14 KKU Res. J. 2012; 17(1)

Optimization of Headspace Solid-Phase Microextraction Technique for the Determination of Trace Organochlorine Pesticides in Surface SedimentsAmornrat Wongklom* and Janpen Intaraprasert

Department of Chemistry, Faculty of Science, Ubon Ratchathani University *Correspondent author: amornrat_dekarnkon@hotmail.com

Received November 14,2011

Accepted january 26,2012

Abstract

Headspacesolid-phasemicroextraction(HS-SPME)withgaschromatography–electroncapturedetection

(GC-ECD) for the determination of trace organochlorine pesticides(OPCs) in sedimentwas developed.The

optimumconditionofGC-ECDwasasfollows.TheinjectorandECDtemperatureswere270oCand280oC,

respectively.A15-mDB-1capillarycolumnwasheldat100oCfor2min,increasedto180oCatarateof10oC/min,heldfor4min,andfinallyrampedto280oCatarateof10oC/min,heldfor6min.Thenitrogengas

wasusedasacarriergasandmakingupgasataflowrateof1.5mL/minand28mL/min,respectively.The

HS-SPMEtechniquewasusedforextractionoftheOCPsfromsedimentssamples.Thesuspensionof0.5-gdried

sedimentin1-mLofwaterwasextractedusing100-µmPDMSfiberwithextractiontemperatureof70oCfor60

minwithstirring.Theadditionofotherhydrophilicsolventsandsalthaddifferenteffectsontheextractionof

OCPs.HigherresponsesofOCPswereobtainedwhenwaterwasaddedtothesediment.Thelinearregression

wasgreaterthan0.995(0.004-0.4ng/g,dryweightofsediment).Therelativestandarddeviationwasfoundto

belowerthan10%(n=5).Limitofdetectionwaslowerthan0.01ng/g,dryweight.Themeanrecoverieswere

between80and99%(2levelofconcentration;0.01ng/gand0.1ng/g).TheoptimizedHS-SPMEprocedurehas

beenshowntobereliableforfast,accurateandprecisemonitoringofOCPsinextractedsedimentsamples.This

methodhasbeenexpandedforapplicationtoawiderangeofsedimentandsoilmatrices.

Keywords: headspacesolid-phasemicroextraction,organochlorinepesticides,sediment

1. Introduction

The contamination of persistent organic

pollutants (POPs) in theenvironmentshasbecomea

globalconcernduetotheircarcinogenicandmultagenic

properties.Organochlorinepesticides(OCPs)havebeen

extensivelyusedinpastdecadesagainstvegetalpests

andvectorbornedeseases,andhavehighlycontaminated

the soil and sediment environments. SeveralOCPs

includingHCHs,aldirn/dieldrin,endosulfanandDDTs

havebeenpromulgatedasPOPsorendocrinedisrupting

KKU Res. J. 2012; 17(1):14-24http : //resjournal.kku.ac.th

15KKU Res. J. 2012; 17(1)

chemicals(1).Althoughtheyhavebeenprohibitedin

developedcountriessince1970sduetotheirtoxicity

andtendencytoaccumulateinlivingorganisms,they

havebeenrecentlydetectedinsoils(2).Organochlorines

characteristicallyhaveverylowsolubilitiesinwater,fat

soluble,andresistanttometabolism.Thecombination

of their persistence in the environment, toxicity and

abilitytobioaccumulatehascausedthemtobelabiled

asenvironmentalhazards(3).

Theprimarystepinsoilandsedimentanalysis

involvestheseparationofOCPsfromthematrix.Several

methodshavebeendevelopedtoaccomplishthisoften

difficulttask,includingsoxhletextraction(4),ultrasonic

solventextraction(5,6),acceleratesolventextraction

(7,8)andmicrowaveextraction(9).Themostpopular

technique usually comprised of extraction, clean-up

and analysis,which require a long time, quantities

ofexpensive,toxicsolventthatcanbeharmfultothe

environment(3).Theprocedureitselfistime-consuming,

tedius,andrequirespre-concentrationoftheanalytes

and remove them from interference components in

thematrix prior to chromatographic analysis (10).

Incomparisonwithheadspace(HS)-SPME, thefiber

isexposedinthevaporphaseabovealiquidorsolid

sample.Indirectimmersion(DI)-SPME,thefiberis

directly immersed in liquid samples.HS-SPMEcan

shortenthetimeofextractionsignificantlybecauseof

thefasterdiffusionrateoftheanalytesingaseousphase

thanintheaqueoussolution.HS-SPMEisespecially

suitablewhenusedintheanalysisofvolatileandsemi-

volatileorganiccompoundbecausethesecompounds

caneasilydiffuseintothesampleheadspacefromother

samplematrices.

InthisstudyeightOCPs,heptachlor,aldrin,

endosulfanI,DDE,endrin,endosulfanII,2,4-DDTand

4,4-DDTwereselectedasimportantinsecticidesthat

havebeenconcernedandprohibitedduetotheirpersistent

nature and chronic adverse effect onwildlife and

humans.Theaimofthisworkwastodevelopanefficient

multi-residuemethodonthebasisofHS-SPMEandgas

chromatographywithelectroncapturedetection(ECD).

For pre-concentration and chromatographic analysis

of theselectedpesticides.Todemonstrate theability

of thismethod to extract the selected semi-volatile

organochlorinepesticidesinsurfacesediment.

2. Materials and Methods

2.1 Reagents and standards

Thetestedpesticides;heptachlor,aldrin,

endosulfanI,DDE,endrin,endosulfanII,2,4-DDTand

4,4-DDTwerepurchasedfromAccuStandard,Inc.,New

Haven,USA.Stockstandardsolutionof2,000µg/mL

ofeachcompoundwaspreparedinhexane.Working

standardsolutionswerepreparedbydilutingthestock

solutionwithhexane.Thestockandworkingstandard

solutionswere stored at 4oC.The sediment samples

werepreparedbyspikingwithanappropriateamountof

theworkingstandard(tobefinalconcentrationof0.04

ng/g).Organicsolventincludinghexane,methanoland

acetonitrilewerepurchasedfromLabScanAsia.Sodium

chloridewasfromCarloErba(Milan,Italy).

2.2 SPME fibers

SPMEholder and fiber assemblies for

manualsamplingwereprovidedfromSupelco(Belle-

fonte, PA,USA). The fiber coatings assayedwere

100-and7-µmpoly(dimethylsiloxane)(PDMS)fiber,

75-µmcarboxen (CAR)-PDMS, 85-µmpolyacrylate

(PA) and 65-µmPDMS-divinylbenzene (DVB).All

fiberswereconditionedinthehotinjectorpartofthegas

chromatograph,accordingtoinstructionsprovidedby

themanufacture.Thenthefiberswasrepeatedlyinjected

intotheGCinjectoruntilinterferingpeakdisappeared.

During thisfiber desorptionprocess theGCcolumn

temperaturewasmaintainedat250oC.

16 KKU Res. J. 2012; 17(1)

2.3 Headspace solid-phase microextraction

(HS-SPME) procedure

Approximately 0.5-g of dried sediment

samplewasplacedin15-mLambervialcappedwith

PTFE-coatedsepta.Sedimentsampleswereprepared

byspikingappropriateamountof theOCPsstandard

solution(2ng/mL)tosedimentstogetthefinalconcen-

trationof0.04ng/g–dryweight.Thesampleswereleft

toevaporatethesolventandadded1-mLofdeionized

water into theambervial.Magneticstirringwith a

8-mmlong tefloncoatedstirbarwasused toagitate

theslurry.Samplevialswereequilibratedbywaterbath

at70oCfor5-min.AfterthattheneedleoftheSPME

devicepierced theseptumof thevialand theSPME

fiberwasexposedat70oCfor60-mintotheheadspace

of the vial and stirred by a small PTFE-coated bar.

Finallythefiberwasretractedintotheneedle,pulled

outfromthevialandinsertedintothehotinjectorport

oftheGCsystemsat270oCfor5-min.Reinsertingthe

SPMEfiberaftertherunwasperformedtoensurethat

therewasnocontaminantsonthefiber.

2.4 Instrumental analysis

Chromatographicanalysiswascarriedout

usingaVarian3600CXgaschromatographequipped

withelectroncapturedetection(ECD).ADB-1capillary

columnforOCPsanalysis(F&WScientific,Folsom,

CA)of15mx0.25mmI.D.coatedwith0.25µmfilm

thicknesswas used.Theoven temperaturewas held

at100oCfor2min,increasedto180oCatarateof10oC/min,heldfor4min,andfinallyrampedto280oC

atarateof10oC/min,heldfor6min.TheGCinjector

was operated in a splitlessmode. Injector andECD

temperatureweresetatthehighesttemperatureallowable

foreachSPMEfiberand280oC,respectively.Nitrogen

wasusedasthecarriergasat1.5mL/minandusedas

make-upgasat28mL/min.

3. Results and Discussion

An effectiveHS-SPMEprocedure for the

determination ofOCPs concentrations in sediments,

SPMEfiber type, extraction temperature and time,

amountofsediment,solventtype,liquidvolumeandthe

additionofhydrophilicsolventandsaltwereoptimized.

3.1 Selection of SPME fiber coating

Five commercially available SPME

fibers(100-,7-µmpoly(dimethylsiloxane)(PDMS)fiber,

75-µmcarboxen (CAR)-PDMS, 85-µmpolyacrylate

(PA),65-µmPDMS-divinylbenzene(DVB)fiberwere

compared for efficiently determining theOCPs.The

extractiontemperatureandtimewere70oCand30min,

respectively.Fig2illustratestheeffectoftypeofSPME

fibersontheextractionOCPs.TheOCPswithdifferent

chemical characteristics showeddifferent extraction

behaviors (11). Almost SPMEfiber can extract all

OCPsexceptCAR-PDMS.Alowadsorptionefficiency

oftheCAR-PDMSfiberwasobservedfortheextraction

of2,4-DDTand4,4-DDT(11,12,13).Applicationofthe

75-µmcarboxen(CAR)-PDMSfibershowedadecrease

insignalresponseof2,4-DDTand4,4-DDTbecauseit

hasamorepolarcoatingandalsohasalowaffinityto

theOCPs.WhenPDMSfiberwereused,allOCPscould

beeffectivelyextractedwiththeequilibrationtimeof

30min.Theextractionefficienciesdecreasedwiththe

Journal of Chromatography A. 2001;918: 371-380. 1 (6) Vagi MC, Petsas AS, Kostopoulou MN, Karananoli MK, Lekkas TD. Determination of 2 organolchlorine pesticides in marine sediments samples using ultrasonic solvent extraction followed 3 by GC/ECD. Desalination. 2007;210: 146-156. 4 (7) Yehouenou E, Pazou A, Boko M, Cornelis AMG, Ahissou H, Laleye P, et al. Organochlorine and 5 organophosphorus pesticide residues in the Oueme River catchment in the Republic of Benin. 6 Environment International. 2006;32: 616-623. 7 (8) Keithmaleestti S, Varanusupakul P, Siriwong W, Thirakhupt K, Robson M, Kitana N. Contamination 8 of Organchlorine Pesticides in Nest soil, Egg, and Blood of the Snail-eating Turtle (Malayemys 9 macrocephala) from the chao Phraya River Basin, Thailand. World Academy of Science, Engineering 10 and Technology. 2009;52: 444-449. Thai. 11 (9) Lambropoulou DA, Alanis TA. Optimization of headspace solid phase microextraction conditions 12 for the determination of organophosphorus insecticides in natural waters. Journal of Chromatography 13 A. 2001;922: 243-255. 14 (10) Wurl O, Obbard JP. Organochlorine pesticides,polychlorinated biphenyls and polybrominated 15 diphenyl ethers in Singapore’s coastal marine sediments. Chemosphere. 2005;58: 925-933. 16 (11) Doong R, Liao PL. Determination of organochlorine pesticides and their metabolites in soil samples 17 Using headspace solid-phase microextraction. Journal of Chromatography A. 2001;918: 177-188. 18 (12) Wongklom A, Intaraprasert J. Determination of organochlorine pesticides residues in sediment from 19 Shi river and Moon river by gas chromatography. Journal of Srinakharinwirot University. 2011; 3 20 suppl 1: 20-26. Thai. 21 (13) Wongklom A, Intaraprasert J. Contamination of organochlorine pesticides in sediment from Shi and 22 Moon river, Thailand. Loas Journal on Applied Science. 2011;2(1): 822-827. 23 (14) Santos FJ, Sarrion MN, Galceran MT. Analysis of chlorobenzenes in soils by headspace solid phase 24 microextraction and gas chromatography-ion trap mass spectrometry. Journal of Chromatography A. 25 1997;771: 181-189. 26 (15) Llompart M, Li K, Fingas M. Headspace solid phase microextraction (HS-SPME) for the 27 determination of volatile pollutants in soils. Talanta. 1999;48: 451-459. 28 29 30 31

32 Figure 1. Headspacesolid-phasemicroextractionof

OCPsfromsediment

17KKU Res. J. 2012; 17(1)

decreasingcoatingthickness(7-µmPDMSfiber)and

100-µmPDMSfiberextractedthehighestamountsof

OCPsand theirmetabolites.TheOCPsare typically

consideredashydrophobicorganiccompounds.Thelog

values of octanol-water partition coefficients (KOM)

rangefrom3.7to7.4andthewatersolubilitieswere

from5µg/L(4,4-DDT)to7.3µg/L(gamma-BHC)(11).

Therefore,theseanalyteswouldbeexpectedtopartition

readilyintoamorenon-polarfibercoatingratherthana

polarfibersuchPA,CAR-PDMS,PDMS-DVB.Dueto

thehighcapacityofthePDMS-DVBcoatingtoextract

volatilecompound,someadditionalpeakappearedon

thechromatogramofOCPswhenappliedtosediment

extraction.The100-µmPDMSfiberwasselectedfor

thefurtherexperimentsbasedonthecriteriaoftheOCPs

amountextractedontothefiberandthereproducibility.

SPME fibers (Kspme

) between stationary phase and

analytes,subsequentlyshiftingthesorptionequilibria.

Moreover, elevated temperatures can decrease the

partition coefficient ofOCPs in soil particles (11).

Extraction temperature should be optimized since

it controlled the diffusion rate of theOCPs into the

fibercoating.Fig3illustratedtheeffectofextraction

temperatureofOCPsadsorbedbya100-µmPDMSfiber

withanextractiontimeof30minattemperatureranging

from40to95oC.Anincreaseinextractionefficiencyof

OCPswasobservedwhentemperatureincreased,the

increaseofextractiontemperaturedecreasetheparti-

tioncoefficientbetweenOCPsand sedimentparticle

andincreasingthedesorptionratesofOCPsfromthe

surfaceofsedimentparticletosolution.Theelevated

temperatureincreasethediffusionoftheOCPsfromthe

3.2 Effect of extraction temperature

Sample temperature has an influence

ontheextractionefficiency.Highertemperaturescan

decrease the diffuse coefficient of analytes inwater

andshortentheextractiontime(9,11).Also,elevated

temperatures decrease the distribution coefficient of

solutiontogaseousphase.However,adecreaseinsensi-

tivitywasobservedforheptachlorandaldrinwhenthe

extractiontemperatureexceed70oC.Thesecompounds

haverelativelyhighvaporpressures;3x10-4–6.3x10-6

mmHg,1mmHg=133.3Pa(11).Sincetheadsorption

ofthetargetanalytesbytheSPMEfiberisanexother-

Figure 2.EffectoffiveSPMEfiber,extractiontemperature70oC,extractiontime30min,

additionofwater5mL

18 KKU Res. J. 2012; 17(1)

micprocess.TheSPMEdistributioncoefficients(Kspme

)

betweencoatingmaterialsandanalytesalsodecreaseat

theelevatedtemperature(14)andextractiondisfavored

at high temperature. Thus, the optimum extraction

efficiencywasachievedat70oCandselected for the

furtherexperiments.

3.3 Effect of extraction time

Theextractiontimerequiredtoreachthe

equilibriumat70oCbetweenthe100-µmPDMSfiber

andthesedimentsamplewasstudied.Fig4illustrated

theeffectofequilibrationtimeontheextractionofthe

OCPstargetanalytes, intherangeof15to120min.

Thedifferenceinresponsedependedonthevolatilities,

distributioncoefficientsandstructureoftheOCPs(1).

Theshortequilibriumtimeforheptachlor,aldrin(60

min)maybeduetothehighvaporpressureat70oC.

The long equilibrium time for endrin, endosulfan I,

DDE,endrin,endosulfanII,2,4-DDTand4,4-DDT(120

min)areduetothelowwatersolubilitiesandhighKow

valuesofthesecompounds.Thehigherresponsewas

Figure 4.Effectofextractiontime,using100-µmPDMSfiber,extractiontemperature70oC,

additionofwater5mL

Figure 3.Effectofextractiontemperature,using100-µmPDMSfiber,extractiontime30min,

additionofwater5mL

19KKU Res. J. 2012; 17(1)

observedwhenusinglongequilibriumtimeforallOCPs

(120min).However, theextraction timeof120min

istoolongforHS-SPMEprocedurestoextractOCPs

andnosignificantdifferenceinsensitivitybetweenthe

extractiontimeoftheOCPsfor60and120minwere

observed.Also,theresponseofsomeOCPsincluding

heptachlorandaldrindecreasedafter60min.Thus,the

extractiontimeof60minwasselectedtoperformthe

sedimentsampleanalysis.

3.4 Effect of sample weight

The partition of semi-volatile organic

compoundsbetween thesedimentand theheadspace

isgenerallylow,andthetotalsampleamountswould

influencethereleaserateofOCPsfromthesediment

matrix.Thus,amountsofsedimentsampleswerevaried

from0.5to2.0gthatwereaddedintotheambervial

containing5-mLofdeionizedwater.Fig5illustrated

theeffectofsedimentweightontheextractionefficiency

ofOCPsby theHS-SPMEat70oC.The responseof

OCPsincreasedupondecreasingtheamountofsediment

sample,0.5gofsedimentshowedthehighestresponse.

Thehighloadingofsedimenthamperedthereleaseof

OCPsfromsedimenttowater,subsequentlytheresponse

ofOCPsinheadspacedecreased.Becauseoftheturbu-

lencelevelinthesedimentwaslowandtheviscositywas

high,thetimerequiredforequilibrationandextraction

ofOCPsfromsolidtogaseousphasewaslongwhen

highamountofsedimentwasused.Theresultsshowed

thatsmallamountsofsedimentsamplewereneededand

sufficientforHS-SPMEanalysis.Thus,sampleamount

of0.5gwasselectedforthefurtherexperiments.

3.5 Effect of the addition of the different

solvent to the sediment matrix

Theadditionofsolventcanenhancethe

releaseoftargetanalytesfromthematrix.Therefore,

theeffectofsolventwasinvestigated.Theexperiments

weredoneat70oCafteraddition5mLofwaterand

different type of solvents such as methanol,

methanol:water(1:1),acetone,acetone:water(1:1)to

0.5 g of spiked sediment sample. Sediment samples

were extracted for 60min using a 100-µmPDMS

fiber.Fig6showstheresponseforallOCPsafteradd-

ing of different solvents. The highest responsewas

Figure 5.Effectofsampleweight,using100-µmPDMSfiber,extractiontemperature70oCand

extractiontime60min,additionofwater5mL

20 KKU Res. J. 2012; 17(1)

obtainedwhen5mLofwaterwasaddedtothespiked

sedimentwhiletheresponseofOCPswiththepresence

ofmethanol:water(1:1),acetone:water(1:1),methanol

andacetonewerenotobserved.Theenhancedsensitivity

obtainedwhen addingwater to sediment could be

duetothedisplacementofanalytesfromtheactivesites

inthesedimentsandtothelowsolubilityofthetarget

analyteinwater(2).Therefore,theadditionofwater

wasselectedtothefurtherexperiments.

3.6 Effect of liquid volume

The partitioning of semi-volatiles

organiccompoundsbetweenthesoilandtheheadspaceis

generallylow,andtheadditionofwatercanenhancethe

releaseofvolatileorganiccompounds(VOCs)fromthe

soilmatrix(11).ToincreasethereleaseofOCPsfrom

sediment,differentvolumesofwaterrangingfrom1to

10mLwereaddedinto0.5gofsediment.Fig7illus-

tratestheeffectofwater/sedimentratioontheextraction

efficiencyofOCPsusingtheHS-SPMEprocedureat

70oCfor60min.TheresponseofOCPsincreasedwith

thedecreasingwater/sedimentratio.Ahighestresponse

wasobtainedwhen1mLofwaterwasaddedto0.5g

sediment,theadditionofhigheramountofwaterwould

dilutetheconcentrationoftheOCPsandincreasethe

diffusionbarrierof theOCPsfromaqueousphaseto

gaseousphase(11).Therefore,amountof1-mLwater

wasselectedforthefurtherexperiments.

3.7 Effect of the addition of hydrophilic

solvent and salt

Theeffectoftheadditionofhydrophilic

solvent (methanol and acetonitrile) and salt to the

sampleswasstudied.Fig8showsthehigherresponse

observedinheptachlor,aldrin,endosulfanI,4,4-DDEand

endosulfanIIwhenaddingthehydrophilicsolvent(1%

v/v)buttheresponseofendrin,2,4-DDTand4,4-DDT

slightly decreased.The poor responsewas observed

whenaddingNaClsolution(1%w/v).Thisstudyshowed

thatnoincreaseintheresponsewasobservedafterthe

additionofsalt.SincetheOCPsanalytesareverylow

polarity(15).Incontrastwithotherreports,theaddition

ofsalttoaqueoussampleisfrequentlyusedtoenhance

the sensitivity ofHS analysis of polar compounds;

fornon-polarcompoundthiseffect isexpectedtobe

insignificant(14,15).Thefinalproposedmethodforthe

simultaneousextractionoftheOCPswas:HS-SPME

of0.5gsedimentsample(0%hydrophilicsolventand

Figure 6.Effectoftheadditionofthedifferentsolventtothesedimentmatrix(0.5g),using100-µmPDMS

fiber,extractiontemperature70oCandextractiontime60min

21KKU Res. J. 2012; 17(1)

NaCl)withadditionof1mLofwater,using100-µm

PDMSfiberat70oCfor60minwithstirring.

3.8 Analytical Performance

TherepeatabilityofHS-SPMEprocedure

wasobtainedbyanalyzingfivereplicatespikedsediment

samplesconsecutivelyattwoconcentrationlevels(0.01

ng/gand0.1ng/g).The%RSDobtainedwasbetween

1.41and7.98%,andtheprecisionofthismethodwas

good.Thelimitofdetection(LOD)wasevaluatedby

comparingthesignaltonoiseratio(S/N)ofthelowest

concentrationtoaS/N=3.Theresultsshowedthatthe

methodalloweddetectionofOCPsinsedimentsamples

atconcentrationlowerthan0.01ng/g.

Seriesofsixconcentrationlevelswereobtained

byspikingsedimentsamplewithalltheorganochlorine

pesticidesinaconcentrationrangingfrom0.004to0.4

Figure 7.Effectofliquidvolume,using100-µmPDMSfiber,extractiontemperature70oC

andextractiontime60min,additionofwaterintosedimentsample0.5g

Figure 8. Effectoftheadditionofhydrophilicsolventandsalt,using100-µmPDMSfiber,extraction

temperature70oCandextractiontime60min,additionofwaterintosedimentsample0.5g

22 KKU Res. J. 2012; 17(1)

ng/g,dryweight.Eachsolutionwasanalyzedinfive

replicates.Thelinearityofthemethodhasbeeninves-

tigatedovertherangeof0.004-0.4ng/gandtheeight

OCPs had correlation coefficients of the calibration

graphs greater than 0.995. Themean recoveries

obtainedfortheeightorganochlorinepesticidesspiked

insedimentsamples.Therecoverywasdeterminedas

thepeakareaofrealsamplespikedwithanalyteattwo

concentrationlevels.Therecoveriesofallanalyteranged

between80and99%.ThisdemonstratesthatHS-SPME

with polydimethylsiloxane is a simple, fast, solvent

free, inexpensive,preciseandaccurate technique for

quantitativedeterminationoftheOCPsinriversediment

sampleswhencomparedtotheconventionalmethod.

Theconventionalmethodsuchassoxhletextraction,

ultrasonic solvent extraction and accelerate solvent

extractionthatanalyticalproceduresusuallycomprised

of extraction,clean-upandanalysiswithdrawbacks

including time, solvent consumption, expensive

and both labor-and time-consuming because typical

sedimentsamplescannotbedirectlyanalyzedbythe

chromatographictechniques(3,14).WiththeHS-SPME

technique,thelimitationsoftheconventionaltechnique

canberemoved.OptimizationoftheHS-SPMEparameter

affectingthemethodsensitivityshouldbedevelopedin

ordertoenableincreaseintheamountofmostOCPs

andtoimprovethelimitofdetection.Thecombination

ofHS-SPMEwithGC-ECDcanbeachievedverylow

limits of detection (0.002-0.004 ng/g-dryweight),

as the total amount of extracted analytes is used for

thedetermination.Thus theHS-SPME-GC-ECDcan

beconsideredasanalternative for thedetermination

oftheOCPsinsedimentsamplesandcanbeverified

withoutdifficulty.

3.9 Application to real sediment samples

The sediment samples from Moon

riverweredeterminedtheOCPsusingthedeveloped

HS-SPME technique.These sampleswere collected

fromsixstations,duringNovember2010toSeptember

2011. The contamination of heptachlor, aldrin,

endosulfanI,endosulfanII,4,4-DDE,endrin,2,4-DDT

and4,4-DDTwereintherangeof0.0022to0.5212

ng/g, 0.0060 to 0.0097ng/g, 0.0025 to 0.0079ng/g,

0.0063to0.0090ng/g,0.0027to0.0214ng/g,0.0040

to0.0054ng/g,0.0045to0.0079ng/g,0.0040to0.0066

ng/g,respectively.ThequantitiesoftheOCPsfoundin

sedimentsampleswerenotoverthesoilandsediment

qualitystandardbythePollutionControlDepartment.

4. Conclusion

Headspace solid-phase microextraction

technique is a fast, inexpensive and solvent free

techniquethathasbeenprovedaccurateintheanalysis

of organochlorine pesticides in sediment and soil.

HS-SPME-GC-ECDprocedure has been optimized

usinga100-µmPDMSfiberforextractionoftheOCPs

inrealsamples.HS-SPMEextractionwasfinallycarried

outusingtheextractiontimeof60minattheextraction

temperature70oC,maintainingastirringoftheslurry,

thendesorptionintheGCinjectorwaskeptat270oC

for 5min.The optimizedHS-SPMEprocedure has

beenshowntobereliableforfast,accurateandprecise

monitoringofOCPsintheriversedimentsamples.

5. Acknowledgement

We are grateful to theChemistry program,

FacultyofScience,UbonRatchathaniRajabhatUniversity

andDepartmentofChemistry,FacultyofScience,Ubon

RatchathaniUniversityforfinancialsupportandproviding

uswiththefacilitiesforOCPanalyses.

23KKU Res. J. 2012; 17(1)

6. References

(1)ChangS,DoongR.Concentrationandfateof

persistentorganochlorinepesticidesinestuarine

sediments using headspace solid-phase

microextraction. Chemosphere. 2006;62:

1869-1878.

(2) AlvarezMF,LloblmpartM,LamasJP,Lores

M,Jares CG,CelaR,etal. Simultaneous

determination of traces of pyrethroids,

organochlorinesandothermainplantprotection

agents in agricultural soils by headspace

solidphasemicroextraction-gaschromatography.

Journal ofChromatographyA. 2008;1188:

154-163.

(3) Magdic S, Pawliszyn J. Analysis of

organochlorinepesticidesusingsolid–phase

Microextraction.JournalofChromatography

A.1996;723:111-122.

(4) Fatoki OS, Awofolu RO.Methods for

selective determination of persistent

organochlorinepesticideresiduesinwaterand

sedimentsbycapillarygaschromatography

and electron-capture detection. Journal of

ChromatographyA.2003;983:225-236.

(5) CastroJ,BruneteCS,TadeoJL.Multiresidue

analysis of insecticides in soil by gas

chromatography with electron-capture

detect ion and conf i rmat ion by gas

chromatography-massspectrometry.Journalof

ChromatographyA.2001;918:371-380.

(6) Vagi MC,PetsasAS,Kostopoulou MN,

KarananoliMK,LekkasTD.Determination

of organolchlorine pesticides in marine

sediments samples usingultrasonic solvent

extractionfollowedbyGC/ECD.Desalination.

2007;210:146-156.

(7 Yehouenou E, Pazou A, Boko M,

CornelisAMG,AhissouH,LaleyeP,etal.

Organochlorine and organophosphorus

pesticide residues in the Oueme River

catchment in the Republic of Benin.

EnvironmentInternational.2006;32:616-623.

(8) Keithmaleestti S, Varanusupakul P,

SiriwongW, ThirakhuptK, Robson M,

KitanaN.ContaminationofOrganchlorine

PesticidesinNestsoil,Egg,andBloodofthe

S n a i l - e a t i n g T u r t l e (Ma l a y emy s

macrocephala) from the chao Phraya

RiverBasin,Thailand.WorldAcademyof

Science, Engineering and Technology.

2009;52:444-449.Thai.

(9) LambropoulouDA,AlanisTA.Optimization

of headspace solid phasemicroextraction

conditions for the determination of

organophosphorus insecticides in natural

waters. Journal of Chromatography A.

2001;922:243-255.

(10)Wurl O, Obbard JP. Organochlorine

pesticides,polychlorinated biphenyls and

polybrominateddiphenylethersinSingapore’s

coastalmarine sediments. Chemosphere.

2005;58:925-933.

(11)Doong R, Liao PL. Determination of

organochlorinepesticidesandtheirmetabolites

insoilsamplesUsingheadspacesolid-phase

microextraction.JournalofChromatography

A.2001;918:177-188.

(12)WongklomA,IntaraprasertJ.Determination

of organochlorine pesticides residues in

sedimentfromShiriverandMoonriverbygas

chromatography.JournalofSrinakharinwirot

University.2011;3suppl1:20-26.Thai.

24 KKU Res. J. 2012; 17(1)

(13)WongklomA,IntaraprasertJ.Contamination

oforganochlorinepesticidesinsedimentfrom

ShiandMoonriver,Thailand.LoasJournal

onAppliedScience.2011;2(1):822-827.

(14) Santos FJ, SarrionMN,Galceran MT.

Analysisofchlorobenzenesinsoilsbyhead-

space solid-phasemicroextraction and gas

chromatography-iontrapmassspectrometry.

Journal of ChromatographyA. 1997;771:

181-189.

(15)Llompart M,Li K,FingasM.Headspace

solid-phasemicroextraction(HS-SPME)for

the determination of volatile pollutants in

soils.Talanta.1999;48:451-459.