant difference among

various treatments.

3. RESULTS AND DISCUSSION

3.1. Study of Optimum Frequency and Time

for Iodine Liberation and Reducing

Standard Ethion Solution by Ultrasonic

Irradiation and Ozone Treatment

Iodine production was a direct measurement of soni-

cation and ozonation effects. Iodine yield increased with

increasing ultrasonic frequencies directly and it reached

the highest value of iodine production rate (absorbance

of OD 354) when ultrasonic frequency was 1000 kHz

with ozone exposure for 60 minutes (Figure 2) These

results indicated that ultrasonic irradiation generated

highly active hydroxyl radicals, which reacted with po-

tassium iodide to release iodine in the process [14].

The effectiveness of ultrasonic irradiation to reduce

the concentration of standard ethion solution (1 mg·L-1)

was also investigated. It was found that the ethion con-

centration was significantly reduced with prolonged ul-

trasonic exposure time. Moreover, ultrasonic irradiation

at 1000 kHz for 60 minutes was the most effective treat-

ment for reducing ethion concentration (Figure 3). The

advantage effect of high ultrasonic frequency may be due

to the increasing cavitational activity which led to a

higher number of collapsing cavities directly influencing

Exposure time(m in)

0 102030405060

O D 354 nm of 2% KI

Control

108kHz

400kHz

700kHz

100kHz

100kHz+O3

400kHz+O3

700kHz+O3

1000kHz+O3

Figure 2. Changes of KI absorbance at 354 nm after exposed to

ultrasonic irradiation and ozone treatment.

Exposure time(min)

0 102030405060

% degradation of ethion

100

control

108Hz

400Hz

700Hz

1000Hz

Figure 3. Percent removal of ethion standard solution using

ultrasonic irradiation with various frequencies.

K. Whangchai et al. / Agricultural Sciences 4 (2013) 7-11

relevant report of Yao et al.(2010) that the optimal fre the

reduction rate of ethion. This evidence followed the

quency for parathion degradation occurred at 600 kHz

and it attributed to the much higher ●OH yield compared

to treatments at 200 kHz[15].

Similar results obtained for the ozone-treated standard

solution of ethion. Reduction of ethion concentration was

directly proportional to increase in ozone exposure time.

At 60 minutes exposure, ethion concentration decreased

by 66.85% (Figure 4). Ozone is a strong oxidant and it

could possibly degrade the ethion. As reported by Ku et

al. (1998) the diazinon degradation occurred within 1

hour of ozone treatment [16]. These results agreed well

with the previous studies on the reduction of carbamate

pesticides and some organic phosphorus in water solu-

tion after ozone treatment with the same range of contact

times [17].

The ethion solution treated with ultrasonication in

combination with ozone (US/O3) showed the improved

rate of ethion degradation, with the highest degradation

rate took place after the first 15 minutes. This may be

due to the synergistic effect of ultrasonic-ozone treatment,

degraded and oxidized ethion structure. Moreover, the

combination (US/O3) scheme for 60 minutes with 1000

kHz US, its exposure time reduced the ethion concentra-

tion by 75.43%, which is significantly (*P < 0.05) higher

compared with other treatments (Figure 4). Therefore,

ultrasonication and ozonation in combination exhibited a

promising treatment for residual ethion removal that ac-

complished by ozone or ultrasonication alone. Thus,

there was a synergistic effect to use ultrasonic and ozone

treatments together. This followed the similar findings by

Weaver et al. (1998) who reported the importance of the

rapid degradation of organic contaminants using ozone

and ultrasonic irradiation (20 kHz) resulting in an in-

crease of hydroxyl radicals[3].

Exposure time( min)

0 102030405060

% degradation of ethion

100

Control

108kHz+O3

400kHz+O3

700kHz+O3

1000kHz+O3

Figure 4. Percent removal of ethion standard solution using the

combinations of ultrasonic irradiation and ozone treatment.

3.2. Reduction of Ethion on Harvested

Tangerine Using Ultrasonic Irradiation

and Ozone

Tangerine fruits were immersed in an ultrasonic reac-

tor with the frequency of 1000 kHz and combined with

ozone treatment in order to reduce residual ethion. It was

found that the ethion residue on fresh tangerine showed

the lowest level (0.03 ppm) or 73.07% of removal rate

when the ultrasonic frequency was 1000 kHz and com-

bined with the ozone treatment for 60 minutes with sig-

nificant (*P < 0.05) different when compared with an

individual treatment and the control, which was im-

mersed in distilled water (Figure 5). This tendency could

be explained by the reaction of ultrasonic frequencies

with exposure ozone producing the ●OH radical, which

effectively decomposed ethion residue on the tangerine

surface. Similarly, Wenrong et al. (2002) reported that

the decomposition rate of arsenazo treated by ozone or

ultrasonic was more rapid than that treated by ozone

alone and the structure of arsenazo was decomposed

more completely[18]. In addition, Wu et al.(2007) also

indicated that ozone water treatment could effectively

reduce pesticides (methyl-parathion, parathion, diazinon

and cypermethrin) residue on Pak Choi (Brassica rapa)

surface [9].

4. CONCLUSIONS

The concentration of ethion was reduced after using

ultrasonic or ozone treatment. The reduction could in-

crease with increasing contact time directly. The higher

the ultrasonic frequencies, the greater the percent re-

moval could achieve. The combined ultrasonic and ozone

treatments had a synergistic effect on ethion degradation

controlO3US US+O3

Ethion concentration(ppm)

0.0

1.0

0.8

0.6

0.4

0.2

Treatment

Figure 5. Ethion residue in tangerine after washing in the com-

bination of ultrasonication and ozonation. Error bars denote

standard deviations. Different letters indicate significant dif-

ferences by Duncan’s multiple range test (p ≤ 0.05).

K. Whangchai et al. / Agricultural Sciences 4 (2013) 7-11

in both aqueous solution and ethion treated tangerines.

Therefore, further studies to reduce the toxicity of pesti-

cides contaminated agricultural products are also re-

quired.

Openly accessible at

5. ACKNOWLEDGEMENTS

This research was supported by the Postharvest Technology Innova-

tion Center, Commission on Higher Education, Bangkok. The authors

are also grateful to the Faculty of Science and Postharvest Technology

Research Institute, Chiang Mai University, Thailand for providing the

laboratory facilities and to Honda Electronics Company Toyohashi,

Aichi, Japan for ultrasonic device support.

REFERENCES

[1] Davis, F. S. and Albrigo, L. G. (1994) Citrus. CAB

Interntioal, Walling, Oxon, U.K., p.254.

[2] Wongkaew, L. (2009) Survey of the use of pesticides in

tangerine in Chiang Mai province Thailand. Annual

report of Department of Agriculture.

http://it.doa.go.th/pibai/pibai/n13/v-6-july/jakfarm.html

[3] Weavers, L.K., Ling, F.H. and Hoffmann, M.R. (1998)

Aromatic compound degradation in water using a combi-

nation of sonolysis and ozonolysis. Environmental Sci-

ence & Technolology,32, 2727-2733.

doi:10.1021/es970675a

[4] Hoffmann, M.R, Hua, I. and HÖchemer, R. (1996)

Application of ultrasonic irradiation for the degradation of

chemical contaminants in water. Ultra sonics Sonochemistry,

3, S163-S172.

doi:10.1016/s1350-4177(96)00022-3

[5] Wang, J., Pan, Z., Zhang, Z., Zhang, X., Wen, F., Ma, T.,

Jiang, Y., Wang, L., Xu, L. and Kang, P. ( 2006) Sono-

catalytic degradation of methyl parathion in the

cvpresence of nanometer and ordinary anatase titanium

dioxide catalysts and comparison of their sonocatalytic

abilities. Ultrasonics Sonochemistry, 13, 493-500.

doi:10.1016/j.ultsonch.2005.11.002

[6] Song, W. and O’Shea, K.E. (2007) Ultrasonically induced

degradation of 2-methylisoborneol and geosmin. Water

Research, 41, 2672-2678.

[7] Whangchai, K., Uthaibutra, J., Phiyanalinmat , S., Peng-

phol, S. and Nomura,N. (2011) Effect of ozone treatment

on the reduction of chlorpyrifos residues in fresh lychee

fruits. Ozone Science and Engineering, 33, 232-236.

doi:10.1080/01919512.2011.554313

[8] Inan, F., Pala, M. and Doymaz, I.( 2007) Use of ozone in

detoxification of aflatoxin B1 in red pepper. Journal of

Stored Product Research, 43, 425-429.

doi:10.1016/j.jspr.2006.11.004

[9] Wu, J., Luan, T., Lan, C., Lo, T. W.H. and Chan, G. Y. S.

(2007) Removal of residual pesticides on vegetable using

ozonated water. Food Control, 18, 466-472.

doi:10.1016/j.foodcont.2005.12.011

[10] Ethion.[Online].Available: http://toxipedia.org/display/toxi

pedia/Ethion (January 19, 2011).

[11] Eaton, A.D., Clesceri, L.S., Rice, E.W., Greenberg, A. E.

(2005) Standard Methods for the Examination of Water

and Waste-Water 21th ed. Am. J. Public Health. Washing-

ton DC, USA.

[12] Fenoll, J., P., Hellín, C.M., Martínez, Miguel, M. and

Flores, P. (2007) Multiresidue method for analysis of

pesticides in pepper and tomato by gas chromatography

with nitrogen– phosphorus detection. Food Chemistry,

105, 711-719. doi:10.1016/j.foodchem.2006.12.060

[13] Pengpol,S.,Uthaibutra,J., Arquero, O. A., Nomura,N.

(2011) Reduction of residual Chlorpyrifos on harvested

bird chillies (Capsicum frutescens) using ultrasonication

and ozonation. Thai Journal of Agri cultural Science, 44,

182-187.

[14] Hart, E.J. and Henglein, A. (1985) Free radical and free

atom reactions in the sonolysis of aqueous iodide and

formate solutions. Journal of Physic Chemistry, 89, 4342-

4347. doi:10.1021/j100266a038

[15] Yao, J-J., Gao, N-Y., Li, C. and Xu, B. (2010) Mechanism

and kinetics of parathion degradation under ultrasonic ir-

radiation. Journal of Hazardous Materials, 175, 138-145.

doi:10.1016/j.jhazmat.2009.09.140

[16] Ku, Y., Chang, J.L., Shen, Y.S. and Lin, S.Y. (1998) De-

composition of diazinon in aqueous solution by ozonation.

Water Research, 32, 1957-1963.

doi:10.1016/s0043-1354(97)00353-9

[17] Faust, S.D. and Gomma, H.M. (1972) Chemical hydroly-

sis of some organic phosphorus and carbamate pesticides

in aquatic environment. Environmental Letters, 3, 171-

201. doi:10.1080/00139307209435465

[18] Wenrong, H. and Haiyan, P. (2002) Decomposed charac-

teristic of azo dyes by ozonization with ultrasonic en-

hancement. E-Journal of Chinese Science Bulletin, 47,

986-989.