依實驗室自行架設的靜電紡絲設備，並且利用同軸紡頭穩定紡出 高度順向薄膜纖維。以目前測試吸附丙酮氣體的測試結果而言，聚乳 酸薄膜纖維的吸附效果最佳，一毫克聚乳酸薄膜纖維可吸附約 150 微克的丙酮蒸氣。
應用至表面稱強拉曼光譜方面，使用不同奈米銀的還原合成方法，
以鹽酸羥胺還原法的效果最佳，在真實樣品中的偵測極限可達 100 ppb。另外，相較於奈米銀溶液可能因產生聚集而沉澱，紡入微孔陣 列薄膜的奈米銀粒子則以固體顆粒的形式存在，可存放時間較長。
81
學會發表
參與會議：第十九屆分析技術交流研討會 時間：中華民國 100 年 5 月 25 日 地點：國立臺灣師範大學 公館校區 題目
Development and application of functional microtube array membranes by the co-axial electrospinning technique.
Huan an, Lee(李桓安), Chien-Chung Chen and Cheng-Huang, Lin
82
論文發表
A microwave-assisted fluorescent labeling method for the separation and detection of amphetamine-like designer drugs by capillary electrophoresis Kuan-Fu Chen, Hsun Lee, Ju-Tsung Liu, Huan-An Lee and
Cheng-Huang Lin*
FORENSIC.SCI.INT. 228 (2013) 95-99
83
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A microwave-assisted fluorescent labeling method for the separation and detection of amphetamine-like designer drugs by capillary
electrophoresis
Kuan-FuChen, HsunLee, Ju-TsungLiu, Huan-An Lee,Cheng-HuangLin*
DepartmentofChemistry,NationalTaiwanNormalUniversity,88Sec.4,TingchowRoad,Taipei,Taiwan
1. Introduction
CE–LIF(capillaryelectrophoresis–laserinducedfluorescence)is oneofthemostpopularandpowerfultechniquesavailableforthe analysisof biological samplesand illicit drugs [1–5]. When an argonion laser (488nm) isused as theexcitation source, FITC (fluoresceinisothiocyanateisomerI)isanearlyperfectfluorescent labelingreagent.Insteadofanexpensiveargonionlaser,theuseof ablueLED[6–9]orbluediodelaserhasrecentlybecomepopular [10,11]. FITC is yellow-orange in color with an absorption maximum at 495nm and, upon excitation, it emits a yellow-greencolorwithanemissionmaximumat525nm.However,the overalllabelingprocessintimeconsuming,whenFITCisusedas thefluorescentlabelingreagent.Forthisreason,whileCE–LIFisa highly sensitive technique, it is not routinely used as a complementarymethodforrapidscreening.
Theincreasingavailabilityofamphetamine-likedesignerdrugs ontheillicitmarkethasbecomeaserioussocialproblem[12–15].
However,even thoughdrugabuseis aseriousproblem [16,17],
little information is available concerning methods for the extractionanddetectionofthesetypesofcompounds.Fromthe point of view of screening and confirming the numbers of clandestine tablets that are probably available on the illicit market,amorerapidscreeningmethodwouldbehighlydesirable.
Asofthiswriting,GC–MS(gaschromatograph–mass spectrome-try)[18–21]andLC–MS(liquidchromatograph–mass spectrome-try) [22–25] continue to be the officially prescribed methods.
However,whiledataobtainedbymassspectrometryconstitutes legally acceptable evidence, secondary evidence acquired by meansofadifferenttechniquewouldbehighlydesirable.
In Taiwan in2011, p-chloro-amphetaminewaspermanently placedinScheduleIIIand,becauseofthis,methodsforitsanalysis, aswellasderivativesthereof,areneeded.Inthisstudy,weselected o-, m-, p-chloro- and o-, m-, p-fluoro-amphetamines as model compounds.Amicrowaveovenwasusedtoincreasetherateofthe fluorescent labeling reaction. Results obtained by classical methods,includingCE–UVandLC–MSarealsoreportedandthe results are compared to data acquired using this method. The analysisofthesixdesignerdrugsinahumanoralfluidsamplewas optimized,thedetectionlimitsandprecisionofthesemethodsare discussed and completedata regarding their characteristicsare reportedherein.
ARTICLE INFO
Articlehistory:
Received18May2012
Receivedinrevisedform22February2013 Accepted26February2013
Availableonline22March2013
Keywords:
Amicrowave-assistedfluorescencelabelingmethodforuseinCE–LIF(capillaryelectrophoresis–laser inducedfluorescence)isdescribed.Sixamphetamine-likedesignerdrugs,namely,o-,m-,p-chloro-and o-, m-,p-fluoro-amphetamine derivatives, weresynthesized and used asmodel compounds. FITC (fluoresceinisothiocyanateisomerI)andablue-laserwereusedasthefluorescentlabelingreagentand excitationsource,respectively.Whenamicrowaveovenwasused,thereactionwascompletewithin
5min,whiletheclassicalmethodrequiredatleast20h(usually,anovernightreaction).Amimicoral fluidsamplewasobtainedbyspikingoralfluidfromavolunteerwiththesixstandards,andafterliquid–
liquidextractionandmicrowave-derivatization,itwaspossibletoprocesstheanalytesbyCE–LIFwithin aperiodof10min;thewavelengthoftheblue-laserusedwas473nm.Forcomparison,dataobtained usingclassicalmethods,includingCZE–UV(capillaryzoneelectrophoresis–UVabsorbancedetection), sweeping-MEKC–UV(micellar electrokineticchromatography–UVabsorbancedetection)and LC–Q-TOFMS(liquidchromatography/electrosprayionizationquadrupoletime-of-flightmassspectrometry) arealsoreported.
ß2013ElsevierIrelandLtd.Allrightsreserved.
*Correspondingauthor.Tel.:+886277346170;fax:+886229324249.
E-mailaddresses:chenglin@cc.ntnu.edu.tw,chenglin@ntnu.edu.tw(C.-H.Lin).
ContentslistsavailableatSciVerseScienceDirect
Forensic Science International
j o urn a lhom e pa g e :ww w . e l se v i e r. c om / l oca t e / f ors ci i nt
0379-0738/$–seefrontmatterß2013ElsevierIrelandLtd.Allrightsreserved.
http://dx.doi.org/10.1016/j.forsciint.2013.02.045
o-,m-,p-Chloro-ando-,m-,p-fluoro-amphetaminesweregenerouslydonatedby theMilitaryPoliceCommand, ForensicScience Center, Taiwan.Followingthe synthesis,thefinalproductswereverifiedbyAnnandAlexanderShulginintheir bookentitledTiHKAL(PhenethylaminesIHaveKnownandLoved)[26].Following thesynthesis-steps,thefinalproductswereverifiedbyNMR,IRandGC/MS.All otherchemicalswereofanalyticalgradeandwereobtainedfromcommercial sources.
2.2.Apparatus
In-housefabricatedCE–UVandCE–LIFsystemswereusedthisstudy.TheCE set-upswereidenticaltothoseusedinourpreviousstudiesandareabbreviatedherein [8,27–29].Thebluelaserused(100mW/473nm)waspurchasedfromSinhuang TechnologyCo.,Ltd.,Taiwan;amicrowaveoven(SAMPO,RE-081M1)wasobtained fromalocalshop.TheLC–Q-TOFMSsystemconsistedofaWaters1525binaryHPLC pump,areversedphasecolumn(Cosmosil5C18-MS,5mm,25cm4.6mmi.d.;
NacalaiTesque,Kyoto,Japan)andamassspectrometer(MicromassQ-TOF).
2.3.Oralfluidextractionprocedure
Extractionprocedureswerereferencedandmodifiedfromtheliterature[30–32].
Inatypicalexperiment,a500-mLaliquotofanoralfluidsampleobtainedfroma humanvolunteerwasplacedinatesttubeandthesolutionspikedwiththe6 amphetaminederivatives(0.5mgeach).ThepHvaluesofthespikedoralfluid sampleswereadjustedto9.0byaddingammoniumcarbonate(250mLof0.2M).
Followingthis,1.3mLofanethylacetate–hexanesolution(4/1,v/v)wereadded, followedbygentlemixingfor1minandcentrifugationfor5min.Theupperlayer wasthencollectedandevaporatedtodryness.Theresiduewasdissolvedin500mL ofmethanolandfilteredthrougha0.45mmnylonfilterforuseinthesubsequent experiments.
2.4.Fluorescencederivatization
To150mLofasolutioncontaining50mLof10mMsodiumtetraborate,100mLof asolutionofanamphetamine-likedesignerdrug(20mg/mLeachinH2Oororal fluid)wasadded.Thereactionwasinitiatedbytheadditionof50mLofaFITC solution(500mg/mLin acetone)to giveconcentrations of[amphetamine-like designerdrugs]equalto10mg/mLand[FITC]equalto125mg/mL,respectively.The reactionsolutionwasallowedtostandatroomtemperatureinthedarkfor24hor
2.5.SeparationconditionsfortheCZE/UV
TheUVabsorptionmaximaforthechloro-andfluoro-amphetaminesareat266 and 262nm; after fluorescent labeling the observed fluorescence emission maximumwasintherangeof543–548nm.Thisindicatesthatthesecompounds canbedetectedandidentifiedusingeitherCEorHPLCseparation,basedontheir fluorescenceproperties.
3. Resultsanddiscussion
Fig.1showstypicalelectropherogramsfortheseanalytesfor variousseparationmodes(frameA,CZE/UV;frameB, sweeping-MEKC/UV modes, respectively). The concentrations of the six samplesare100mg/mLinframeA.Theoptimalbufferfortheir separation consisted of 7.5mM b-CD, phosphate (NaH2PO4, 50mM/Na2HPO4, 100mM) in a mixture of acetonitrile–metha-nol–water(12.5:17.5:70,v/v/v)pH3.1. Theappliedvoltageand current were +15kV and 64mA; total/effective length of the capillary usedwas 50/41cm. Theorder of migration ofthesix analytesbasicallyfollowedthemasspercharge.Ascanbeseen fromtheelectropherogram,theorderofmigrationis:o-fluoro-, m-fluoro-,p-fluoro-,followedbytheo-,m-,p-chloro-derivatives.The insetinFig.1Ashowstheresultswhennob-CDisused.Inthiscase, theseparationwasnotcompletebecauseofthesimilarityofthe chemicalstructuresofthesixanalytes.Numerousattemptswere madeto separateandidentifythem using LC–Q-TOFMS (liquid chromatography/electrospray ionization quadrupole time-of-flightmassspectrometry).Thefindingsshowthat,whenagradient elution(A,0.1%formicacidaqueoussolution/pH2.5;B,methanol) wasused,the sixanalytescan benearly completelyseparated, except for the m- and p-chloro-amphetamines, which were incompletelyseparated.Toachievecompleteseparationofthese 2 compounds, a chiral column would be needed. The order of
20
Fig.1.UVabsorptiondetection.Electropherogramsofamixtureofthesixamphetamine-likedesignerdrugsbyvariousseparationmodes(frameA,CZE–UV;frameB, sweeping-MEKCmode,respectively).CEconditions:A,asolutionofacetonitrile–methanol–water(12.5:17.5:70,v/v),containingphosphate(NaH2PO4,50mM/Na2HPO4, 100mM)and7.5mMb-CD(inset,non-b-CDsolution),pH3.1.Thevoltageusedwas+15kV(current,64mA);B,abackgroundelectrolyteconsistedofacetonitrile–
methanol–water(5:30:65,v/v),containing50mMNaH2PO4,75mMofSDS.Samplematrix,50mMNaH2PO4;sampleinjectedlength,14cm.Thevoltageusedwas 22kV (current, 40mA);total/effectivelengthofthecapillaryusedwas75/61cm,respectively.
determinedtobe0.5and1.0mg/mLforthestandardsolutionand theoralfluidextract,respectively.
Inthecaseofthechloro-andfluoro-amphetaminederivatives, intersystemcrossingoccursmoreefficientlybystabilizationofthe tripletstatebyintramolecularhydrogenbonding,andasaresult, the absorption and fluorescence intensities are weaker, which resultsin poor detection limits. For such a weakly fluorescent compound,anonlinesampleconcentrationtechniqueor fluores-cencederivatizationis recommended.Fig.1Bshowstheresults obtained when the sweeping-MEKC mode was used. The optimizedbackgroundelectrolyte consistedof 75mM SDS,and 50mM NaH2PO4 in a solution of acetonitrile–methanol–water (5:30:65, v/v) pH 2.13. The applied voltage and current were 22kV and 40mA; total/effective length of the capillary (50mm, i.d.) used was 75/61cm (sample injection length, 14cm). Under these conditions, the LOD can be improved to 0.5mg/mL.However,whenthesweeping-MEKCmethodwasused, theeffectsofsampleinjectionlengthandthecorrespondingsignal intensity need to be further investigated. Choosing between a longer sample injection length (higher sensitivity) and better separation efficiency (lower sensitivity) is an important, but difficultchoice.Furthermore,becauseofthenumerousunknown matrixeffectsassociatedwithanauthenticoralfluidsample,many unidentified peaks (due to all UV absorbers) appear when the sweeping-MEKCtechniquewasused.Incontrasttothis,whenthe CE–LIFmethodwasused,asimpleseparationbuffercanbeused andtheLODcanbedramaticallyimproved,evenwhenanonline sampleconcentrationtechniqueisnotused.Asshownintheinset inFig.2B,theLODsforthesixamphetamine-likedesignerdrugs can beimproved to 0.05mg/mL after fluorescentlabeling with FITC.Furthermore, FITConlyreacts withprimary(asin thesix analytes)andsecondaryamines.Thischaracteristiccanbeuseful intermsofavoidinginterferencebyextraneouscomponentsinthe saliva sample. However, as mentioned above, the classical fluorescent labeling method is time consuming in terms of completingthe reaction.In order toshorten thetime required
used to increase the rate of the fluorescence derivatization reaction.Fig.2showstypicalmicrowave-assistedCE–LIF electro-pherograms of an extract of humanoral fluids. The optimized separation buffer is simple, consisting of only a borate buffer (tetraborate,10mM)containing75mMSDS(pH9.5).Theapplied voltageandcurrentwere+17kVand24mA;total/effectivelength ofthecapillary(75mm,i.d.)usedwas62/52cm.Frame(A)shows theresultsobtainedforextractsofacleanoralfluidsample.Ascan beseen,althoughsomepeaks,duetounknownmatrixeffects,are present,theresultsaremuchsimplerthantheresultsobtainedby LC–Q-TOFMS(datanotshown).Frame(B)showstheresultsforan oral fluid sampleobtained by spikinga cleanoral fluid sample collected from a human volunteer with the six amphetamine designerdrugs(spikedconcentration:0.5mg/mL,each).Ascanbe seen,eventhoughsomebackgroundpeaksarestillpresent,allof thesixanalytescanclearlybeidentified.Thus,thisapproachcanbe appliedtotherapidandsensitivedetectionandidentificationof amphetamine derivatives and related designer drugs in saliva obtainedfromsuspects.
In order to determine the time required to complete the microwave-assisted fluorescence derivatization and the corre-spondingsignalintensity,severaldifferentreactiontimes(0–48h) wereexamined.AsshowninFig.3,whenamicrowaveovenwas used, the derivatization was complete within 5min. However, when the time in the oven was increased to 10min, the fluorescence intensity decreased. The dashed line shows the intensitychangesofFITC.Incontrasttothis,usingtheclassical procedure,morethan20hwereneededtoreachthemaximum fluorescenceintensity,althoughtheintensitywasalmosttwo-fold thatforthemicrowavemethod.Fig.4showsanotherexample (2C-seriesdrugs)obtainedusingthemicrowave-assistedfluorescence derivatization procedure. In a previous study, we reported on optimizingtheseparationandonlinesampleconcentrationofthe 2C-seriesofphenethylaminedesignerdrugswithCE-fluorescence detection.Inthatstudy,LED-inducedfluorescencedetectionwas examinedbyderivatizingthecompoundsbyreactingthemwith
Fig.2.Microwave-assistedfluorescencederivatizationmethod.Electropherogramsofamixtureofthesixamphetamine-likedesignerdrugsforvarioussamples:frameA, salviablanksample;frameB,spikedsample;insets,theresultobtainedbyLC–Q-TOF-MSmethodandtheelectropherogramofthesixstandards,respectively.CEconditions:
A,anaqueoussolutioncontaining10mMtetraborateand75mMofSDS,pH9.5.Thevoltageusedwas+17kV(current,24mA).
FITC and a blue-LED was used as the fluorescence excitation source. For comparison, we repeated these analyses using the microwave-assistedmethod.Similartotheamphetamines deri-vativesexaminedinthisstudy,thederivatizationwascomplete within5min,andthefluorescenceintensitywasbetterthanthe resultsobtainedbythepreviousmethod.Thus,weconcludethat themicrowave-assistedmethodisveryusefulandthatitdoesnot affectthepropertiesofFITCorthesamples.
In this study, we describe the development of a novel microwave-assistedCE–LIF method. Itissuitable for usein the rapidscreeningofdrugs,sinceithasahighdegreeofsensitivity and the operating procedure is simple and economical. This methodconstitutesasensitive,simple,andeconomically comple-mentarymethodforeitherrapidscreeningorofficiallyprescribed methods(suchasGC/MSorLC/MS)foruseinforensicandclinical analysis,aswellasinrelatedwork.
Acknowledgment
ThisworkwassupportedbyagrantfromtheNationalScience CouncilofTaiwanunderContractNo.100-2113-M-003-006-MY3.
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