Chemistry Reference
In-Depth Information
curvesinthetestedconcentrationrangeupto2.5mMandarelinearforallcomponentsofinter-
est:ACS-K,saccharin,ASP,cyclamate,sorbitol,mannitol,lactitol,andxylitol.Theconcentration
detectionlimitsforthedeterminedcompoundsrangebetween0.024and0.081mM.Goodpreci-
sionofthemethodisevidencedbyfavorableRSDvaluesforallcompoundsrangingfrom0.8%to
2.8%obtainedattheanalyteconcentrationof1.0mM(
n
=6).Theanalysistimeisabout20min.
Simplicity,accuracy,andlowcostofanalysesmakethisanalternativeproceduretomethodsused
sofarforthedeterminationofionizablesweeteners(Herrmannováetal.2006).
TLCmethodshavebeendevelopedforanalysisofsweeteners.ASP,ACS-K,sodiumcyclamine,
and benzoic acid are separated on thin layers of silica gel G with 10% (v/v) ethanol-40% (v/v)
isopropanol-1%(v/v)(12.5%)aqueousammonia.Thischromatographicsystemwasappliedtothe
analysisofsweetenersin23sparklingandnonsparklingdrinks(Baranowskaetal.2004).
Anewchromatographicmodalitythatdoesnotrequirehighpressuresandalsoallowsrenewal
ofthestationaryphaseasdesiredisreported.Thetechniqueisbasedonathin-layerparamagnetic
stationaryphase(Fe
3
O
4
-SiO
2
)retainedontheinnerwallofaminicolumnthroughtheactionofan
externalmagneticield,whichalsoplaysanimportantroleinseparatingtheanalytes.Accordingly,
the name “renewable stationary phase liquid magnetochromatography” has been proposed for it.
ThetechniqueisusedtoseparateandquantifythesugarsubstituteASPanditsconstituentamino
acids(hydrolysisproducts),l-asparticacidandl-phenylalanine,indietizzysoftdrinks.Whenthe
resultsobtainedforASPwerecomparedwiththoseobtainedusingtheHPLCreferencemethodof
LawrenceandCharbonneau,nosigniicantdifferenceswereobserved.Thesystemproposedisfully
automated,makingitaneconomicandcompetitivealternativetoconventionalmethodsofdeter-
miningASPanditsaminoacidcomponents(Barradoetal.2006).
ThedeterminationofASPandACS-Kintabletopsamplesaswaspreviouslydescribedhasbeen
achievedbyFouriertransformmiddle-infrared(FTIR)spectrometry.Withtheuseofafullymecha-
nizedonlineextraction,thecontactoftheoperatorwithtoxicsolventswasavoidedanddifferenti-
atesbetweensamplesthatcontainASPandACS-KandthosethatincludeonlyASP,reducingthe
timeneededfortheanalysisofthelastkindofsamplesto5min.Themethodinvolvestheextraction
ofbothactiveprinciplesbysonicationofsampleswith25:75v/vCHCl
3
/CH
3
OHanddirectmeasure-
mentofthepeakheightvaluesat1751cm
−1
,correctedusingabaselinedeinedat1850cm
−1
forASP,
andmeasurementofthepeakheightat1170cm
−1
intheirst-orderderivativespectra,correctedby
usingahorizontalbaselineestablishedat1850cm
−1
forACS-K.Limitofdetectionvaluesof0.10%
and0.9%w/wandRSDsof0.17%and0.5%arefoundforASPandACS-K,respectivelyOnthe
otherhand,anHPLCmethodneedsapproximately35minforcompletion(Armentaetal.2004a,b).
Electrochemistry at the liquid−liquid interface enables the detection of non-redox-active spe-
cieswithelectroanalyticaltechniques,andtheelectrochemicalbehavioroftwofoodadditives,ASP
andACS-K,canbeinvestigated.Bothionswerefoundtoundergoion-transfervoltammetryatthe
liquid−liquidinterface.Liquid−liquidelectrochemistryasananalyticalapproachinfoodanalysis
isverysuitable.Differentialpulsevoltammetrywasusedforthepreparationofcalibrationcurves
overtheconcentrationrangeof30−350μMwithadetectionlimitof30μM.Thestandardaddition
methodwasappliedtothedeterminationoftheirconcentrationsinfoodandbeveragesamplessuch
assweetenersandsugar-freebeverages.SelectiveelectrochemicallymodulatedLLEofthesespe-
ciesinbothlaboratorysolutionsandinbeveragesampleswasachieved(Herzogetal.2008).
4.17 CONCLUSIONS
The determination of artiicial sweeteners individually or simultaneously in mixtures is very
important for legal aspects. Researchers focus their efforts on developing analytical methods for
simple, rapid, and low-cost sensitive determination. Sensitive and robust analytical methods are
essentialtomeettheneedsofgrowingmarketsinqualitycontrolandconsumersafety.Scientists
Search WWH ::
Custom Search