Low Calorie Nonnutritive Sweeteners - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 102

ASPcanbedeterminedbyHPLCwithelectrochemicaldetection.ASP,whichiselectrochemi-
callyinactive,ismadeoxidizableintherange0.1-1.1Vafterpostcolumnirradiationat254nm.A
detectionlimitof0.5mg/L(signal-to-noiseratio3:1)isattainedusingacoulometricdetectorwith
theworkingcellsetat0.8VandaC 6 column(150×4.6mmI.D.)operatedunderisocraticcondi-
tionswith0.1%perchloricacid-methanol(85:15,v/v)astheeluentatalowrateof1mL/min.A
linearresponseforaqueoussolutionsofASPintherange1to20mg/Landa5%standarddeviation
forivereplicateinjectionswereobtained.ThemethodwasappliedtothedeterminationofASPin
twodietcolas(GallettiandBocchini1996).
The separation and determination of the sweetener ASP by IC coupled with electrochemical
amperometricdetectionarereported.TypicallyinIC,electrochemicaldetectionisemployedsuch
asanamperometricorconductivitydetector.Ontheotherhand,UVabsorbingexcipientssuchas
lavors and dyes may not give any electrochemical response and can therefore be eliminated as
aninterferentinquantitationoftheanalyte.Thus,ICofferstheopportunitytostreamlinemethod
developmentandincreasesamplethroughput.Sodiumsaccharin,ACS-K,andASPwereseparated
using 27.5 mM NaOH isocratic elution on a Dionex IonPac AS4A-SC separation column. ASP
canbedeterminedbyintegratedamperometricdetectionwithoutinterferencefromtheothertwo
sweeteners. The method can be applied to the determination of ASP in tabletop, fruit juice, and
carbonatedbeveragesamples,andtheresultsobtainedbyintegratedamperometryareinagreement
withthoseobtainedusingaUVdetectionmethod.Therecoveriesforsamplesrangedfrom77.4%to
94.5%.ThepeakarearesponseforASPislinearintherange0.1-10μg/mL.Forsevenconsecutive
injectionsofastandardsolutionwithaconcentrationof5μg/mL,theRSDis1.29%,andthedetec-
tionlimit(signal-to-noiseratioof3:1)is0.031μg/mLforASP(Quetal.1999).
4.15.4 Determination of Cyclamate
ThecommonHPLC-UVdetectionmodeisnotsuitablefordeterminationofcyclamatebecause
ofthelackofUVchromophoreinitsmolecule.Somecomplicatedandtime-consumingprocedures
are necessary for the absorbance detection of this sweetener in HPLC. This problem has been
solvedbyusingindirectUVphotometry,postcolumnion-pairextraction,andprecolumnderivatiza-
tion.Oneoftheirstapproachesemployedpostcolumnion-pairextractionwithabsorbancedetec-
tion for the LC determination of cyclamate. After chromatographic analysis, the sweetener was
mixedwithanappropriatedye(methylvioletorcrystalviolet)anddetectedbyabsorptioninthe
visible(Vis)range.Inthismethod,theelutedsweetenerismixedwithanappropriatedye(methyl
violetorcrystalviolet)beingdetectedbyabsorptionintheVisrange(Lawrence1987).
Hydrolysisofcyclamatetocyclohexylaminehasbeenemployedfortheanalysisoftabletop
sweeteners.Thehydrolysisstepwasperformedbatchwisebytreatingcyclamatewithhydrogen
peroxideandhydrochloricacid.Thecyclohexylaminewasderivatizedwith1,2-naphthoquione-
4-sulfonate (NQS) in an low injection system. The NQS derivative was monitored at 480 nm
(Caberoetal.1999).
CyclamatewasdeterminedinsoftdrinksusingRP-HPLCcombinedwithindirectVisphotom-
etryat433nm.Theanalyticalsignalwasderivedfromchangesinabsorbanceofmobilephasewith
additionofchromogenicdye(MethylRed;Choietal.2000).
Cyclamatesintabletopsweetenersandsomelow-caloriesoftdrinksweredeterminedbyanFIA
spectrophotometricmethod.Theprocedureutilizedthereactionbetweennitriteandcyclamatein
mediumcontainingphosphoricacid.Theexcessofnitritewasdeterminedbythemeasurementof
absorbanceofGriessreactionproductat535nm(Gouveiaetal.1995).
An HPLC-ESI-MS method using tris(hydroxymethyl) aminomethane as an ion-pair-forming
agentwasemployedforanalysisofcyclamateinfoods.CyclamatewasseparatedonaC8columnin
isocraticmodewith100%aqueousmobilephase.MSwasoperatedinnegative,selectedion( m/z =178)
recordingmode.Themethodwasfoundtobehighlysensitive,speciic,andsimple(Huangetal.2006).