Chemistry Reference
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background electrolyte. A complete separation of the analytes could be attained in less than 6
min.Thelimitsofdetection(LOD)andlimitsofquantiication(LOQ)wereconsideredbetterthan
thoseusuallyobtainedbyCEwithphotometricdetection.Recoveriesrangingfrom94%to108%
wereobtainedforsamplesspikedwithstandardsolutionsofthesweeteners.Therelativestandard
deviation(RSD)fortheanalysisofthesampleswiththeCE-C
4
Dmethodvariedintherangeof
1.5%-6.5%.
SeparationandquantiicationofsweetenersusingCEhavebeendescribedbyotherauthorsasa
rapidandsimplemethod(Frazieretal.2000;Horieetal.2007;PesekandMatyska1997;Schnierle,
Kappes,andHauser1998;Thompson,Trenerry,andKemmery1995).
Frazieretal.(2000)employedtheMEKCmodewitha20-mMcarbonatebufferatpH9.5asthe
aqueousphaseand62mMsodiumdodecylsulfateasthemicellarphase.
Arapidmethodforthedeterminationofartiicialsweetenersinlow-joulesoftdrinksandother
foodsbyMEKCisdescribedbyThompson,Trenerry,andKemmery(1995b).Theartiicialsweet-
enersaspartame,saccharin,acesulfameK,alitame,anddulcinandtheotherfoodadditivesarewell
separatedinlessthan12minusinganuncoatedfused-silicacapillarycolumnwithabuffercon-
sistingof0.05-Msodiumdeoxycholate,0.01-Mpotassiumdihydrogenorthophosphate,and0.01-M
sodium borate operating at 20 kV. Dehydroacetic acid was used as the internal standard for the
determinations.Thelevelsofartiicialsweetenerswereingoodagreementwiththosedetermined
by the HPLC procedure. The MEKC (Thompson et al. 1995a) procedure has the same order of
repeatabilityandisfasterandlesscostlytooperatethantheHPLCmethod.
PhotometricdetectionintheUVregionisthemostcommonlyuseddetectionmethod,although
forsomeapplications,itshowsinadequatelimitsofdetectionbecauseofthelowUVabsorptivi-
tiesofmostsweeteners,especiallycyclamate(Bergamo,deSilva,anddeJesus2011).Conductivity
detectionisagoodalternativemethodforcompoundslackingastrongUV-absorbingmoiety.Using
thisdetectiontechnique,anisotachophoresismethodwaspublishedbyHerrmannovaetal.(2006)
forthedeterminationofsweetenersinchewinggumsandcandies.
High-performanceCEhasbeenemployedbyPesekandMatyska(1997)toanalyzetheaspar-
tameinfoodproductsusingabarecapillary,apH2.14buffer,anddetectionat211nm.Theanalysis
timewasfasterthanthatreportedforHPLCmethods.
Themobilephasecanbemethanol-water,methanol-aceticacid,methanol-phosphatebuffer,
methanol-ammoniumcitrate,oracetonitrile-phosphatebufferwhenreversed-phasecolumns(RP-
C18)areused.Methanol-phosphoricacidandNa
2
CO
3
orNaOHsolutionswereusedwithamino
andion-exchangecolumns,respectively.AcesulfameK,alitame,aspartame,glycyrrhizin,neohes-
peridindihydrochalcone(NHDC),saccharin,andsteviosidecanbedeterminedbyUVabsorbance
(192-282nm)andbyamperometricorconductometricdetectioninthecaseofion-chromatographic
procedures(Yebra-Biurrun,2005).
9.18.2 Ion Chromatography
Chromatographicmethods(Wasik,McCourt,andBuchgraber2007;YangandChen2009;Zhu
etal.2005)havebeenemployedtodetectartiicialsweetenersinfood.
Anovelionchromatographicmethodwasproposedforthesimultaneousdeterminationofarti-
icial sweeteners (sodium saccharin, aspartame, and acesulfame K) by Chen and Wang (2001).
Separationwasperformedonananion-exchangeanalyticalcolumnoperatedat408°Cwithin45
minbyanisocraticelutionwith5-mMaqueousNaH
2
PO
4
(pH8.20)solutioncontaining4%(v/v)
acetonitrileaseluentandthedeterminationbywavelength-switchingUVabsorbancedetection.The
detectionlimits(signal-to-noiseratioof3:1)forallanalyteswerebelowthesub-milligrampermil-
lilietlevel.Theresultsalsoindicatedionchromatographypossiblywouldbeabeneicialalternative
toconventionalHPLCfortheseparationanddeterminationofthesecompounds.
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